title: Crystallographic capture of a radical S-adenosylmethionine enzyme in the act of modifying tRNA.
abstract: RlmN is a dual-specificity RNA methylase that modifies C2 of adenosine 2503 (A2503) in 23S rRNA and C2 of adenosine 37 (A37) in several Escherichia coli transfer RNAs (tRNAs). A related methylase, Cfr, modifies C8 of A2503 via a similar mechanism, conferring resistance to multiple classes of antibiotics. Here, we report the x-ray structure of a key intermediate in the RlmN reaction, in which a Cys(118)→Ala variant of the protein is cross-linked to a tRNA(Glu)substrate through the terminal methylene carbon of a formerly methylcysteinyl residue and C2 of A37. RlmN contacts the entire length of tRNA(Glu), accessing A37 by using an induced-fit strategy that completely unfolds the tRNA anticodon stem-loop, which is likely critical for recognition of both tRNA and ribosomal RNA substrates.
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Erica L
authors.initials: EL
authors.lastname: Schwalm
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Tyler L
authors.initials: TL
authors.lastname: Grove
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA. Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA. Howard Hughes Medical Institute, Pennsylvania State University, University Park, PA 16802, USA. squire@psu.edu akb20@psu.edu.
authors.forename: Squire J
authors.initials: SJ
authors.lastname: Booker
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA. Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA. squire@psu.edu akb20@psu.edu.
authors.forename: Amie K
authors.initials: AK
authors.lastname: Boal
mesh_terms: D000241:Adenosine / Q000737:chemistry; D000409:Alanine / Q000737:chemistry / Q000235:genetics; D019943:Amino Acid Substitution; D000926:Anticodon / Q000737:chemistry; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure*; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure*; D009690:Nucleic Acid Conformation; D017434:Protein Structure, Tertiary; D012329:RNA, Bacterial / Q000737:chemistry*; D012352:RNA, Transfer, Glu / Q000737:chemistry* / Q000648:ultrastructure*; D012436:S-Adenosylmethionine / Q000737:chemistry
chemical_list: D000926:Anticodon; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D012352:RNA, Transfer, Glu; D012436:S-Adenosylmethionine; D008780:Methyltransferases; C558134:RlmN protein, E coli; D000241:Adenosine; D003545:Cysteine; D000409:Alanine