Monomeric NADH-Oxidizing Methylenetetrahydrofolate Reductases from Mycobacterium smegmatis Lack Flavin Coenzyme.

ABSTRACT: 5,10-Methylenetetrahydrofolate reductase (MetF/MTHFR) is an essential enzyme in one-carbon metabolism for de novo biosynthesis of methionine. Our in vivo and in vitro analyses of MSMEG_6664/MSMEI_6484, annotated as putative MTHFR in Mycobacterium smegmatis, failed to reveal their function as MTHFRs. However, we identified two hypothetical proteins, MSMEG_6596 and MSMEG_6649, as noncanonical MTHFRs in the bacterium. MTHFRs are known to be oligomeric flavoproteins. Both MSMEG_6596 and MSMEG_6649 are monomeric proteins and lack flavin coenzymes. In vitro, the catalytic efficiency (k_cat/K_m ) of MSMEG_6596 (MTHFR1) for 5,10-CH₂-THF and NADH was ∼13.5- and 15.3-fold higher than that of MSMEG_6649 (MTHFR2). Thus, MS

SUBMITTER: Sah S 

PROVIDER: S-EPMC7253612 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature