| 1. |
- Ausmees, Nora, et al.
(författare)
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SmeA, a small membrane protein with multiple functions in Streptomyces sporulation including targeting of a SpoIIIE/FtsK-like protein to cell division septa
- 2007
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Ingår i: Molecular Microbiology. - : Wiley. - 0950-382X .- 1365-2958. ; 65:6, s. 1458-1473
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Tidskriftsartikel (refereegranskat)abstract
- Sporulation in aerial hyphae of Streptomyces coelicolor involves profound changes in regulation of fundamental morphogenetic and cell cycle processes to convert the filamentous and multinucleoid cells to small unigenomic spores. Here, a novel sporulation locus consisting of smeA (encoding a small putative membrane protein) and sffA (encoding a SpoIIIE/FtsK-family protein) is characterized. Deletion of smeA-sffA gave rise to pleiotropic effects on spore maturation, and influenced the segregation of chromosomes and placement of septa during sporulation. Both smeA and sffA were expressed specifically in apical cells of sporogenic aerial hyphae simultaneously with or slightly after Z-ring assembly. The presence of smeA-like genes in streptomycete chromosomes, plasmids and transposons, often paired with a gene for a SpoIIIE/FtsK- or Tra-like protein, indicates that SmeA and SffA functions might be related to DNA transfer. During spore development SffA accumulated specifically at sporulation septa where it colocalized with FtsK. However, sffA did not show redundancy with ftsK, and SffA function appeared distinct from the DNA translocase activity displayed by FtsK during closure of sporulation septa. The septal localization of SffA was dependent on SmeA, suggesting that SmeA may act as an assembly factor for SffA and possibly other proteins required during spore maturation.
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| 2. |
- Becher, Paul G., et al.
(författare)
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Developmentally regulated volatiles geosmin and 2-methylisoborneol attract a soil arthropod to Streptomyces bacteria promoting spore dispersal
- 2020
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Ingår i: Nature Microbiology. - : Springer Science and Business Media LLC. - 2058-5276.
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Tidskriftsartikel (refereegranskat)abstract
- Volatile compounds emitted by bacteria are often sensed by other organisms as odours, but their ecological roles are poorly understood1,2. Well-known examples are the soil-smelling terpenoids geosmin and 2-methylisoborneol (2-MIB)3,4, which humans and various animals sense at extremely low concentrations5,6. The conservation of geosmin biosynthesis genes among virtually all species of Streptomyces bacteria (and genes for the biosynthesis of 2-MIB in about 50%)7,8, suggests that the volatiles provide a selective advantage for these soil microbes. We show, in the present study, that these volatiles mediate interactions of apparent mutual benefit between streptomycetes and springtails (Collembola). In field experiments, springtails were attracted to odours emitted by Streptomyces colonies. Geosmin and 2-MIB in these odours induce electrophysiological responses in the antennae of the model springtail Folsomia candida, which is also attracted to both compounds. Moreover, the genes for geosmin and 2-MIB synthases are under the direct control of sporulation-specific transcription factors, constraining emission of the odorants to sporulating colonies. F. candida feeds on the Streptomyces colonies and disseminates spores both via faecal pellets and through adherence to its hydrophobic cuticle. The results indicate that geosmin and 2-MIB production is an integral part of the sporulation process, completing the Streptomyces life cycle by facilitating dispersal of spores by soil arthropods.
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| 3. |
- Bush, Matthew J, et al.
(författare)
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c-di-GMP signalling and the regulation of developmental transitions in streptomycetes.
- 2015
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Ingår i: Nature Reviews. Microbiology. - : Springer Science and Business Media LLC. - 1740-1534 .- 1740-1526. ; 13:12, s. 749-760
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Forskningsöversikt (refereegranskat)abstract
- The complex life cycle of streptomycetes involves two distinct filamentous cell forms: the growing (or vegetative) hyphae and the reproductive (or aerial) hyphae, which differentiate into long chains of spores. Until recently, little was known about the signalling pathways that regulate the developmental transitions leading to sporulation. In this Review, we discuss important new insights into these pathways that have led to the emergence of a coherent regulatory network, focusing on the erection of aerial hyphae and the synchronous cell division event that produces dozens of unigenomic spores. In particular, we highlight the role of cyclic di-GMP (c-di-GMP) in controlling the initiation of development, and the role of the master regulator BldD in mediating c-di-GMP signalling.
