Identification of the 16S rRNA m5C967 methyltransferase from Escherichia coli

Biochemistry. 1999 Mar 30;38(13):4053-7. doi: 10.1021/bi982364y.


The fmu gene product has been proposed to be an RNA methyltransferase [Koonin, E. V. (1994) Nucleic Acids Res. 22, 2476-2478]. Fmu has been cloned and expressed, and the encoded 47 kDa protein has been purified and characterized. The enzyme catalyzed specific methylation of C967 of unmodified 16S rRNA transcripts. A 16mer stem-loop structure containing C967 (nt 960-975) was also a good substrate for the enzyme in vitro. Methylation of C967 was confirmed by several methods including analysis of RNase T1 digests and nearest-neighbor analysis. Fmu did not catalyze methylation of transcripts of 23S rRNA. E. coli cells that contained kanr-disrupted fmu produced 16S rRNA that could be specifically methylated by Fmu in vitro at C967 but not C1407. Further, fmu disruption did not significantly alter the growth rate of E. coli in rich or minimal media. We propose renaming this ORF "rrmB" and the enzyme "RrmB" for rRNA methyltransferase.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 5-Methylcytosine
  • Cloning, Molecular
  • Cytosine / analogs & derivatives
  • Cytosine / chemistry
  • Endoribonucleases / metabolism
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Gene Deletion
  • Hydroxymethyl and Formyl Transferases / biosynthesis
  • Hydroxymethyl and Formyl Transferases / deficiency
  • Hydroxymethyl and Formyl Transferases / genetics
  • Hydroxymethyl and Formyl Transferases / metabolism
  • Methylation
  • Methyltransferases / isolation & purification*
  • Methyltransferases / metabolism
  • RNA, Ribosomal, 16S / chemistry
  • RNA, Ribosomal, 16S / metabolism*
  • Ribonuclease T1 / metabolism
  • S-Adenosylmethionine / metabolism
  • Single-Strand Specific DNA and RNA Endonucleases / metabolism
  • Substrate Specificity


  • RNA, Ribosomal, 16S
  • 5-Methylcytosine
  • S-Adenosylmethionine
  • Cytosine
  • Methyltransferases
  • m(5)C rRNA methyltransferase
  • Hydroxymethyl and Formyl Transferases
  • methionyl-tRNA formyltransferase
  • Endoribonucleases
  • ribonuclease T(2)
  • Ribonuclease T1
  • Single-Strand Specific DNA and RNA Endonucleases