Control of the bifunctional O2‐sensor kinase NreB of Staphylococcus carnosus by the nitrate sensor NreA: Switching from kinase to phosphatase state. Issue 2 (12th December 2019)

• Record Type: Journal Article
• Authors: Klein, Robin; Kretzschmar, Ann‐Katrin; Unden, Gottfried
• Is Part Of: Molecular microbiology. Volume 113:Issue 2(2019)
• Page Start: 369
• Page End: 380
• Publication Date: 2019-12-12
• Subjects: bifunctional sensor kinase -- NreB -- NreA -- nitrate regulation -- phosphatase -- Staphylococcus carnosus; Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.14425
• Languages: English
• ISSNs: 0950-382X

Abstract

Abstract: The NreB–NreC two‐component system of Staphylococcus carnosus for O2 sensing cooperates with the accessory nitrate sensor NreA in the NreA–NreB–NreC system for coordinated sensing and regulation of nitrate respiration by O2 and nitrate. ApoNreA (NreA in the absence of nitrate) interacts with NreB and inhibits NreB autophosphorylation (and activation). NreB contains the phosphatase motif DxxxQ. The present study shows that NreB on its own was inactive for the dephosphorylation of the phosphorylated response regulator NreC (NreC‐P), but co‐incubation with NreB and NreA stimulated NreC‐P dephosphorylation. Either the presence of NreA · NO 3 - instead of apoNreA or mutation of the phosphatase motif (D160 or Q164) of NreB abrogated phosphatase activity of NreB. Phosphatase activity was observed for anoxic (active) NreB as well as oxic NreB, therefore the functional state of NreB is not relevant for phosphatase activity. Thus, NreB is a bifunctional sensor kinase with an integral cryptic phosphatase activity. Activation of phosphatase activity and dephosphorylation of NreC‐P requires NreA as a cofactor. Accordingly, NreA and nitrate have major and dual roles in NreA–NreB–NreC regulation by (i) inhibiting NreB phosphorylation and (ii) triggering a kinase/phosphatase switch of NreB when present as apoNreA. Abstract : In Staphylococci, nitrate metabolism is subject to nitrate and oxygen regulation by the extended two‐component system NreA‐NreB‐NreC. The sensor kinase NreB is regulated in addition to O2 by nitrate via the nitrate sensor NreA. Nitrate‐depleted NreA inhibits NreB auto‐phosphorylation and stimulates a cryptic phosphatase in NreB; both reactions are reversed by nitrate. The nitrate/NreA regulated switching of NreB from the kinase to the phosphatase state represents a new mechanism for nitrate sensing and regulation.