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| 4. |
- Cantlay, Stuart, et al.
(författare)
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Influence of core divisome proteins on cell division in Streptomyces venezuelae ATCC 10712
- 2021
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Ingår i: Microbiology (Reading, England). - : Microbiology Society. - 1465-2080 .- 1350-0872. ; 167:2
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Tidskriftsartikel (refereegranskat)abstract
- The sporulating, filamentous soil bacterium Streptomyces venezuelae ATCC 10712 differentiates under submerged and surface growth conditions. In order to lay a solid foundation for the study of development-associated division for this organism, a congenic set of mutants was isolated, individually deleted for a gene encoding either a cytoplasmic (i.e. ftsZ) or core inner membrane (i.e. divIC, ftsL, ftsI, ftsQ, ftsW) component of the divisome. While ftsZ mutants are completely blocked for division, single mutants in the other core divisome genes resulted in partial, yet similar, blocks in sporulation septum formation. Double and triple mutants for core divisome membrane components displayed phenotypes that were similar to those of the single mutants, demonstrating that the phenotypes were not synergistic. Division in this organism is still partially functional without multiple core divisome proteins, suggesting that perhaps other unknown lineage-specific proteins perform redundant functions. In addition, by isolating an ftsZ2p mutant with an altered -10 region, the conserved developmentally controlled promoter was also shown to be required for sporulation-associated division. Finally, microscopic observation of FtsZ-YFP dynamics in the different mutant backgrounds led to the conclusion that the initial assembly of regular Z rings does not per se require the tested divisome membrane proteins, but the stability of Z rings is dependent on the divisome membrane components tested. The observation is consistent with the interpretation that Z ring instability likely results from and further contributes to the observed defects in sporulation septation in mutants lacking core divisome proteins.
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| 5. |
- Carlsson, Fredric, et al.
(författare)
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Signal sequence directs localized secretion of bacterial surface proteins.
- 2006
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 442:7105, s. 943-946
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Tidskriftsartikel (refereegranskat)abstract
- All living cells require specific mechanisms that target proteins to the cell surface. In eukaryotes, the first part of this process involves recognition in the endoplasmic reticulum of amino-terminal signal sequences and translocation through Sec translocons, whereas subsequent targeting to different surface locations is promoted by internal sorting signals(1). In bacteria, N-terminal signal sequences promote translocation across the cytoplasmic membrane, which surrounds the entire cell, but some proteins are nevertheless secreted in one part of the cell by poorly understood mechanisms(2,3). Here we analyse localized secretion in the Gram-positive pathogen Streptococcus pyogenes, and show that the signal sequences of two surface proteins, M protein and protein F ( PrtF), direct secretion to different subcellular regions. The signal sequence of M protein promotes secretion at the division septum, whereas that of PrtF preferentially promotes secretion at the old pole. Our work therefore shows that a signal sequence may contain information that directs the secretion of a protein to one subcellular region, in addition to its classical role in promoting secretion. This finding identifies a new level of complexity in protein translocation and emphasizes the potential of bacterial systems for the analysis of fundamental cell-biological problems(4).
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| 6. |
- Del Sol, R, et al.
