| 1. |
- Bukowska-Faniband, Ewa, et al.
(författare)
-
Cortex synthesis during Bacillus subtilis sporulation depends on the transpeptidase activity of SpoVD.
- 2013
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 346:1, s. 65-72
-
Tidskriftsartikel (refereegranskat)abstract
- The nonessential process of peptidoglycan synthesis during Bacillus subtilis sporulation is one model to study bacterial cell wall biogenesis. SpoVD is a class B high-molecular weight penicillin-binding protein that is specific for sporulation. Strains lacking this protein produce spores without the peptidoglycan cortex layer and are heat-sensitive. The detailed functions of the four different protein domains of the SpoVD protein are unknown and the observed phenotype of strains lacking the entire protein could be an indirect defect. We therefore inactivated the transpeptidase domain by substitution of the active site serine residue. Our results demonstrate that endospore cortex synthesis depends on the transpeptidase activity of SpoVD specifically. This article is protected by copyright. All rights reserved.
|
|
| 2. |
- Cousin, C., et al.
(författare)
-
Protein-serine/threonine/tyrosine kinases in bacterial signaling and regulation
- 2013
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 346:1, s. 11-19
-
Forskningsöversikt (refereegranskat)abstract
- In this review, we address some recent developments in the field of bacterial protein phosphorylation, focusing specifically on serine/threonine and tyrosine kinases. We present an overview of recent studies outlining the scope of physiological processes that are regulated by phosphorylation, ranging from cell cycle, growth, cell morphology, to metabolism, developmental phenomena, and virulence. Specific emphasis is placed on Mycobacterium tuberculosis as a showcase organism for serine/threonine kinases, and Bacillus subtilis to illustrate the importance of protein phosphorylation in developmental processes. We argue that bacterial serine/threonine and tyrosine kinases have a distinctive feature of phosphorylating multiple substrates and might thus represent integration nodes in the signaling network. Some open questions regarding the evolutionary benefits of relaxed substrate selectivity of these kinases are treated, as well as the notion of nonfunctional background' phosphorylation of cellular proteins. We also argue that phosphorylation events for which an immediate regulatory effect is not clearly established should not be dismissed as unimportant, as they may have a role in cross-talk with other post-translational modifications. Finally, recently developed methods for studying protein phosphorylation networks in bacteria are briefly discussed.
|
|
| 3. |
- Patel, Ami, et al.
(författare)
-
Evidence for xylooligosaccharides utilization in Weissella strains isolated from Indian fermented foods and vegetables.
- 2013
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 346:1, s. 20-28
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Six strains isolated from fermented food were by 16S rDNA sequencing identified as Weissella species, clustering with the species-pair W. confusa/ W. cibaria. The strains were analysed for growth on glucose, xylose and xylooligosaccharides (XOS). All strains were xylose positive using the API CHL 50 test. Growth on XOS was observed for strain 85, 92, 145 and AV1, firstly by optical density measurements in microtiter plates and secondly in batch cultures also confirming concomitant decrease in pH. Analysis of XOS before and after growth established consumption in the DP2 - DP5 range in the four XOS-fermenting strains. XOS were consumed simultaneously with glucose, while xylose was consumed after glucose depletion. Cell-associated β-xylosidase activity was detected in the XOS fermenting strains. Analysis of genomic data suggests this activity to be linked to genes encoding glycoside hydrolases from family 3, 8 or 43. No endo-β-xylanase activity was detectable. Main fermentation end products were lactate and acetate. A higher ratio of acetic acid/lactic acid was produced during growth on XOS compared to growth on glucose. This is the first report on utilization of XOS in Weissella, indicating an increased probiotic potential for XOS-utilizing strains from the species pair W. confusa/ W. cibaria, but also showing that XOS utilization is strain-dependent for these species. This article is protected by copyright. All rights reserved.
|
|
| 4. |
- Persson, Jessica, et al.
(författare)
-
Molecular and cytological analysis of the expression of Streptomyces sporulation regulatory gene whiH.
- 2013
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 341:2, s. 96-105
-
Tidskriftsartikel (refereegranskat)abstract
- The whiH gene is required for the orderly sporulation septation that divides aerial hyphae into spores in Streptomyces coelicolor. Here, we use a whiHp-mCherry transcriptional reporter construct to show that whiHp is active specifically in aerial hyphae, fluorescence being dependent on sporulation sigma factor WhiG. The results show that the promoter is active before the septation event that separates the sub-apical compartment from the tip compartment destined to become a spore chain. We conclude that WhiG-directed RNA polymerase activity, which is required for whiH transcription, must precede this septation event and is not restricted to apical sporogenic compartment of the aerial hyphae. Further, it is demonstrated that WhiH, a predicted member of the GntR family of transcription factors, is able to bind specifically to a sequence in its own promoter, strongly suggesting that it acts as an autoregulatory transcription factor. Finally, we show by site-directed mutagenesis and a genetic complementation test that whiH is translated from a start codon overlapping with the previously identified transcription start point, implying leaderless transcription.
|
|
| 5. |
- Prosser, J. I., et al.
(författare)
-
Most influential FEMS publications
- 2014
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 354:2, s. 83-84
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 6. |
- Ahrén, Dag, et al.
