title: Isolation and characterization of MOD5, a gene required for isopentenylation of cytoplasmic and mitochondrial tRNAs of Saccharomyces cerevisiae.
abstract: The mod5-1 mutation is a nuclear mutation in Saccharomyces cerevisiae that reduces the biosynthesis of N6-(delta 2-isopentenyl)adenosine in both cytoplasmic and mitochondrial tRNAs to less than 1.5% of wild-type levels. The tRNA modification enzyme, delta 2-isopentenyl pyrophosphate:tRNA isopentenyl transferase, cannot be detected in vitro with extracts from mod5-1 cells. A characterization of the MOD5 gene would help to determine how the same enzyme activity in different cellular compartments can be abolished by a single nuclear mutation. To that end we have cloned the MOD5 gene and shown that it restores delta 2-isopentenyl pyrophosphate:tRNA isopentenyl transferase activity and N6-(delta 2-isopentenyl)adenosine to tRNA in both the mitochondria and the nucleus/cytoplasm compartments of mod5-1 yeast cells. That MOD5 sequences are expressed in Escherichia coli and can complement an N6-(delta 2-isopentenyl)-2-methylthioadenosine-deficient E. coli mutant leads us to conclude that MOD5 is the structural gene for delta 2-isopentenyl pyrophosphate:tRNA isopentenyl transferase.
mesh_terms: D019883:Alkyl and Aryl Transferases; D003593:Cytoplasm / Q000378:metabolism; D004262:DNA Restriction Enzymes; D005796:Genes; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D008928:Mitochondria / Q000378:metabolism; D012343:RNA, Transfer / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014166:Transferases / Q000235:genetics*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D012343:RNA, Transfer; D014166:Transferases; D019883:Alkyl and Aryl Transferases; C068392:MOD5 protein, S cerevisiae; C023197:tRNA isopentenyltransferase; D004262:DNA Restriction Enzymes