Analysis of Mitochondrial Nucleoid Proteins of Yeast Saccharomyces cerevisiae by Means of Two-dimensional Gel Electrophoresis

Abstract

In order to investigate the protein components specific for mitochondrial (mt-) nucleoids, mt-nucleoids isolated from yeast Saccharomyces cerevisiae were analyzed by means of twodimensional (2D-) gel electrophoresis. More than 40 proteins of mt-nucleoids were visualized on a 2D-gel, ranging from acidic to basic pH. Among them, the protein with the most basic property was a 20-kDa protein, Abf2p. Of the 13 proteins, which are abundant in mt-nucleoids, 6 proteins corresponded to those that were separated from mt-nucleoids by means of DNA cellulose chromatography. The 11 proteins among those were discerned to be significantly concentrated in isolated mt-nucleoids when compared with whole mitochondrial protein. The distribution of mt-nucleoid proteins on a 2D-gel was quite different from that of cell nuclear proteins, and the nuclear histones were hardly detected in mt-nucleoid fractions. These results indicated that a specific subset of mitochondrial proteins are associated with mtDNA to form mt-nucleoid structures.