Résumé : We cloned, expressed, and purified the Escherichia coli YggH protein and show that it catalyzes the S-adenosyl-L-methionine-dependent formation of N(7)-methylguanosine at position 46 (m(7)G46) in tRNA. Additionally, we generated an E. coli strain with a disrupted yggH gene and show that the mutant strain lacks tRNA (m(7)G46) methyltransferase activity.