| 1. |
- 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.
|
|
| 2. |
- Derouiche, A., et al.
(författare)
-
Interaction of bacterial fatty-acid-displaced regulators with DNA is interrupted by tyrosine phosphorylation in the helix-turn-helix domain
- 2013
-
Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 41:20, s. 9371-9381
-
Tidskriftsartikel (refereegranskat)abstract
- Bacteria possess transcription regulators (of the TetR family) specifically dedicated to repressing genes for cytochrome P450, involved in oxidation of polyunsaturated fatty acids. Interaction of these repressors with operator sequences is disrupted in the presence of fatty acids, and they are therefore known as fatty-acid-displaced regulators. Here, we describe a novel mechanism of inactivating the interaction of these proteins with DNA, illustrated by the example of Bacillus subtilis regulator FatR. FatR was found to interact in a two-hybrid assay with TkmA, an activator of the protein-tyrosine kinase PtkA. We show that FatR is phosphorylated specifically at the residue tyrosine 45 in its helix-turn-helix domain by the kinase PtkA. Structural modelling reveals that the hydroxyl group of tyrosine 45 interacts with DNA, and we show that this phosphorylation reduces FatR DNA binding capacity. Point mutants mimicking phosphorylation of FatR in vivo lead to a strong derepression of the fatR operon, indicating that this regulatory mechanism works independently of derepression by polyunsaturated fatty acids. Tyrosine 45 is a highly conserved residue, and PtkA from B. subtilis can phosphorylate FatR homologues from other bacteria. This indicates that phosphorylation of tyrosine 45 may be a general mechanism of switching off bacterial fatty-acid-displaced regulators.
|
|
| 3. |
- Kobir, A., et al.
(författare)
-
Phosphorylation of Bacillus subtilis gene regulator AbrB modulates its DNA-binding properties
- 2014
-
Ingår i: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 92:5, s. 1129-1141
-
Tidskriftsartikel (refereegranskat)abstract
- AbrB is a global gene regulator involved in transition phase phenomena in Bacillus subtilis. It participates in a complex regulatory network governing the expression of stationary-phase functions. AbrB was previously found to be phosphorylated on serine 86 located close to its C-terminal oligomerization domain. Here we report that AbrB can be phosphorylated by three B. subtilis serine/threonine kinases expressed during the transition and stationary phase: PrkC, PrkD and YabT. Our in vitro findings suggest that AbrB phosphorylation impedes its DNA binding and abolishes binding cooperativity. In vivo we established that a phospho-mimetic mutation abrB S86D leads to a significant loss of AbrB control over several key target functions: exoprotease production, competence development and sporulation. A wider transcriptome analysis of abrBS86D and S86A mutant strains revealed deregulation of a large number of target genes. We therefore propose that AbrB phosphorylation serves as an additional input for fine-tuning the activity of this ambiactive gene regulator.
|
|
| 4. |
- Shi, Lei, 1981, et al.
(författare)
-
Protein-tyrosine phosphorylation interaction network in Bacillus subtilis reveals new substrates, kinase activators and kinase cross-talk
- 2014
-
Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 5:OCT, s. Art. no. 538-
-
Tidskriftsartikel (refereegranskat)abstract
- Signal transduction in eukaryotes is generally transmitted through phosphorylation cascades that involve a complex interplay of transmembrane receptors, protein kinases, phosphatases and their targets. Our previous work indicated that bacterial protein-tyrosine kinases and phosphatases may exhibit similar properties, since they act on many different substrates. To capture the complexity of this phosphorylation-based network, we performed a comprehensive interactome study focused on the protein-tyrosine kinases and phosphatases in the model bacterium Bacillus subtilis. The resulting network identified many potential new substrates of kinases and phosphatases, some of which were experimentally validated. Our study highlighted the role of tyrosine and serine/threonine kinases and phosphatases in DNA metabolism, transcriptional control and cell division. This interaction network reveals significant crosstalk among different classes of kinases. We found that tyrosine kinases can bind to several modulators, transmembrane or cytosolic, consistent with a branching of signaling pathways. Most particularly, we found that the division site regulator MinD can form a complex with the tyrosine kinase PtkA and modulate its activity in vitro. In vivo, it acts as a scaffold protein which anchors the kinase at the cell pole. This network highlighted a role of tyrosine phosphorylation in the spatial regulation of the Z-ring during cytokinesis.
|
|
