Phylogenetic relationships among 16S rRNA methyltransferases. Twenty amino acid sequences of known 16S rRNA methyltransferases were compared in CLUSTALW, and the results were illustrated using the TreeViewX program, version 0.5.0 for Macintosh OS X. GenBank or EMBL accession numbers associated with each gene are as follows: RmtA, AB120321; RmtB, AB117036; ArmA, AF550415; RmtC, AB194779; RmtD, DQ914960; RmtE, GU201947; NpmA, AB261016; FmrO, D13171; GrmO, AY524043; Grm, M55521; Sgm, A45282; GrmA, AY524043; Kmr, AB164642; Kan, AJ414669; NbrB, AF038408; KgmB, AAB20100; KamA (FmrT), D13170; KamC, AAA26499; KamB, CAF33037; and Amr, AAB08.