(författare)
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Influence of CrgA on assembly of the cell division protein FtsZ during development of Streptomyces coelicolor
- 2006
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Ingår i: Journal of Bacteriology. - 0021-9193. ; 188:4, s. 1540-1550
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Tidskriftsartikel (refereegranskat)abstract
- The product of the crgA gene of Streptomyces coelicolor represents a novel family of small proteins. A single orthologous gene is located close to the origin of replication of all fully sequenced actinomycete genomes and borders a conserved gene cluster implicated in cell growth and division. In S. coelicolor, CrgA is important for coordinating growth and cell division in sporogenic hyphae. In this study, we demonstrate that CrgA is an integral membrane protein whose peak expression is coordinated with the onset of development of aerial hyphae. The protein localizes to discrete foci away from growing hyphal tips. Upon overexpression, CrgA localizes to apical syncytial cells of aerial hyphae and inhibits the formation of productive cytokinetic rings of the bacterial tubulin homolog FtsZ, leading to proteolytic turnover of this major cell division determinant. In the absence of known prokaryotic cell division inhibitors in actinomycetes, CrgA may have an important conserved function influencing Z-ring formation in these bacteria.
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| 7. |
- Donczew, Magdalena, et al.
(författare)
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ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation
- 2016
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Ingår i: Open biology. - : The Royal Society. - 2046-2441. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces, ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces. To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB.We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins.
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| 8. |
- Eriksson, Harald, 1977-
(författare)
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Bacterial viruses targeting multi-resistant Klebsiella pneumoniae and Escherichia coli
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The global increase in antibiotic resistance levels in bacteria is a growing concern to our society and highlights the need for alternative strategies to combat bacterial infections. Bacterial viruses (phages) are the natural predators of bacteria and are as diverse as their hosts, but our understanding of them is limited. The current levels of knowledge regarding the role that phage play in the control of bacterial populations are poor, despite the use of phage therapy as a clinical therapy in Eastern Europe.The aim of this doctoral thesis is to increase knowledge of the diversity and characteristics of bacterial viruses and to assess their potential as therapeutic agents towards multi-resistant bacteria.Paper I is the product of de novo sequencing of newly isolated phages that infect and kill multi-resistant Klebsiella pneumoniae. Based on similarities in gene arrangement, lysis cassette type and conserved RNA polymerase, the creation of a new phage genus within Autographivirinae is proposed.Paper II describes the genomic and proteomic analysis of a phage of the rare C3 morphotype, a Podoviridae phage with an elongated head that uses multi-resistant Escherichia coli as its host.Paper III describes the study of a pre-made phage cocktail against 125 clinical K. pneumoniae isolates. The phage cocktail inhibited the growth of 99 (79 %) of the bacterial isolates tested. This study also demonstrates the need for common methodologies in the scientific community to determine how to assess phages that infect multiple serotypes to avoid false positive results.Paper IV studies the effects of phage predation on bacterial virulence: phages were first allowed to prey on a clinical K. pneumoniae isolate, followed by the isolation of phage-resistant bacteria. The phage resistant bacteria were then assessed for their growth rate, biofilm production in vitro. The virulence of the phage resistant bacteria was then assessed in Galleria mellonella. In the single phage treatments, two out of four phages showed an increased virulence in the in G. mellonella, which was also linked to an increased growth rate of the phage resistant bacteria. In multi-phage treatments however, three out of five phage cocktails decreased the bacterial virulence in G. mellonella compared to an untreated control.
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| 9. |
- Flärdh, Klas
(författare)
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Cell polarity and the control of apical growth in Streptomyces.
- 2010
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Ingår i: Current Opinion in Microbiology. - : Elsevier BV. - 1879-0364 .- 1369-5274. ; 13:6, s. 758-765
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Tidskriftsartikel (refereegranskat)abstract
- Streptomyces cells grow by building cell wall at one pole-the hyphal tip. Although analogous to hyphal growth in fungi, this is achieved in a prokaryote, without any of the well-known eukaryotic cell polarity proteins, and it is also unique among bacterial cases of cell polarity. Further, polar growth of Streptomyces and the related mycobacteria and corynebacteria is independent of the MreB cytoskeleton and involves a number of coiled-coil proteins, including the polarity determinant DivIVA. Recent progress sheds light on targeting of DivIVA to hyphal tips and highlight protein phosphorylation in the regulation of actinobacterial growth. Furthermore, cell polarity affects not only cell envelope biogenesis in Streptomyces, but apparently also assembly of fimbriae, conjugation and migration of nucleoids.
