A RARE TRANSFER RNA-ARG(CCU) THAT REGULATES TY1 ELEMENT RIBOSOMAL FRAMESHIFTING IS ESSENTIAL FOR TY1 RETROTRANSPOSITION IN SACCHAROMYCES-CEREVISIAE

作者：KAWAKAMI K^*; PANDE S; FAIOLA B; MOORE DP; BOEKE JD; FARABAUGH PJ; STRATHERN JN; NAKAMURA Y; GARFINKEL DJ

来源：Genetics, 1993, 135(2): 309-320.

Translation of the yeast retrotransposon Tyl TYA1(gag)-TYB1(pol) gene occurs by a + 1 ribosomal frameshifting event at the sequence CUU AGG C. Because overexpression of a low abundance tRNA-Arg(CCU) encoded by the HSX1 gene resulted in a reduction in Ty1 frameshifting, it was suggested that a translational pause at the AGG-Arg codon is required for optimum frameshifting. The present work shows that the absence of tRNA-Arg(CCU) affects Ty1 transposition, translational frameshifting, and accumulation of mature TYB1 proteins. Transposition of genetically tagged Ty1 elements decreases at least 50-fold and translational frameshifting increases 3-17-fold in cells lacking tRNA-Arg(CCU). Accumulation of Ty1-integrase and Ty1-reverse transcriptase/ribonuclease H is defective in an hsx1 mutant. The defect in Ty1 transposition is complemented by the wild-type HSX1 gene or a mutant tRNA-Arg(UCU) gene containing a C for T substitution in the first position of the anticodon. Overexpression of TYA 1 stimulates Ty 1 transposition 50-fold above wild-type levels when the level of transposition is compared in isogenic hsx1 and HSX1 strains. Thus, the HSX1 gene determines the ratio of the TYA 1 to TYA 1 -TYB 1 precursors required for protein processing or stability, and keeps expression of TYB1 a rate-limiting step in the retrotransposition cycle.

• 出版日期1993-10
• 单位河北医科大学