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S-Adenosyl-S-carboxymethyl-L-homocysteine: a novel cofactor found in the putative tRNA-modifying enzyme CmoA.
Byrne, Robert T; Whelan, Fiona; Aller, Pierre; Bird, Louise E; Dowle, Adam; Lobley, Carina M C; Reddivari, Yamini; Nettleship, Joanne E; Owens, Raymond J; Antson, Alfred A; Waterman, David G.
Afiliación
  • Byrne RT; York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington YO10 5DD, England.
Acta Crystallogr D Biol Crystallogr ; 69(Pt 6): 1090-8, 2013 Jun.
Article en En | MEDLINE | ID: mdl-23695253
Uridine at position 34 of bacterial transfer RNAs is commonly modified to uridine-5-oxyacetic acid (cmo(5)U) to increase the decoding capacity. The protein CmoA is involved in the formation of cmo(5)U and was annotated as an S-adenosyl-L-methionine-dependent (SAM-dependent) methyltransferase on the basis of its sequence homology to other SAM-containing enzymes. However, both the crystal structure of Escherichia coli CmoA at 1.73 Å resolution and mass spectrometry demonstrate that it contains a novel cofactor, S-adenosyl-S-carboxymethyl-L-homocysteine (SCM-SAH), in which the donor methyl group is substituted by a carboxymethyl group. The carboxyl moiety forms a salt-bridge interaction with Arg199 that is conserved in a large group of CmoA-related proteins but is not conserved in other SAM-containing enzymes. This raises the possibility that a number of enzymes that have previously been annotated as SAM-dependent are in fact SCM-SAH-dependent. Indeed, inspection of electron density for one such enzyme with known X-ray structure, PDB entry 1im8, suggests that the active site contains SCM-SAH and not SAM.
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Texto completo: 1 Colección: 01-internacional Banco de datos: MEDLINE Asunto principal: S-Adenosilhomocisteína / ARN de Transferencia / Transferasas del Grupo 1-Carbono / Proteínas de Escherichia coli / Escherichia coli Idioma: En Revista: Acta Crystallogr D Biol Crystallogr Año: 2013 Tipo del documento: Article País de afiliación: Reino Unido

Texto completo: 1 Colección: 01-internacional Banco de datos: MEDLINE Asunto principal: S-Adenosilhomocisteína / ARN de Transferencia / Transferasas del Grupo 1-Carbono / Proteínas de Escherichia coli / Escherichia coli Idioma: En Revista: Acta Crystallogr D Biol Crystallogr Año: 2013 Tipo del documento: Article País de afiliación: Reino Unido