A novel mercaptopyruvate sulfurtransferase thioredoxin-dependent redox-sensing molecular switch: a mechanism for the maintenance of cellular redox equilibrium.
An intermolecular disulfide bond serves as a thioredoxin-dependent redox-sensing switch for the regulation of the enzymatic activity of 3-mercaptopyruvate sulfurtransferase (MST, EC.2.8.1.2). A cysteine residue on the surface of each subunit was oxidized to form an intersubunit disulfide bond so as to decrease MST activity, and thioredoxin-specific conversion of a dimer to a monomer increased MST activity. Further, a low redox potential sulfenate was reversibly formed at a catalytic site cysteine so as to inhibit MST, and thioredoxin-dependent reduction of the sulfenate restored the MST activity. Concludingly, MST partly contributes to the maintenance of cellular redox homeostasis via exerting control over cysteine catabolism.
Department of Environmental Medicine, Nippon Medical School, 1-1-5 Sendagi, Tokyo 113-8602, Japan. noriyuki@nms.ac.jp
Noriyuki
N
Nagahara
D000818:Animals; D003545:Cysteine / Q000737:chemistry; D019143:Evolution, Molecular; D006801:Humans; D008954:Models, Biological; D010084:Oxidation-Reduction; D016415:Sequence Alignment; D013466:Sulfurtransferases / Q000737:chemistry* / Q000145:classification / Q000187:drug effects; D013879:Thioredoxins / Q000494:pharmacology*
D013879:Thioredoxins; D013466:Sulfurtransferases; C021550:3-mercaptopyruvate sulphurtransferase; D003545:Cysteine