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| 10. |
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| 11. |
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| 12. |
- Flärdh, Klas, et al.
(författare)
-
Regulation of apical growth and hyphal branching in Streptomyces
- 2012
-
Ingår i: Current Opinion in Microbiology. - : Elsevier BV. - 1879-0364 .- 1369-5274. ; 15:6, s. 737-743
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Tidskriftsartikel (refereegranskat)abstract
- The filamentous bacteria Streptomyces grow by tip extension and through the initiation of new branches, and this apical growth is directed by a polarisome-like complex involving the essential polarity protein DivIVA. New branch sites must be marked de novo and, until recently, there was no understanding of how these new sites are selected. Equally, hyphal branching patterns are affected by environmental conditions, but there was no insight into how polar growth and hyphal branching might be regulated in response to external or internal cues. This review focuses on recent discoveries that reveal the principal mechanism of branch site selection in Streptomyces, and the first mechanism to be identified that regulates polarisome behaviour to modulate polar growth and hyphal branching.
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| 13. |
- Flärdh, Klas, et al.
(författare)
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Streptomyces morphogenetics: dissecting differentiation in a filamentous bacterium.
- 2009
-
Ingår i: Nature Reviews. Microbiology. - : Springer Science and Business Media LLC. - 1740-1534 .- 1740-1526. ; 7:1, s. 36-49
-
Forskningsöversikt (refereegranskat)abstract
- During the life cycle of the filamentous bacteria Streptomyces, morphological differentiation is closely integrated with fundamental growth and cell-cycle processes, as well as with truly complex multicellular behaviour that involves hormone-like extracellular signalling and coordination with an extraordinarily diverse secondary metabolism. Not only are the bacterial cytoskeleton and the machineries for cell-wall assembly, cell division and chromosome segregation reorganized during sporulation, but the developmental programme of these fascinating organisms also has many unusual elements, including the formation of a sporulating aerial mycelium and the production of a surfactant peptide and a hydrophobic sheath that allow cells to escape from the surface tension of the growth medium.
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| 14. |
- Flärdh, Klas, et al.
(författare)
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The Streptomyces O-B one connection : a force within layered repression of a key developmental decision
- 2017
-
Ingår i: Molecular Microbiology. - : Wiley. - 0950-382X. ; 104:5, s. 695-699
-
Tidskriftsartikel (refereegranskat)abstract
- The study of Streptomyces development has made significant advances in the past few years and ongoing work is poised to add even more. One key to advancing the field has been the application of genome-wide approaches using Streptomyces venezuelae, which is capable of fairly synchronous sporulation in submerged growth conditions. WhiA and WhiB are well-known transcriptional regulators governing the pathway for spore formation in aerial hyphae. Recent ChIP-seq and RNA expression analyses indicated that WhiA and WhiB regulate the same set of genes, each being dependent on the presence of the other to exert control. Functional WhiAB is believed to form when developmental accumulation of WhiB joins constitutive accumulation of WhiA, suggesting that an important developmental decision is the control of WhiB accumulation. Now, a new WhiAB-controlled gene called bldO has been described and characterized. Strikingly, BldO has one target for repression in the entire genome, whiB. BldO now joins pleiotropic repressor BldD to exert a multi-layer control of the temporal and spatial activity of WhiB. BldD activity is controlled by c-di-GMP concentration and BldO potentially responds to an unknown signal. Together BldO and BldD repress developmental genes from being expressed until the appropriate time.
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| 15. |
- Fröjd, Markus J., et al.
