Initiation of protein synthesis in Saccharomyces cerevisiae mitochondria without formylation of the initiator tRNA.

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Li Y, Holmes WB, Appling DR, RajBhandary UL

Initiation of protein synthesis in Saccharomyces cerevisiae mitochondria without formylation of the initiator tRNA.

J Bacteriol. 2000 May;182(10):2886-92.

PubMed ID

10781559 [ View in PubMed

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Abstract

Protein synthesis in eukaryotic organelles such as mitochondria and chloroplasts is widely believed to require a formylated initiator methionyl tRNA (fMet-tRNA(fMet)) for initiation. Here we show that initiation of protein synthesis in yeast mitochondria can occur without formylation of the initiator methionyl-tRNA (Met-tRNA(fMet)). The formylation reaction is catalyzed by methionyl-tRNA formyltransferase (MTF) located in mitochondria and uses N(10)-formyltetrahydrofolate (10-formyl-THF) as the formyl donor. We have studied yeast mutants carrying chromosomal disruptions of the genes encoding the mitochondrial C(1)-tetrahydrofolate (C(1)-THF) synthase (MIS1), necessary for synthesis of 10-formyl-THF, and the methionyl-tRNA formyltransferase (open reading frame YBL013W; designated FMT1). A direct analysis of mitochondrial tRNAs using gel electrophoresis systems that can separate fMet-tRNA(fMet), Met-tRNA(fMet), and tRNA(fMet) shows that there is no formylation in vivo of the mitochondrial initiator Met-tRNA in these strains. In contrast, the initiator Met-tRNA is formylated in the respective "wild-type" parental strains. In spite of the absence of fMet-tRNA(fMet), the mutant strains exhibited normal mitochondrial protein synthesis and function, as evidenced by normal growth on nonfermentable carbon sources in rich media and normal frequencies of generation of petite colonies. The only growth phenotype observed was a longer lag time during growth on nonfermentable carbon sources in minimal media for the mis1 deletion strain but not for the fmt1 deletion strain.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Tetrahydrofolic acid	Methionyl-tRNA formyltransferase, mitochondrial	Protein	Humans	Unknown	Cofactor	Details