Le, Dung TienTarrago, LionelWatanabe, YasukoKaya, AlaattinLee, Byung CheonTran, UyenNishiyama, RieFomenko, Dmitri E.Gladyshev, Vadim N.Tran, Lam-Son Phan2014-02-132013Le, Dung Tien, Lionel Tarrago, Yasuko Watanabe, Alaattin Kaya, Byung Cheon Lee, Uyen Tran, Rie Nishiyama, Dmitri E. Fomenko, Vadim N. Gladyshev, and Lam-Son Phan Tran. 2013. “Diversity of Plant Methionine Sulfoxide Reductases B and Evolution of a Form Specific for Free Methionine Sulfoxide.” PLoS ONE 8 (6): e65637. doi:10.1371/journal.pone.0065637. http://dx.doi.org/10.1371/journal.pone.0065637.1932-6203http://nrs.harvard.edu/urn-3:HUL.InstRepos:11708683Methionine can be reversibly oxidized to methionine sulfoxide (MetO) under physiological conditions. Organisms evolved two distinct methionine sulfoxide reductase families (MSRA & MSRB) to repair oxidized methionine residues. We found that 5 MSRB genes exist in the soybean genome, including GmMSRB1 and two segmentally duplicated gene pairs (GmMSRB2 and GmMSRB5, GmMSRB3 and GmMSRB4). GmMSRB2 and GmMSRB4 proteins showed MSRB activity toward protein-based MetO with either DTT or thioredoxin (TRX) as reductants, whereas GmMSRB1 was active only with DTT. GmMSRB2 had a typical MSRB mechanism with Cys121 and Cys 68 as catalytic and resolving residues, respectively. Surprisingly, this enzyme also possessed the MSRB activity toward free Met-R-O with kinetic parameters similar to those reported for fRMSR from Escherichia coli, an enzyme specific for free Met-R-O. Overexpression of GmMSRB2 or GmMSRB4 in the yeast cytosol supported the growth of the triple MSRA/MSRB/fRMSR (Δ3MSRs) mutant on MetO and protected cells against H2O2-induced stress. Taken together, our data reveal an unexpected diversity of MSRBs in plants and indicate that, in contrast to mammals that cannot reduce free Met-R-O and microorganisms that use fRMSR for this purpose, plants evolved MSRBs for the reduction of both free and protein-based MetO.en-USAgricultureAgricultural BiotechnologyGenetically Modified OrganismsBiologyBiochemistryEnzymesEnzyme ClassesOxidoreductasesEnzyme KineticsEnzyme MetabolismPlant BiochemistryProteinsBiotechnologyBiocatalysisPlant BiotechnologyGenomicsPlant ScienceProteomicsProtein EngineeringJournal Article2014-02-1310.1371/journal.pone.0065637