A putative bifunctional histidine kinase/phosphatase of the HWE family exerts positive and negative control on the Sinorhizobium meliloti general stress response. - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Journal of Bacteriology Année : 2014

A putative bifunctional histidine kinase/phosphatase of the HWE family exerts positive and negative control on the Sinorhizobium meliloti general stress response.

Claude Bruand

Résumé

The EcfG-type sigma factor RpoE2 is the regulator of the general stress response in Sinorhizobium meliloti. RpoE2 activity is negatively regulated by two NepR-type anti-sigma factors (RsiA1/A2), themselves under control of two anti-anti-sigma factors (RsiB1/B2) belonging to the PhyR family of response regulators. The current model of RpoE2 activation suggests that in response to stress, RsiB1/B2 are activated by phosphorylation of an aspartate residue in their receiver domain. Once activated, RsiB1/B2 become able to interact with the anti-sigma factors and thus release RpoE2, which can then associate with the RNA polymerase to transcribe its target genes. The purpose of this work was to identify and characterize proteins involved in controlling the phosphorylation status of RsiB1/B2. Using in vivo approaches, we show that the putative histine kinase encoded by the rsiC gene (SMc01507), located downstream from rpoE2, is able to both positively and negatively regulate the general stress response. In addition, our data suggest that the negative action of RsiC results from inhibition of RsiB1/B2 phosphorylation. From these observations, we propose that RsiC is a bifunctional histidine kinase/phosphatase responsible for RsiB1/B2 phosphorylation or dephosphorylation in the presence or absence of stress, respectively. Two proteins were previously proposed to control PhyR phosphorylation in Caulobacter crescentus and Sphingomonas sp. FR1. However, these proteins contain a Pfam:HisKA_2 domain of dimerization and histidine phosphotransfer, whereas S. meliloti RsiC harbors a Pfam:HWE_HK domain instead. This is therefore the first report of a HWE_HK-containing protein controlling the general stress response in α-Proteobacteria.

Dates et versions

hal-02640546 , version 1 (28-05-2020)

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Citer

Laurent Sauviac, Claude Bruand. A putative bifunctional histidine kinase/phosphatase of the HWE family exerts positive and negative control on the Sinorhizobium meliloti general stress response.. Journal of Bacteriology, 2014, 196 (14), pp.2526-2535. ⟨10.1128/JB.01623-14⟩. ⟨hal-02640546⟩
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