| 1. |
- Kalantari, Aida, 1986, et al.
(författare)
-
Conversion of Glycerol to 3-Hydroxypropanoic Acid by Genetically Engineered Bacillus subtilis
- 2017
-
Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 8:APR
-
Tidskriftsartikel (refereegranskat)abstract
- 3-Hydroxypropanoic acid (3-HP) is an important biomass-derivable platform chemical that can be converted into a number of industrially relevant compounds. There have been several attempts to produce 3-HP from renewable sources in cell factories, focusing mainly on Escherichia coli, Klebsiella pneumoniae, and Saccharomyces cerevisiae. Despite the significant progress made in this field, commercially exploitable large-scale production of 3-HP in microbial strains has still not been achieved. In this study, we investigated the potential of Bacillus subtilis as a microbial platform for bioconversion of glycerol into 3-HP. Our recombinant B. subtilis strains overexpress the two-step heterologous pathway containing glycerol dehydratase and aldehyde dehydrogenase from K. pneumoniae. Genetic engineering, driven by in silico optimization, and optimization of cultivation conditions resulted in a 3-HP titer of 10 g/L, in a standard batch cultivation. Our findings provide the first report of successful introduction of the biosynthetic pathway for conversion of glycerol into 3-HP in B. subtilis. With this relatively high titer in batch, and the robustness of B. subtilis in high density fermentation conditions, we expect that our production strains may constitute a solid basis for commercial production of 3-HP.
|
|
| 2. |
- Shi, Lei, 1981, et al.
(författare)
-
Evolutionary Analysis of the Bacillus subtilis Genome Reveals New Genes Involved in Sporulation
- 2020
-
Ingår i: Molecular biology and evolution. - : Oxford University Press. - 0737-4038 .- 1537-1719. ; 37:6, s. 1667-1678
-
Tidskriftsartikel (refereegranskat)abstract
- Bacilli can form dormant, highly resistant, and metabolically inactive spores to cope with extreme environmental challenges. In this study, we examined the evolutionary age of Bacillus subtilis sporulation genes using the approach known as genomic phylostratigraphy. We found that B. subtilis sporulation genes cluster in several groups that emerged at distant evolutionary time-points, suggesting that the sporulation process underwent several stages of expansion. Next, we asked whether such evolutionary stratification of the genome could be used to predict involvement in sporulation of presently uncharacterized genes (y-genes). We individually inactivated a representative sample of uncharacterized genes that arose during the same evolutionary periods as the known sporulation genes and tested the resulting strains for sporulation phenotypes. Sporulation was significantly affected in 16 out of 37 (43%) tested strains. In addition to expanding the knowledge base on B. subtilis sporulation, our findings suggest that evolutionary age could be used to help with genome mining.
|
|
| 3. |
- Derouiche, Abderahmane, 1980, et al.
(författare)
-
Bacillus subtilisSalA is a phosphorylation-dependent transcription regulator that represses scoC and activates the production of the exoprotease AprE
- 2015
-
Ingår i: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 97:6, s. 1195-1208
-
Tidskriftsartikel (refereegranskat)abstract
- Bacillus subtilisMrp family protein SalA has been shown to indirectly promote the production of the exoprotease AprE by inhibiting the expression of scoC, which codes for a repressor of aprE. The exact mechanism by which SalA influences scoC expression has not been clarified previously. We demonstrate that SalA possesses a DNA-binding domain (residues 1-60), which binds to the promoter region of scoC. The binding of SalA to its target DNA depends on the presence of ATP and is stimulated by phosphorylation of SalA at tyrosine 327. The B.subtilis protein-tyrosine kinase PtkA interacts specifically with the C-terminal domain of SalAin vivo and in vitro and is responsible for activating its DNA binding via phosphorylation of tyrosine 327. In vivo, a mutant mimicking phosphorylation of SalA (SalA Y327E) exhibited a strong repression of scoC and consequently overproduction of AprE. By contrast, the non-phosphorylatable SalA Y327F and the ΔptkA exhibited the opposite effect, stronger expression of scoC and lower production of the exoprotease. Interestingly, both SalA and PtkA contain the same ATP-binding Walker domain and have thus presumably arisen from the common ancestral protein. Their regulatory interplay seems to be conserved in other bacteria.
|
|
| 4. |
- Derouiche, Abderahmane, 1980, et al.
(författare)
-
Evolution and tinkering: what do a protein kinase, a transcriptional regulator and chromosome segregation/cell division proteins have in common?
- 2016
-
Ingår i: Current Genetics. - : Springer Science and Business Media LLC. - 0172-8083 .- 1432-0983. ; 62:1, s. 67-70
-
Forskningsöversikt (refereegranskat)abstract
- In this study, we focus on functional interactions among multi-domain proteins which share a common evolutionary origin. The examples we develop are four Bacillus subtilis proteins, which all possess an ATP-binding Walker motif: the bacterial tyrosine kinase (BY-kinase) PtkA, the chromosome segregation protein Soj (ParA), the cell division protein MinD and a transcription regulator SalA. These proteins have arisen via duplication of the ancestral ATP-binding domain, which has undergone fusions with other functional domains in the process of divergent evolution. We point out that these four proteins, despite having very different physiological roles, engage in an unusually high number of binary functional interactions. Namely, MinD attracts Soj and PtkA to the cell pole, and in addition, activates the kinase function of PtkA. SalA also activates the kinase function of PtkA, and it gets phosphorylated by PtkA as well. The consequence of this phosphorylation is the activation of SalA as a transcriptional repressor. We hypothesize that these functional interactions remain preserved during divergent evolution and represent a constraint on the process of evolutionary "tinkering", brought about by fusions of different functional domains.
|
|
| 5. |
- Derouiche, Abderahmane, 1980, et al.
