Structural and kinetic analysis of Saccharomyces cerevisiae thioredoxin Trx1: implications for the catalytic mechanism of GSSG reduced by the thioredoxin system.
Thioredoxin (Trx) and glutathione/glutaredoxin (GSH/Grx) systems play the dominant role in cellular redox homeostasis. Recently the Trx system has been shown to be responsible to control the balance of GSH/GSSG once the glutathione reductase system is not available. To decipher the structural basis of electron transfer from the Trx system to GSSG, we solved the crystal structures of oxidized Trx1 and glutathionylated Trx1Cys33Ser mutant at 1.76 and 1.80 A, respectively. Comparative structural analysis revealed a key residue Met35 involved in the Trx-GSSG recognition. Subsequent mutagenesis and kinetic studies proved that Met35Arg mutation could alter the apparent K(m) and V(max) values of the reaction. These findings gave us the structural insights into GSSG reduction catalyzed by the Trx system.
Bao
Rui
R
Institute of Protein Research, Tongji University, Shanghai, PR China.
Zhang
Yaru
Y
Lou
Xiaochu
X
Zhou
Cong-Zhao
CZ
Chen
Yuxing
Y
D000595:Amino Acid Sequence; D003460:Crystallization; D019803:Glutathione Disulfide / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D054464:Peroxiredoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; C103243:TRX1 protein, S cerevisiae; D054464:Peroxiredoxins; D019803:Glutathione Disulfide