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- Derouiche, Abderahmane, 1980, et al.
(author)
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Bacillus subtilisSalA is a phosphorylation-dependent transcription regulator that represses scoC and activates the production of the exoprotease AprE
- 2015
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In: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 97:6, s. 1195-1208
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Journal article (peer-reviewed)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.
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| 2. |
- Derouiche, A., et al.
(author)
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Interaction of bacterial fatty-acid-displaced regulators with DNA is interrupted by tyrosine phosphorylation in the helix-turn-helix domain
- 2013
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In: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 41:20, s. 9371-9381
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Journal article (peer-reviewed)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.
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