Protoplasma

, Volume 219, Issue 1, pp 51–58

Identification of the YMN-1 antigen protein and biochemical analyses of protein components in the mitochondrial nucleoid fraction of the yeast Saccharomyces cerevisiae

Authors

  • H. Sato
    • Department of Physics, Biology and Informatics, Faculty of Science, Yamaguchi University, Yamaguchi
  • A. Tachifuji
    • Department of Physics, Biology and Informatics, Faculty of Science, Yamaguchi University, Yamaguchi
  • M. Tamura
    • Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, Tennessee
  • I. Miyakawa
    • Department of Physics, Biology and Informatics, Faculty of Science, Yamaguchi University, Yamaguchi

DOI: 10.1007/s007090200005

Cite this article as:
Sato, H., Tachifuji, A., Tamura, M. et al. Protoplasma (2002) 219: 51. doi:10.1007/s007090200005

Summary.

We analyzed the protein components contained in the mitochondrial nucleoid (mt-nucleoid) fraction of the yeast Saccharomyces cerevisiae. Immunoblotting with anti-Abf2p antibody demonstrated the association of Abf2p, a major mitochondrial DNA-binding protein, with the mt-nucleoids. In contrast, porin and cytochrome c oxidase subunit III (CoxIIIp) were not detected by immunoblotting in the mt-nucleoid fraction. The YMN-1 monoclonal antibody recognized a 48 kDa protein of the mt-nucleoid fraction. The N-terminal amino acid sequence of the protein and immunological evidence showed that the YMN-1 monoclonal antibody recognizes dihydrolipoyl transsuccinylase (KE2), which is one of the constituents of the α-ketoglutarate dehydrogenase complex (KGDC). α-Ketoglutarate dehydrogenase (KE1) and dihydrolipoyl dehydrogenase (E3), which are other subunits of KGDC, were also detected in the mt-nucleoid fraction. An enzyme assay of the mt-nucleoid fraction showed that cytochrome c oxidase and fumarase activity were barely detected in the fraction, but the specific activity of KGDC in the mt-nucleoid fraction was relatively high and was approximately 60% of the specific activity in the mitochondrial fraction. Three components of KGDC were detected in the DNA-binding protein fractions after DNA-cellulose column chromatography of mt-nucleoid proteins. These results suggested that a part of KGDC in the mitochondrial matrix is associated with mt-nucleoids in vivo.

Keywords: Yeast; Saccharomyces cerevisiae; Mitochondria; Mitochondrial nucleoid; α-Ketoglutarate dehydrogenase complex.

Copyright information

© Springer-Verlag Wien 2002