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Thiol redox switches regulate the oligomeric state of cyanobacterial Rre1, RpaA and RpaB response regulators.

ABSTRACT: Cyanobacteria employ two-component sensor-response regulator systems to monitor and respond to environmental challenges. The response regulators RpaA, RpaB, Rre1 and RppA are integral to circadian clock function and abiotic stress acclimation in cyanobacteria. RpaA, RpaB and Rre1 are known to interact with ferredoxin or thioredoxin, raising the possibility of their thiol regulation. Here, we report that Synechocystis sp. PCC 6803 Rre1, RpaA and RpaB exist as higher-order oligomers under oxidising conditions and that reduced thioredoxin A converts them to monomers. We further show that these response regulators contain redox-responsive cysteine residues with an E_m7 around -300 mV. These findings suggest a direct thiol modulation of the activity of these response regulators, independent of their cognate sensor kinases.

SUBMITTER: Ibrahim IM

PROVIDER: S-EPMC9321951 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Thiol redox switches regulate the oligomeric state of cyanobacterial Rre1, RpaA and RpaB response regulators.

Ibrahim Iskander M IM Rowden Stephen J L SJL Cramer William A WA Howe Christopher J CJ Puthiyaveetil Sujith S

FEBS letters 20220411 12

Cyanobacteria employ two-component sensor-response regulator systems to monitor and respond to environmental challenges. The response regulators RpaA, RpaB, Rre1 and RppA are integral to circadian clock function and abiotic stress acclimation in cyanobacteria. RpaA, RpaB and Rre1 are known to interact with ferredoxin or thioredoxin, raising the possibility of their thiol regulation. Here, we report that Synechocystis sp. PCC 6803 Rre1, RpaA and RpaB exist as higher-order oligomers under oxidisin ...[more]

PMID: 35353903

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