Protein S-thiolation by Glutathionylspermidine (Gsp): the role of Escherichia coli Gsp synthetASE/amidase in redox regulation.
Certain bacteria synthesize glutathionylspermidine (Gsp), from GSH and spermidine. Escherichia coli Gsp synthetase/amidase (GspSA) catalyzes both the synthesis and hydrolysis of Gsp. Prior to the work reported herein, the physiological role(s) of Gsp or how the two opposing GspSA activities are regulated had not been elucidated. We report that Gsp-modified proteins from E. coli contain mixed disulfides of Gsp and protein thiols, representing a new type of post-translational modification formerly undocumented. The level of these proteins is increased by oxidative stress. We attribute the accumulation of such proteins to the selective inactivation of GspSA amidase activity. X-ray crystallography and a chemical modification study indicated that the catalytic cysteine thiol of the GspSA amidase domain is transiently inactivated by H(2)O(2) oxidation to sulfenic acid, which is stabilized by a very short hydrogen bond with a water molecule. We propose a set of reactions that explains how the levels of Gsp and Gsp S-thiolated proteins are modulated in response to oxidative stress. The hypersensitivities of GspSA and GspSA/glutaredoxin null mutants to H(2)O(2) support the idea that GspSA and glutaredoxin act synergistically to regulate the redox environment of E. coli.
Institute of Biological Chemistry, Facilities for Proteomics Research, Academia Sinica, 128 Academia Road, Section 2, Taipei 11529, Taiwan.
Bing-Yu
BY
Chiang
Tzu-Chieh
TC
Chen
Chien-Hua
CH
Pai
Chi-Chi
CC
Chou
Hsuan-He
HH
Chen
Tzu-Ping
TP
Ko
Wen-Hung
WH
Hsu
Chun-Yang
CY
Chang
Whei-Fen
WF
Wu
Andrew H-J
AH
Wang
Chun-Hung
CH
Lin
D019732:Amide Synthases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D054477:Glutaredoxins / Q000235:genetics / Q000502:physiology; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009154:Mutation / Q000235:genetics; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D013095:Spermidine / Q000031:analogs & derivatives* / Q000378:metabolism
D029968:Escherichia coli Proteins; D054477:Glutaredoxins; D016877:Oxidants; C012333:glutathionylspermidine; D006861:Hydrogen Peroxide; D019732:Amide Synthases; C081536:glutathionylspermidine synthetase; D005978:Glutathione; D013095:Spermidine