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.
Nagahara
Noriyuki
N
Department of Environmental Medicine, Nippon Medical School, 1-1-5 Sendagi, Tokyo 113-8602, Japan. noriyuki@nms.ac.jp
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