(författare)
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Apical assemblies of intermediate filament-like protein FilP are highly dynamic and affect polar growth determinant DivIVA in Streptomyces venezuelae
- 2019
-
Ingår i: Molecular Microbiology. - : Wiley. - 0950-382X .- 1365-2958. ; 112:1
-
Tidskriftsartikel (refereegranskat)abstract
- Streptomyces spp. grow as branching hyphae, building the cell wall in restricted zones at hyphal tips. The organization of this mode of polar growth involves three coiled-coil proteins: DivIVA and Scy, which form apical protein complexes referred to as polarisomes; and the intermediate filament-like protein FilP, which influences cell shape and interacts with both Scy and DivIVA. Here, we use live cell imaging of Streptomyces venezuelae to clarify the subcellular localization and dynamics of FilP and its effect on hyphal morphology. By monitoring a FilP-mCherry fusion protein, we show that FilP accumulates in gradient-like zones behind the hyphal tips. The apical gradient pattern of FilP localization is dependent on hyphal tip extension and immediately dissipates upon growth arrest. Fluorescence recovery after photobleaching experiments show that FilP gradients are dynamic and subject to subunit exchange during vegetative growth. Further, the localization of FilP at hyphal tips is not directly dependent on scy, even though the strongly perturbed morphology of most scy mutant hyphae is associated with mislocalization of FilP. Finally, we find that filP has an effect on the size and position of the foci of key polar growth determinant DivIVA. This effect likely contributes to the phenotype of filP mutants.
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| 16. |
- Fröjd, Markus J., et al.
(författare)
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Extrusion of extracellular membrane vesicles from hyphal tips of streptomyces venezuelae coupled to cell-wall stress
- 2019
-
Ingår i: Microbiology (United Kingdom). - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 165:12, s. 1295-1305
-
Tidskriftsartikel (refereegranskat)abstract
- Extracellular vesicle release is a wide-spread and broadly important phenomenon in bacteria. However, not much is known about the mechanism of vesicle release in Gram-positive bacteria. Observations of polarly growing Streptomyces venezuelae by live cell time-lapse imaging reveal release of extracellular membrane vesicles from tips of vegetative hyphae. Vesicle extrusion is associated with spontaneous growth arrests, but often the apical cell survives and can re-initiate growth by forming new hyphal branches. Treatment with vancomycin to block peptidoglycan synthesis leads to a high frequency of lysis and vesicle extrusion, where some hyphae can survive growth arrest and vesicle extrusion and reinitiate growth after antibiotic is washed away. The extruded vesicles do not contain nucleoids and do not appear able to proliferate. Vesicle extrusion is not affected by the Ser/Thr protein kinase AfsK that phosphorylates the DivIVA at hyphal tips, nor is it affected by the intermediate filament-like protein FilP that localizes in gradient-like structures at hyphal tips. Notably, hyphae of a scy mutant, which has an unstable apical polarisome structure, are prone to spontaneous growth arrests and vesicle extrusion even in the absence of antibiotic treatment, supporting the idea that the nature of the growth zone at the hyphal tips is important for this route of extracellular vesicle formation. We speculate that the propensity for vesicle extrusion is a direct consequence of how polar growth is organized at hyphal tips in Streptomyces, with the cell-wall sacculus being weak and susceptible to bursting at the apical zones of growth where peptidoglycan synthesis is primarily taking place.
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| 17. |
- Fuchino, Katsuya, et al.
(författare)
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Cell-biological studies of osmotic shock response in Streptomyces spp
- 2017
-
Ingår i: Journal of Bacteriology. - 0021-9193. ; 199:1
-
Tidskriftsartikel (refereegranskat)abstract
- Most bacteria are likely to face osmotic challenges, but there is yet much to learn about how such environmental changes affect the architecture of bacterial cells. Here, we report a cell-biological study in model organisms of the genus Streptomyces, which are actinobacteria that grow in a highly polarized fashion to form branching hyphae. The characteristic apical growth of Streptomyces hyphae is orchestrated by protein assemblies, called polarisomes, which contain coiled-coil proteins DivIVA and Scy, and recruit cell wall synthesis complexes and the stressbearing cytoskeleton of FilP to the tip regions of the hyphae. We monitored cell growth and cell-architectural changes by time-lapse microscopy in osmotic upshift experiments. Hyperosmotic shock caused arrest of growth, loss of turgor, and hypercondensation of chromosomes. The recovery period was protracted, presumably due to the dehydrated state of the cytoplasm, before hyphae could restore their turgor and start to grow again. In most hyphae, this regrowth did not take place at the original hyphal tips. Instead, cell polarity was reprogrammed, and polarisomes were redistributed to new sites, leading to the emergence of multiple lateral branches from which growth occurred. Factors known to regulate the branching pattern of Streptomyces hyphae, such as the serine/threonine kinase AfsK and Scy, were not involved in reprogramming of cell polarity, indicating that different mechanisms may act under different environmental conditions to control hyphal branching. Our observations of hyphal morphology during the stress response indicate that turgor and sufficient hydration of cytoplasm are required for Streptomyces tip growth.
