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Thiol redox switches regulate the oligomeric state of cyanobacterial Rre1, RpaA and RpaB response regulators
Author(s) -
Ibrahim Iskander M.,
Rowden Stephen J. L.,
Cramer William A.,
Howe Christopher J.,
Puthiyaveetil Sujith
Publication year - 2022
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.14340
Subject(s) - thioredoxin , regulator , response regulator , cysteine , thiol , biochemistry , cyanobacteria , microbiology and biotechnology , chemistry , abiotic component , biology , oxidative stress , bacterial protein , enzyme , bacteria , genetics , ecology , gene
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.