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A SelB/EF-Tu/aIF2γ-like protein from Methanosarcina mazei in the GTP-bound form binds cysteinyl-tRNA(Cys.).
Yanagisawa, Tatsuo; Ishii, Ryohei; Hikida, Yasushi; Fukunaga, Ryuya; Sengoku, Toru; Sekine, Shun-ichi; Yokoyama, Shigeyuki.
Afiliación
  • Yanagisawa T; RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045, Japan.
J Struct Funct Genomics ; 16(1): 25-41, 2015 Mar.
Article en En | MEDLINE | ID: mdl-25618148
The putative translation elongation factor Mbar_A0971 from the methanogenic archaeon Methanosarcina barkeri was proposed to be the pyrrolysine-specific paralogue of EF-Tu ("EF-Pyl"). In the present study, the crystal structures of its homologue from Methanosarcina mazei (MM1309) were determined in the GMPPNP-bound, GDP-bound, and apo forms, by the single-wavelength anomalous dispersion phasing method. The three MM1309 structures are quite similar (r.m.s.d. < 0.1 Å). The three domains, corresponding to domains 1, 2, and 3 of EF-Tu/SelB/aIF2γ, are packed against one another to form a closed architecture. The MM1309 structures resemble those of bacterial/archaeal SelB, bacterial EF-Tu in the GTP-bound form, and archaeal initiation factor aIF2γ, in this order. The GMPPNP and GDP molecules are visible in their co-crystal structures. Isothermal titration calorimetry measurements of MM1309·GTP·Mg(2+), MM1309·GDP·Mg(2+), and MM1309·GMPPNP·Mg(2+) provided dissociation constants of 0.43, 26.2, and 222.2 µM, respectively. Therefore, the affinities of MM1309 for GTP and GDP are similar to those of SelB rather than those of EF-Tu. Furthermore, the switch I and II regions of MM1309 are involved in domain-domain interactions, rather than nucleotide binding. The putative binding pocket for the aminoacyl moiety on MM1309 is too small to accommodate the pyrrolysyl moiety, based on a comparison of the present MM1309 structures with that of the EF-Tu·GMPPNP·aminoacyl-tRNA ternary complex. A hydrolysis protection assay revealed that MM1309 binds cysteinyl (Cys)-tRNA(Cys) and protects the aminoacyl bond from non-enzymatic hydrolysis. Therefore, we propose that MM1309 functions as either a guardian protein that protects the Cys moiety from oxidation or an alternative translation factor for Cys-tRNA(Cys).
Asunto(s)

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: ARN de Transferencia de Cisteína / Methanosarcina / Proteínas Arqueales / Guanosina Trifosfato Tipo de estudio: Prognostic_studies Idioma: En Revista: J Struct Funct Genomics Asunto de la revista: GENETICA Año: 2015 Tipo del documento: Article País de afiliación: Japón Pais de publicación: Países Bajos

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: ARN de Transferencia de Cisteína / Methanosarcina / Proteínas Arqueales / Guanosina Trifosfato Tipo de estudio: Prognostic_studies Idioma: En Revista: J Struct Funct Genomics Asunto de la revista: GENETICA Año: 2015 Tipo del documento: Article País de afiliación: Japón Pais de publicación: Países Bajos