A Riboswitch Regulates Expression of the Coenzyme B12-Independent Methionine Synthase in Mycobacterium tuberculosis: Implications for Differential Methionine Synthase Function in Strains H37Rv and CDC1551

摘要

We observed vitamin B₁₂-mediated growth inhibition of Mycobacterium tuberculosis strain CDC1551. The B₁₂ sensitivity was mapped to a polymorphism in metH, encoding a coenzyme B₁₂-dependent methionine synthase. Vitamin B₁₂-resistant suppressor mutants of CDC1551 containing mutations in a B₁₂ riboswitch upstream of the metE gene, which encodes a B₁₂-independent methionine synthase, were isolated. Expression analysis confirmed that the B₁₂ riboswitch is a transcriptional regulator of metE in M. tuberculosis.