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| 18. |
- Fuchino, Katsuya, et al.
(författare)
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Dynamic gradients of an intermediate filament-like cytoskeleton are recruited by a polarity landmark during apical growth
- 2013
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 110:21, s. E1889-E1897
-
Tidskriftsartikel (refereegranskat)abstract
- Intermediate filament (IF)-like cytoskeleton emerges as a versatile tool for cellular organization in all kingdoms of life, underscoring the importance of mechanistically understanding its diverse manifestations. We showed previously that, in Streptomyces (a bacterium with a mycelial lifestyle similar to that of filamentous fungi, including extreme cell and growth polarity), the IF protein FilP confers rigidity to the hyphae by an unknown mechanism. Here, we provide a possible explanation for the IF-like function of FilP by demonstrating its ability to self-assemble into a cis-interconnected regular network in vitro and its localization into structures consistent with a cytoskeletal network in vivo. Furthermore, we reveal that a spatially restricted interaction between FilP and DivIVA, the main component of the Streptomyces polarisome complex, leads to formation of apical gradients of FilP in hyphae undergoing active tip extension. We propose that the coupling between the mechanism driving polar growth and the assembly of an IF cytoskeleton provides each new hypha with an additional stress-bearing structure at its tip, where the nascent cell wall is inevitably more flexible and compliant while it is being assembled and matured. Our data suggest that recruitment of cytoskeleton around a cell polarity landmark is a broadly conserved strategy in tip-growing cells.
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| 19. |
- Grantcharova, Nina, 1974-
(författare)
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Developmental Control of Cell Division in Streptomyces coelicolor
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cell division in the Gram-positive bacterium Streptomyces coelicolor starts with the assembly of the tubulin homologue FtsZ into a cytokinetic ring (the Z ring) at the site of septation. In stark contrast to the binary fission of most bacteria, the syncytial hyphal cells of S. coelicolor exploit two types of cell division with strikingly different outcomes depending on the developmental stage. The main goal of this study has been to identify developmental mechanisms that modulate this differential performance of the basic cell division machinery.By isolation and characterization of a non-sporulating ftsZ mutant, we demonstrated that the requirements for Z-ring formation differ between the two types of septation. The ftsZ17(Spo) mutation abolished septation without overtly affecting vegetative growth. This mutant was defective in the assembly of FtsZ into regularly spaced Z rings in sporogenic hyphae, suggesting that the assembly of Z rings is developmentally controlled during sporulation.An FtsZ-EGFP translational fusion was constructed and used to visualize the progression of FtsZ ring assembly in vivo. This revealed that polymerization of FtsZ occurred throughout the sporogenic cell, with no evidence for pre-determined nucleation sites, and that the placement of multiple Z rings is a dynamic process and involves remodeling of spiral-shaped FtsZ intermediates into regularly spaced rings. The dynamics of the multiple Z-rings assembly during sporulation was perturbed by the action of the protein CrgA, which is important for coordinating growth and cell division in sporogenic hyphae. CrgA was also found to affect the timing of ftsZ expression and the turnover of the FtsZ protein. S. coelicolor is the main genetic model of the streptomycetes, which are major industrial antibiotic producers. The control of cell division in these organisms differs from that of other bacteria like Escherichia coli. Thus, it is of fundamental importance to clarify how the streptomycetes reproduce themselves.
