Signal transduction by the global regulator RegB is mediated by a redox-active cysteine.
All living organisms alter their physiology in response to changes in oxygen tension. The photosynthetic bacterium uses the RegB-RegA signal transduction cascade to control a wide variety of oxygen-responding processes such as respiration, photosynthesis, carbon fixation and nitrogen fixation. We demonstrate that a highly conserved cysteine has a role in controlling the activity of the sensor kinase, RegB. In vitro studies indicate that exposure of RegB to oxidizing conditions results in the formation of an intermolecular disulfide bond and that disulfide bond formation is metal-dependent, with the metal fulfilling a structural role. Formation of a disulfide bond in vitro is also shown to convert the kinase from an active dimer into an inactive tetramer state. Mutational analysis indicates that a cysteine residue flanked by cationic amino acids is involved in redox sensing in vitro and in vivo. These residues appear to constitute a novel 'redox-box' that is present in sensor kinases from diverse species of bacteria.
Swem
Lee R
LR
Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Kraft
Brian J
BJ
Swem
Danielle L
DL
Setterdahl
Aaron T
AT
Masuda
Shinji
S
Knaff
David B
DB
Zaleski
Jeffrey M
JM
Bauer
Carl E
CE
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D003545:Cysteine; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000378:metabolism*; D011494:Protein Kinases; D016354:Rhodobacter capsulatus / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology*
D001426:Bacterial Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; C091081:RegB protein, Rhodobacter; D011494:Protein Kinases; D003545:Cysteine