FIG. 3.

P1-encoded tRNAs and codons presumably recognized by them. The identity determinants of tRNAs are marked by asterisks. The putative modification of tRNA3 by lysinylation at the 2 position of cytosine alters the recognition specificity of the anticodon. The bar graphs compare the usage frequencies of codons recognized by P1 tRNAs in protein-coding genes of P1 (black bars) and E. coli K-12 (grey bars) per 1,000 codons. The usage frequency of a particular codon in P1 is its relative abundance among codons in genes that encode proteins. The usage frequency of a particular codon in E. coli K-12 is according to the March 2004 edition of the Codon Usage Database found at its website (http://www.kazusa.or.jp/codon/).