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| 20. |
- Heichlinger, Andrea, et al.
(författare)
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The MreB-like protein Mbl of S. coelicolor A3(2) depends on MreB for proper localization and contributes to spore wall synthesis.
- 2011
-
Ingår i: Journal of Bacteriology. - 0021-9193. ; 193:7, s. 1533-1542
-
Tidskriftsartikel (refereegranskat)abstract
- Most bacteria with a rod-shape morphology contain an actin-like cytoskeleton consisting of MreB polymers which form helical spirals underneath the cytoplasmic membrane to direct peptidoglycan synthesis for elongation of the cell wall. In contrast MreB of Streptomyces coelicolor is not required for vegetative growth, but has a role in sporulation. Beside MreB, S. coelicolor encodes two further MreB-like proteins, Mbl and SCO6166, whose function is unknown. Whereas MreB and Mbl are highly similar, SCO6166 is shorter, lacking the subdomains IB and IIB of actin-like proteins. Here we showed that MreB and Mbl are not functionally redundant but cooperate in spore wall synthesis. Expression analysis by semi-quantitative RT-PCR revealed distinct expression patterns. mreB and mbl are predominantly induced during morphological differentiation. In contrast sco6166 is strongly expressed during vegetative growth but switched off during sporulation. All genes could be deleted without affecting viability. Even a ΔmreB/mbl double mutant was viable. Δsco6166 had a wildtype phenotype. ΔmreB, Δmbl and ΔmreB/mbl produced swollen prematurely germinating spores that were sensitive to various kinds of stress, suggesting a defect in spore wall integrity. During aerial mycelium formation an Mbl-mCherry fusion protein colocalized with an MreB-eGFP fusion protein at the sporulation septa. Whereas MreB-eGFP localized properly in the Δmbl mutant, Mbl-mCherry localization depended on the presence of a functional MreB protein. Our results revealed that MreB and Mbl cooperate in synthesis of the thickened spore wall, while SCO6166 has a non-essential function during vegetative growth.
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| 21. |
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| 22. |
- Hempel, Antje, et al.
(författare)
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The Ser/Thr protein kinase AfsK regulates polar growth and hyphal branching in the filamentous bacteria Streptomyces.
- 2012
-
Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 109:35, s. 2371-2379
-
Tidskriftsartikel (refereegranskat)abstract
- In cells that exhibit apical growth, mechanisms that regulate cell polarity are crucial for determination of cellular shape and for the adaptation of growth to intrinsic and extrinsic cues. Broadly conserved pathways control cell polarity in eukaryotes, but less is known about polarly growing prokaryotes. An evolutionarily ancient form of apical growth is found in the filamentous bacteria Streptomyces, and is directed by a polarisome-like complex involving the essential protein DivIVA. We report here that this bacterial polarization machinery is regulated by a eukaryotic-type Ser/Thr protein kinase, AfsK, which localizes to hyphal tips and phosphorylates DivIVA. During normal growth, AfsK regulates hyphal branching by modulating branch-site selection and some aspect of the underlying polarisome-splitting mechanism that controls branching of Streptomyces hyphae. Further, AfsK is activated by signals generated by the arrest of cell wall synthesis and directly communicates this to the polarisome by hyperphosphorylating DivIVA. Induction of high levels of DivIVA phosphorylation by using a constitutively active mutant AfsK causes disassembly of apical polarisomes, followed by establishment of multiple hyphal branches elsewhere in the cell, revealing a profound impact of this kinase on growth polarity. The function of AfsK is reminiscent of the phoshorylation of polarity proteins and polarisome components by Ser/Thr protein kinases in eukaryotes.
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| 23. |
- Jalalvand, Farshid, et al.
