Thioredoxin 2 from Escherichia coli is not involved in vivo in the recycling process of methionine sulfoxide reductase activities

Thioredoxins (Trx) 1 and 2, and three methionine sulfoxide reductases (Msr) whose activities are Trx-dependent, are expressed in Escherichia coli. A metB(1) trxA mutant was shown to be unable to grow on methionine sulfoxide (Met-O) suggesting that Trx2 is not essential in the Msr-recycling process. In the present study, we have determined the kinetic parameters of the recycling process of the three Msrs by Trx2 and the in vivo expression of Trx2 in a metB(1) trxA mutant. The data demonstrate that the lack of growth of the metB(1) trxA mutant on Met-O is due to low in vivo expression of Trx2 and not to the lower catalytic efficiency of Msrs for Trx2. (C) 2011 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.