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Synthesis and investigation of the 5-formylcytidine modified, anticodon stem and loop of the human mitochondrial tRNAMet.

ABSTRACT: Human mitochondrial methionine transfer RNA (hmtRNA(Met)(CAU)) has a unique post-transcriptional modification, 5-formylcytidine, at the wobble position-34 (f(5)C(34)). The role of this modification in (hmtRNA(Met)(CAU)) for the decoding of AUA, as well as AUG, in both the peptidyl- and aminoacyl-sites of the ribosome in either chain initiation or chain elongation is still unknown. We report the first synthesis and analyses of the tRNA's anticodon stem and loop domain containing the 5-formylcytidine modification. The modification contributes to the tRNA's anticodon domain structure, thermodynamic properties and its ability to bind codons AUA and AUG in translational initiation and elongation.

SUBMITTER: Lusic H

PROVIDER: S-EPMC2582600 | biostudies-literature | 2008 Nov

REPOSITORIES: biostudies-literature

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Synthesis and investigation of the 5-formylcytidine modified, anticodon stem and loop of the human mitochondrial tRNAMet.

Lusic Hrvoje H Gustilo Estella M EM Vendeix Franck A P FA Kaiser Rob R Delaney Michael O MO Graham William D WD Moye Virginia A VA Cantara William A WA Agris Paul F PF Deiters Alexander A

Nucleic acids research 20081016 20

Human mitochondrial methionine transfer RNA (hmtRNA(Met)(CAU)) has a unique post-transcriptional modification, 5-formylcytidine, at the wobble position-34 (f(5)C(34)). The role of this modification in (hmtRNA(Met)(CAU)) for the decoding of AUA, as well as AUG, in both the peptidyl- and aminoacyl-sites of the ribosome in either chain initiation or chain elongation is still unknown. We report the first synthesis and analyses of the tRNA's anticodon stem and loop domain containing the 5-formylcytid ...[more]

PMID: 18927116

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The human mitochondrial tRNAMet: structure/function relationship of a unique modification in the decoding of unconventional codons.

Project description:Human mitochondrial mRNAs utilize the universal AUG and the unconventional isoleucine AUA codons for methionine. In contrast to translation in the cytoplasm, human mitochondria use one tRNA, hmtRNA(Met)(CAU), to read AUG and AUA codons at both the peptidyl- (P-), and aminoacyl- (A-) sites of the ribosome. The hmtRNA(Met)(CAU) has a unique post-transcriptional modification, 5-formylcytidine, at the wobble position 34 (f(5)C(34)), and a cytidine substituting for the invariant uridine at position 33 of the canonical U-turn in tRNAs. The structure of the tRNA anticodon stem and loop domain (hmtASL(Met)(CAU)), determined by NMR restrained molecular modeling, revealed how the f(5)C(34) modification facilitates the decoding of AUA at the P- and the A-sites. The f(5)C(34) defined a reduced conformational space for the nucleoside, in what appears to have restricted the conformational dynamics of the anticodon bases of the modified hmtASL(Met)(CAU). The hmtASL(Met)(CAU) exhibited a C-turn conformation that has some characteristics of the U-turn motif. Codon binding studies with both Escherichia coli and bovine mitochondrial ribosomes revealed that the f(5)C(34) facilitates AUA binding in the A-site and suggested that the modification favorably alters the ASL binding kinetics. Mitochondrial translation by many organisms, including humans, sometimes initiates with the universal isoleucine codons AUU and AUC. The f(5)C(34) enabled P-site codon binding to these normally isoleucine codons. Thus, the physicochemical properties of this one modification, f(5)C(34), expand codon recognition from the traditional AUG to the non-traditional, synonymous codons AUU and AUC as well as AUA, in the reassignment of universal codons in the mitochondria.

| S-EPMC3662834 | biostudies-literature

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