Identification of the rrmA Gene Encoding the 23S rRNA m1G745 Methyltransferase in Escherichia coli and Characterization of an m1G745-Deficient Mutant

摘要

An Escherichia coli mutant lacking the modified nucleotide m1G in rRNA has previously been isolated (G. R. Bj?rk and L. A. Isaksson, J. Mol. Biol. 51:83–100, 1970). In this study, we localize the position of the m1G to nucleotide 745 in 23S rRNA and characterize a mutant deficient in this modification. This mutant shows a 40% decreased growth rate in rich media, a drastic reduction in loosely coupled ribosomes, a 20% decreased polypeptide chain elongation rate, and increased resistance to the ribosome binding antibiotic viomycin. TherrmA gene encoding 23S rRNA m1G745 methyltransferase was mapped to bp 1904000 on the E. colichromosome and identified to be identical to the previously sequenced gene yebH.