A T-stem slip in human mitochondrial tRNALeu(CUN) governs its charging capacity

State Key Laboratory of Molecular Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences 320 Yue Yang Road, Shanghai 200031, People's Republic of China.
Nucleic Acids Research (Impact Factor: 9.11). 02/2005; 33(11):3606-13. DOI: 10.1093/nar/gki677
Source: PubMed


The human mitochondrial tRNALeu(CUN) [hmtRNALeu(CUN)] corresponds to the most abundant codon for leucine in human mitochondrial protein genes. Here, in vitro studies reveal that the U48C substitution in hmtRNALeu(CUN), which corresponds to the pathological T12311C gene mutation, improved the aminoacylation efficiency of hmtRNALeu(CUN). Enzymatic probing suggested a more flexible secondary structure in the wild-type hmtRNALeu(CUN) transcript compared with the U48C mutant. Structural analysis revealed that the flexibility of hmtRNALeu(CUN) facilitates a T-stem slip resulting in two potential tertiary structures. Several rationally designed tRNALeu(CUN) mutants were generated to examine the structural and functional consequences of the T-stem slip. Examination of these hmtRNALeu(CUN) mutants indicated that the T-stem slip governs tRNA accepting activity. These results suggest a novel, self-regulation mechanism of tRNA structure and function.

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Available from: Rui Hao, May 06, 2014
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    • "The increased levels of aminoacylated tRNAHis in mutant cell lines may be due to the instability of the mutant tRNA, where aminoacylation may provide some level of stabilization by compensatory effect (36,37). Alternatively, the mutant tRNAHis improperly charged by cognate amino acid(s) may contribute to the increasing aminoacylation level of tRNAHis (38). A failure to aminoacylate tRNA properly then makes the mutant tRNAHis to be metabolically less stable and more subject to degradation, thereby lowering the level of the tRNA, as in the case of 3243A>G mutation in the tRNALeu(UUR) (25,39). "
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    Nucleic Acids Research 06/2014; 42(12). DOI:10.1093/nar/gku466 · 9.11 Impact Factor
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    • "Our laboratory has investigated the interaction between LeuRS and tRNALeu from various species, including Escherichia coli, Aquifex aeolicus, Giardia lamblia and human (cytosolic and mitochondrial) (6,8–11). The above-mentioned tRNALeu could be purified after overexpression in E. coli or transcribed by T7 RNA polymerase in vitro. "
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    • "The mutation might thus subtly influence the strength of these tertiary interactions. Interestingly, a potentially similar situation has been recently described for tRNALeu(CUN), where two alternative T-stem alignments were found which may influence the same set of tertiary interactions (39). Variations in those same tertiary interactions in cytosolic tRNAs are known to affect the angle between acceptor stem and anticodon stem and have been experimentally shown to affect migration behaviour in non-denaturing gels (40). "
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