The yfiC gene of E. coli encodes an adenine-N6 methyltransferase that specifically modifies A37 of tRNA1Val(cmo5UAC)

Abstract

Transfer RNA is highly modified. Nucleotide 37 of the anticodon loop is represented by various modified nucleotides. In Escherichia coli, the valine-specific tRNA (cmo5UAC) contains a unique modification, N 6-methyladenosine, at position 37; however, the enzyme responsible for this modification is unknown. Here we demonstrate that the yfiC gene of E. coli encodes an enzyme responsible for the methylation of A37 in tRNA 1Val. Inactivation of yfiC gene abolishes m6A formation in tRNA1Val, while expression of the yfiC gene from a plasmid restores the modification. Additionally, unmodified tRNA 1Val can be methylated by recombinant YfiC protein in vitro. Although the methylation of m6A in tRNA1Val by YfiC has little influence on the cell growth under standard conditions, the yfiC gene confers a growth advantage under conditions of osmotic and oxidative stress. Published by Cold Spring Harbor Laboratory Press. Copyright © 2009 RNA Society.