Identification of the major tRNAPhe binding domain in the tetrameric structure of cytoplasmic phenylalanyl-tRNA synthetase from baker's yeast

AbstractNative cytoplasmic phenylalanyl-tRNA synthetase from baker's yeast is a tetramer of the α2β2 type. On mild tryptic cleavage it gives rise to a modified ∡2β′2 form that has lost the tRNAPhe binding capacity but is still able to activate phenylalanine. In this paper are presented data concerning peptides released by this limited proteolytic conversion as well as those arising from exhaustive tryptic digestion of the truncated β′ subunit. Each purified peptide was unambiguously assigned to a unique stretch of the β subunit amino acid sequence that was recently determined via gene cloning and DNA sequencing. Together with earlier results from affinity labelling studies the present data show that the Lys 172—Ile 173 bond is the unique target of trypsin under mild conditions and that the N-terminal domain of each β subunit (residues 1–172) contains the major tRNAPhe binding sites

Yeast tRNAMet recognition by methionyl-tRNA synthetase requires determinants from the primary, secondary and tertiary structure: a review

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FPTA 342: Implementación de tecnologías de manejo integrado en predios citrícolas familiares de Salto, con énfasis en plagas y enfermedades cuarentenarias como mosca de la fruta, cancro cítrico y mancha negra.

La propuesta logró acercar las tecnologías disponibles para el manejo integrado de enfermedades y plagas a productores citrícolas familiares de Salto. Asimismo, el grupo de productores participantes del proyecto conoció la problemática del HLB que afecta a la región, a través de capacitaciones y giras al exterior

FPTA 342: Manejo integrado de plagas y enfermedades en productores citrícolas familiares.

En el contexto actual de cuidado del medio ambiente, la inocuidad de los alimentos y la salud de los trabajadores, productores citrícolas de la Sociedad de FomentoRural de Salto avanzan hacia sistemas de producción más sustentables

Importance of structural features for tRNA(Met) identity.

We showed previously that the tRNA tertiary structure makes an important contribution to the identity of yeast tRNA(Met) (Senger B, Aphasizhev R, Walter P, Fasiolo F, 1995, J Mol Biol 249:45-58). To learn more about the role played by the tRNA framework, we analyzed the effect of some phosphodiester cleavages and 2'OH groups in tRNA binding and aminoacylation. The tRNA is inactivated provided the break occurs in the central core region responsible for the tertiary fold or in the anticodon stem/loop region. We also show that, for tRNA(Met) to bind, the anticodon loop, but not the anticodon stem, requires a ribosephosphate backbone. A tertiary mutant of yeast tRNA(Met) involving interactions from the D- and T-loop unique to the initiator species fails to be aminoacylated, but still binds to yeast methionyl-tRNA synthetase. In the presence of 10 mM MgCl2, the mutant transcript has a 3D fold significantly stabilized by about 30 degrees C over a wild-type transcript as deduced from the measure of their T(m) values. The k(cat) defect of the tRNA(Met) mutant may arise from a failure to overcome an increase of the free energetic cost of distorting the more stable tRNA structure and/or a tRNA based MetRS conformational change required for formation of transition state of aminoacylation

The anticodon triplet is not sufficient to confer methionine acceptance to a transfer RNA.

Previous work suggested that the presence of the anticodon CAU alone was enough to confer methionine acceptance to a tRNA. Conversions of Escherichia coli nonmethionine tRNAs to a methionine-accepting species were obtained by substitutions reconstructing the whole methionine anticodon loop together with preservation (or introduction) of the acceptor stem base A73. We show here that the CAU triplet alone is unable to confer methionine acceptance when transplanted into a yeast aspartic tRNA. Both non-anticodon bases of the anticodon loop of yeast tRNA(Met) and A73 are required in addition to CAU for methionine acceptance. The importance of these non-anticodon bases in other CAU-containing tRNA frameworks was also established. These specific non-anticodon base interactions make a substantial thermodynamic contribution to the methionine acceptance of a transfer RNA