MAS5, a yeast homolog of DnaJ involved in mitochondrial protein import.
The nuclear mas5 mutation causes temperature-sensitive growth and defects in mitochondrial protein import at the nonpermissive temperature in the yeast Saccharomyces cerevisiae. The MAS5 gene was isolated by complementation of the mutant phenotypes, and integrative transformation demonstrated that the complementing fragment encoded the authentic MAS5 gene. The deduced protein sequence of the cloned gene revealed a polypeptide of 410 amino acids which is homologous to Escherichia coli DnaJ and the yeast DnaJ log SCJ1. Northern (RNA blot) analysis revealed that MAS5 is a heat shock gene whose expression increases moderately at elevated temperatures. Cells with a deletion mutation in MAS5 grew slowly at 23 degrees C and were inviable at 37 degrees C, demonstrating that MAS5 is essential for growth at increased temperatures. The deletion mutant also displayed a modest import defect at 23 degrees C and a substantial import defect at 37 degrees C. These results indicate a role for a DnaJ cognate protein in mitochondrial protein import.
Atencio
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DP
Department of Biology, University of California, San Diego, La Jolla 92093.
Yaffe
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MP
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D004271:DNA, Fungal; D029968:Escherichia coli Proteins; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005800:Genes, Fungal; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013696:Temperature
D001426:Bacterial Proteins; D004271:DNA, Fungal; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; C070319:YDJ1 protein, S cerevisiae