Translation initiation of HTS1 in yeast
| Autor: | Yi-Yi Kuo, 郭亦亦 |
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| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 In yeast, there are two sets of aminoacyl-tRNA synthetases, one localized in the cytoplasm and the other in the mitochondria. Most of the mitochondrial tRNA synthetases are encoded by nuclear genes distinct from those encoding their cytoplasmic counterparts. However, some mitochondrial tRNA synthetases are encoded by the same genes that code for their cytoplasmic homologues. For example, the cytoplasmic and mitochondrial histidyl-tRNA synthetases of Saccharomyces cerevisiae (ScHisRS) are encoded by the same nuclear gene, HTS1, through alternative initiation of translation from two in-frame AUG codons. The gene specifies two messages, the longer one with two 5’-end in-frame AUGs and the short one with only the second AUG. In this study, we showed that the HisRS genes of Schizosaccharomyces pombe、Candida albicans and Aspergillus fumigatus have only one gene that also contain two in-frame AUG initiation codons. The mitochodrial and cytosolic forms are translated from the first and second AUG initiation codons, respectively. Besides, we found that ScHisRS had a lysine-rich N-terminal polypeptide extension of 34 residues, which was absent from its E. coli counterpart. Attachment of this appended domain to E. coli glutaminyl-tRNA synthetase did not enhance the enzyme’s tRNA-binding and aminoacylation activity toward yeast tRNAs. Deletion of the appended domain of ScHisRS had little effect on the enzyme’s complementation activity in vivo. These results suggest that the appended domain is not essential for the cytoplasmic and mitochondrial functions of ScHisRS in vivo. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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