Mono- and dimethylating activities and kinetic studies of the ermC 23 S rRNA methyltransferase

C. Denoya, D. Dubnau

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35 Scopus citations


The ermC 23 S rRNA methyltransferase converts a single adenine residue to N6,N6-dimethyladenine, both in vivo and in vitro. The ermC methyltransferase was demonstrated to produce both N6-mono and N6,N6-dimethylated adenine residues in Bacillus subtilis 23 S rRNA during the course of the reaction in vitro. An almost total conversion of monomethylated intermediates into dimethylated products was observed upon completion of the reaction. Data presented here demonstrate that the addition of the two methyl groups to each 23 S rRNA molecule takes place through a monomethylated intermediate and suggest that the enzyme dissociates from the RNA substrate between the two consecutive methylation reactions. The enzyme is able to utilize monomethylated RNA as substrate for the addition of a second methyl group with an efficiency approximately comparable to that obtained when unmethylated RNA was the initial substrate. Initial-rate data and inhibition studies suggest that the ermC methylase reaction involves a sequential mechanism occurring by two consecutive Random Bi Bi reactions.

Original languageEnglish (US)
Pages (from-to)2615-2624
Number of pages10
JournalJournal of Biological Chemistry
Issue number5
StatePublished - 1989

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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