(författare)
-
Substrate Specificity of the Bacillus subtilis BY-Kinase PtkA Is Controlled by Alternative Activators: TkmA and SalA
- 2016
-
Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 7:SEP
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial protein-tyrosine kinases (BY-kinases) are known to regulate different aspects of bacterial physiology, by phosphorylating cellular protein substrates. Physiological cues that trigger BY-kinases activity are largely unexplored. In Proteobacteria, BY-kinases contain a cytosol-exposed catalytic domain and a transmembrane activator domain in a single polypeptide chain. In Firrnicutes, the BY-kinase catalytic domain and the transmembrane activator domain exist as separate polypeptides. We have previously speculated that this architecture might enable the Firmicutes BY-kinases to interact with alternative activators, and thus account for the observed ability of these kinases to phosphorylate several distinct classes of protein substrates. Here, we present experimental evidence that supports this hypothesis. We focus on the model Firmicute-type BY-kinase PtkA from Bacillus subtilis, known to phosphorylate several different protein substrates. We demonstrate that the transcriptional regulator SaIA, hitherto known as a substrate of PtkA, can also act as a PtkA activator. In doing so, SaIA competes with the canonical PtkA activator, TkmA. Our results suggest that the respective interactions of SaIA and TkmA with PtkA favor phosphorylation of different protein substrates in vivo and in vitro. This observation may contribute to explaining how specificity is established in the seemingly promiscuous interactions of BY-kinases with their cellular substrates.
|
|
| 6. |
- Garg, Abhroop, et al.
(författare)
-
Engineering Bacillus subtilis for production of 3-hydroxypropanoic acid
- 2023
-
Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media SA. - 2296-4185. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- 3-Hydroxypropionic acid (3-HP) is a valuable platform chemical that is used as a precursor for several higher value-added chemical products. There is an increased interest in development of cell factories as a means for the synthesis of 3-HP and various other platform chemicals. For more than a decade, concentrated effort has been invested by the scientific community towards developing bio-based approaches for the production of 3-HP using primarily Escherichia coli and Klebsiella pneumoniae as production hosts. These hosts however might not be optimal for applications in e.g., food industry due primarily to endotoxin production and the pathogenic origin of particularly the K. pneumoniae. We have previously demonstrated that the generally recognized as safe organism Bacillus subtilis can be engineered to produce 3-HP using glycerol, an abundant by-product of the biodiesel industry, as substrate. For commercial exploitation, there is a need to substantially increase the titer. In the present study, we optimized the bioprocess conditions and further engineered the B. subtilis 3-HP production strain. Thereby, using glycerol as substrate, we were able to improve 3-HP production in a 1-L bioreactor to a final titer of 22.9 g/L 3-HP.
|
|
| 7. |
- Jers, C., et al.
(författare)
-
Production of 3-hydroxypropanoic acid from glycerol by metabolically engineered bacteria
- 2019
-
Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media SA. - 2296-4185. ; 7:MAY
-
Forskningsöversikt (refereegranskat)abstract
- 3-hydroxypropanoic acid (3-HP) is a valuable platform chemical with a high demand in the global market. 3-HP can be produced from various renewable resources. It is used as a precursor in industrial production of a number of chemicals, such as acrylic acid and its many derivatives. In its polymerized form, 3-HP can be used in bioplastic production. Several microbes naturally possess the biosynthetic pathways for production of 3-HP, and a number of these pathways have been introduced in some widely used cell factories, such as Escherichia coli and Saccharomyces cerevisiae. Latest advances in the field of metabolic engineering and synthetic biology have led to more efficient methods for bio-production of 3-HP. These include new approaches for introducing heterologous pathways, precise control of gene expression, rational enzyme engineering, redirecting the carbon flux based on in silico predictions using genome scale metabolic models, as well as optimizing fermentation conditions. Despite the fact that the production of 3-HP has been extensively explored in established industrially relevant cell factories, the current production processes have not yet reached the levels required for industrial exploitation. In this review, we explore the state of the art in 3-HP bio-production, comparing the yields and titers achieved in different microbial cell factories and we discuss possible methodologies that could make the final step toward industrially relevant cell factories.
|
|
| 8. |
- Kalantari, Aida, 1986, et al.
(författare)
-
Serine/threonine/tyrosine phosphorylation regulates DNA binding of bacterial transcriptional regulators
- 2015
-
Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 161:9, s. 1720-1729
-
Forskningsöversikt (refereegranskat)abstract
- Reversible phosphorylation of bacterial transcriptional regulators (TRs) belonging to the family of two-component systems (TCSs) is a well-established mechanism for regulating gene expression. Recent evidence points to the fact that reversible phosphorylation of bacterial TRs on other types of residue, i.e. serine, threonine, tyrosine and cysteine, is also quite common. The phosphorylation of the ester type (phospho-serine/threonine/tyrosine) is more stable than the aspartate phosphorylation of TCSs. The kinases which catalyse these phosphorylation events (Hanks-type serine/threonine protein kinases and bacterial protein tyrosine kinases) are also much more promiscuous than the TCS kinases, i.e. each of them can phosphorylate several substrate proteins. As a consequence, the dynamics and topology of the signal transduction networks depending on these kinases differ significantly from the TCSs. Here, we present an overview of different classes of bacterial TR phosphorylated and regulated by serine/threonine and tyrosine kinases. Particular attention is given to examples when serine/threonine and tyrosine kinases interact with TCSs, phosphorylating either the histidine kinases or the response regulators. We argue that these promiscuous kinases connect several signal transduction pathways and serve the role of signal integration.
|
|