(författare)
-
Phylogeny of nematode-trapping fungi based on 18S rDNA sequences
- 1998
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 158:2, s. 179-184
-
Tidskriftsartikel (refereegranskat)abstract
- The small subunit (SSU) ribosomal DNA (18S rDNA) from 15 species of nematode-trapping fungi and closely related non-parasitic species were sequenced. Phylogenetic analysis indicated that species within the genera of Arthrobotrys, Dactylaria, Dactylella, Monacrosporium and Duddingtonia formed a monophyletic and isolated clade among an unresolved cluster of apothecial ascomycetes. The phylogenetic patterns within this clade were not concordant with the morphology of the conidia nor the conidiophores, but rather with that of the infection structures. The results from the different methods of tree reconstruction supported three lineages; the species having constricting rings, the non-parasitic species and the species having various adhesive structures (nets, hyphae, knobs and non-constricting rings) to infect nematodes.
|
|
| 7. |
- Ambalam, Padma, et al.
(författare)
-
Bile stimulates Cell Surface Hydrophobicity, Congo Red Binding and Biofilm Formation of Lactobacillus strains.
- 2012
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 333:1, s. 10-19
-
Tidskriftsartikel (refereegranskat)abstract
- Seventeen Lactobacillus strains were tested for cell surface hydrophobicity (CSH) using the salt aggregation test (SAT) and Congo red binding (CRB) assay. CRB was pH and ionic strength dependent and protease sensitive and in the presence of 100 μg/ml cholesterol, the CRB was significantly reduced. Autoaggregating (AA) L. crispatus strains showed 50% more CRB than the reference strain, the curli-producing E.coli MC4100. CRB of L. crispatus 12005, L. paracasei F8, L. plantarum F44 and L. paracasei F19 was enhanced when grown in MRS broth with 0.5% taurocholic acid (TA) or 5% porcine bile (PB) (P<0.05). CSH was also enhanced for the non-AA strains, L. plantarum F44, L. paracasei F19 and L. rhamnosus GG when grown in MRS broth with 0.5% TA, 5% PB or 0.25% mucin with enhanced biofilm formation in MRS broth with bile (P<0.05). Two AA strains, L. crispatus 12005 and L. paracasei F8, developed biofilm independent of bile or mucin. In summary, under bile stressed growth conditions, early (24 h cultures) biofilm formation is associated with an increase in hydrophobic cell surface proteins and high CRB. Late mature (72 h culture) biofilm contained more carbohydrates as shown by crystal violet staining. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd.All rights reserved.
|
|
| 8. |
- Baureder, Michael, et al.
(författare)
-
Contribution of catalase to hydrogen peroxide resistance in Enterococcus faecalis.
- 2012
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 331:2, s. 160-164
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Enterococcus faecalis exhibits high resistance to oxidative stress. Several enzymes are responsible for this trait. The role of alkyl hydroperoxide reductase (Ahp), thiol peroxidase (Tpx), and NADH peroxidase (Npr) in oxidative stress defense was recently characterized. Enterococcus faecalis, in contrast to many other streptococci, contains a catalase (KatA), but this enzyme can only be formed when the bacterium is supplied with heme. We have used this heme dependency of catalase activity and mutants deficient in KatA and Npr to investigate the role of the catalase in resistance against exogenous and endogenous hydrogen peroxide stress. The results demonstrate that in the presence of environmental heme catalase contributes to the protection against toxic effects of hydrogen peroxide.
|
|
| 9. |
- Bielen, Abraham A. M., et al.
(författare)
-
Pyrophosphate as a central energy carrier in the hydrogen-producing extremely thermophilic Caldicellulosiruptor saccharolyticus
- 2010
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 307:1, s. 48-54
-
Tidskriftsartikel (refereegranskat)abstract
- The role of inorganic pyrophosphate (PPi) as an energy carrier in the central metabolism of the extremely thermophilic bacterium Caldicellulosiruptor saccharolyticus was investigated. In agreement with its annotated genome sequence, cell extracts were shown to exhibit PPi-dependent phosphofructokinase and pyruvate phosphate dikinase activity. In addition, membrane-bound pyrophosphatase activity was demonstrated, while no significant cytosolic pyrophosphatase activity was detected. During the exponential growth phase, high PPi levels (approximately 4 +/- 2 mM) and relatively low ATP levels (0.43 +/- 0.07 mM) were found, and the PPi/ATP ratio decreased 13-fold when the cells entered the stationary phase. Pyruvate kinase activity appeared to be allosterically affected by PPi. Altogether, these findings suggest an important role for PPi in the central energy metabolism of C. saccharolyticus.
|
|
| 10. |
- Bos, R., et al.
(författare)
-
Retention of bacteria on a substratum surface with micro-patterned hydrophobicity
- 2000
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 189:2, s. 311-315
-
Tidskriftsartikel (refereegranskat)abstract
- Bacteria adhere to almost any surface, despite continuing arguments about the importance of physico-chemical properties of substratum surfaces, such as hydrophobicity and charge in biofilm formation. Nevertheless, in vivo biofilm formation on teeth and also on voice prostheses in laryngectomized patients is less on hydrophobic than on hydrophilic surfaces. With the aid of micro-patterned surfaces consisting of 10-mu m wide hydrophobic lines separated by 20-mu m wide hydrophilic spacings, we demonstrate here, For the first time in one and the same experiment, that bacteria do not have a strong preference for adhesion to hydrophobic or hydrophilic surfaces. Upon challenging the adhering bacteria, after deposition in a parallel plate flow chamber, with a high detachment force, however, bacteria were easily wiped-off hydrophobic lines, most notably when these lines were oriented parallel to the direction of flow. Adhering bacteria detached slightly less from the hydrophilic spacings in between, but preferentially accumulated adhering on the hydrophilic regions close to the interface between the hydrophilic spacings and hydrophobic lines. It is concluded that substratum hydrophobicity is a major determinant of bacterial retention while it hardly influences bacterial adhesion.
|
|