(författare)
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Protein domain-dependent vesiculation of Lipoprotein A, a protein that is important in cell wall synthesis and fitness of the human respiratory pathogen Haemophilus influenzae
- 2022
-
Ingår i: Frontiers in cellular and infection microbiology. - : Frontiers Media SA. - 2235-2988. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The human pathogen Haemophilus influenzae causes respiratory tract infections and is commonly associated with prolonged carriage in patients with chronic obstructive pulmonary disease. Production of outer membrane vesicles (OMVs) is a ubiquitous phenomenon observed in Gram-negative bacteria including H. influenzae. OMVs play an important role in various interactions with the human host; from neutralization of antibodies and complement activation to spread of antimicrobial resistance. Upon vesiculation certain proteins are found in OMVs and some proteins are retained at the cell membrane. The mechanism for this phenomenon is not fully elucidated. We employed mass spectrometry to study vesiculation and the fate of proteins in the outer membrane. Functional groups of proteins were differentially distributed on the cell surface and in OMVs. Despite its supposedly periplasmic and outer membrane location, we found that the peptidoglycan synthase-activator Lipoprotein A (LpoA) was accumulated in OMVs relative to membrane fractions. A mutant devoid of LpoA lost its fitness as revealed by growth and electron microscopy. Furthermore, high-pressure liquid chromatography disclosed a lower concentration (55%) of peptidoglycan in the LpoA-deficient H. influenzae compared to the parent wild type bacterium. Using an LpoA-mNeonGreen fusion protein and fluorescence microscopy, we observed that LpoA was enriched in “foci” in the cell envelope, and further located in the septum during cell division. To define the fate of LpoA, C-terminally truncated LpoA-variants were constructed, and we found that the LpoA C-terminal domain promoted optimal transportation to the OMVs as revealed by flow cytometry. Taken together, our study highlights the importance of LpoA for H. influenzae peptidoglycan biogenesis and provides novel insights into cell wall integrity and OMV production.
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| 24. |
- Javadi, Ala, et al.
(författare)
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Assembly mechanisms of the bacterial cytoskeletal protein FilP
- 2019
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Ingår i: Life Science Alliance. - : Life Science Alliance. - 2575-1077. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- Despite low-sequence homology, the intermediate filament (IF)–like protein FilP from Streptomyces coelicolor displays structural and biochemical similarities to the metazoan nuclear IF lamin. FilP, like IF proteins, is composed of central coiled-coil domains interrupted by short linkers and flanked by head and tail domains. FilP polymerizes into repetitive filament bundles with paracrystalline properties. However, the cations Na+ and K+ are found to induce the formation of a FilP hexagonal meshwork with the same 60-nm repetitive unit as the filaments. Studies of polymerization kinetics, in combination with EM techniques, enabled visualization of the basic building block — a transiently soluble rod-shaped FilP molecule—and its assembly into protofilaments and filament bundles. Cryoelectron tomography provided a 3D view of the FilP bundle structure and an original assembly model of an IF-like protein of prokaryotic origin, thereby enabling a comparison with the assembly of metazoan IF.
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| 25. |
- Jurásek, Miroslav, et al.
(författare)
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Effect of membrane composition on DivIVA-membrane interaction
- 2020
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier BV. - 0005-2736. ; 1862:8
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Tidskriftsartikel (refereegranskat)abstract
- DivIVA is a crucial membrane-binding protein that helps to localize other proteins to negatively curved membranes at cellular poles and division septa in Gram-positive bacteria. The N-terminal domain of DivIVA is responsible for membrane binding. However, to which lipids the domain binds or how it recognizes the membrane negative curvature remains elusive. Using computer simulations, we demonstrate that the N-terminal domain of Streptomyces coelicolor DivIVA adsorbs to membranes with affinity and orientation dependent on the lipid composition. The domain interacts non-specifically with lipid phosphates via its arginine-rich tip and the strongest interaction is with cardiolipin. Moreover, we observed a specific attraction between a negatively charged side patch of the domain and ethanolamine lipids, which addition caused the change of the domain orientation from perpendicular to parallel alignment to the membrane plane. Similar but less electrostatically dependent behavior was observed for the N-terminal domain of Bacillus subtilis. The domain propensity for lipids which prefer negatively curved membranes could be a mechanism for the cellular localization of DivIVA protein.
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