Structural basis for methyl transfer by a radical SAM enzyme

Amie K. Boal, Tyler L. Grove, Monica I. McLaughlin, Neela H. Yennawar, Squire J. Booker, Amy C. Rosenzweig

Research output: Contribution to journalArticlepeer-review

126 Scopus citations

Abstract

The radical S-adenosyl-L-methionine (SAM) enzymes RlmN and Cfr methylate 23S ribosomal RNA, modifying the C2 or C8 position of adenosine 2503. The methyl groups are installed by a two-step sequence involving initial methylation of a conserved Cys residue (RlmN Cys355) by SAM. Methyl transfer to the substrate requires reductive cleavage of a second equivalent of SAM. Crystal structures of RlmN and RlmN with SAM show that a single molecule of SAM coordinates the [4Fe-4S] cluster. Residue Cys355 is S-methylated and located proximal to the SAM methyl group, suggesting the SAM that is involved in the initial methyl transfer binds at the same site. Thus, RlmN accomplishes its complex reaction with structural economy, harnessing the two most important reactivities of SAM within a single site.

Original languageEnglish (US)
Pages (from-to)1089-1092
Number of pages4
JournalScience
Volume332
Issue number6033
DOIs
StatePublished - May 27 2011

ASJC Scopus subject areas

  • General

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