A 22 kDa protein specific for yeast mitochondrial nucleoids is an unidentified putative ribosomal protein encoded in open reading frame YGL068W

Protoplasma. 2004 Jun;223(2-4):175-82. doi: 10.1007/s00709-004-0040-z. Epub 2004 Jun 22.

Abstract

Mitochondrial-nucleoid (mt-nucleoid) proteins of the yeast Saccharomyces cerevisiae were separated by two-dimensional gel electrophoresis. Analysis of the N-terminal amino acid sequence showed that a 22 kDa protein which is unique in the mt-nucleoid fraction is an unidentified protein encoded in the open reading frame YGL068W and shows a homology with the ribosomal protein L7/L12 of bacteria. We named this protein Mnp1p (for the mitochondrial-nucleoid protein 1). Immunoblotting of each fraction with an anti-Mnp1p antibody during the mt-nucleoid isolation showed that Mnp1p is highly concentrated in the mt-nucleoid fraction. Immunofluorescence microscopy suggested that Mnp1p is localized to mitochondria in vivo, and a significant amount of Mnp1p is associated with the mt-nucleoids. On the other hand, Northern blotting showed that a large amount of large and small mitochondrial ribosomal RNAs was not associated with the mt-nucleoids and remained in the supernatant after the isolation of mt-nucleoids. The null mutation of MNP1 led to a respiratory-deficient phenotype, but the morphology of the mt-nucleoids in the transformants carrying the null mutation was normal. These results suggest that a significant amount of Mnp1p plays a role as a major component of the mt-nucleoids.

MeSH terms

  • Amino Acid Sequence
  • Fungal Proteins / genetics
  • Gene Deletion
  • Mitochondria / chemistry*
  • Mitochondria / metabolism
  • Mitochondrial Proteins / chemistry*
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism
  • Molecular Sequence Data
  • Molecular Weight
  • Open Reading Frames / genetics*
  • Phenotype
  • Protein Transport
  • Ribosomal Proteins / chemistry*
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / metabolism
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism

Substances

  • Fungal Proteins
  • Mitochondrial Proteins
  • Ribosomal Proteins
  • Saccharomyces cerevisiae Proteins
  • ribosomal protein L7-L12