Essential Role of the HMG Domain in the Function of Yeast Mitochondrial Histone HM: Functional Complementation of HM by the Nuclear Nonhistone Protein NHP6A

• Published in: Proceedings of the National Academy of Sciences - PNAS 1993-06, Vol.90 (12), p.5598-5602
• Main Authors: Kao, Ling-Rong, Megraw, Timothy L., Chae, Chi-Bom
• Format: Article
• Language: English
• Subjects: Amino acids; Analytical, structural and metabolic biochemistry; Animals; ATP-Binding Cassette Transporters; Base Sequence; Biochemistry; Biological and medical sciences; Carrier Proteins - biosynthesis; Carrier Proteins - genetics; Cell Nucleus - metabolism; DNA; DNA, Superhelical - metabolism; DNA-Binding Proteins - metabolism; Escherichia coli - genetics; Escherichia coli Proteins; Fundamental and applied biological sciences. Psychology; Gels; Genes; Genetic Complementation Test; Genomes; High Mobility Group Proteins - genetics; High Mobility Group Proteins - metabolism; Histones; Holoproteins; Maltose - metabolism; Maltose-Binding Proteins; Mitochondria; Mitochondria - metabolism; Molecular Sequence Data; Monosaccharide Transport Proteins; Mutagenesis, Site-Directed; Mutation; Nuclear proteins; Oligodeoxyribonucleotides; Oxygen Consumption; Plasmids; Promoter Regions, Genetic; Proteins; Rats; Recombinant Fusion Proteins - biosynthesis; Respiration; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Sequence Deletion; Thyroglobulin - genetics; Yeast; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.90.12.5598

The yeast mitochondrial histone protein HM is required for maintenance of the mitochondrial genome, and disruption of the gene encoding HM (HIM1/ABF2) results in formation of a respiration-deficient petite mutant phenotype. HM contains two homologous regions, which share sequence similarity with the eukaryotic nuclear nonhistone protein, HMG-1. Experiments with various deletion mutants of HM show that a single HMG domain of HM is functional and can restore respiration competency to cells that lack HM protein (him1 mutant cells). The gene encoding the putative yeast nuclear HMG-1 homolog, the NHP6A protein, can functionally complement the him1 mutation. These results suggest that the HMG domain is the basic unit for the function of HM in mitochondria and that the function of HMG-1 proteins in the nucleus and HM in the mitochondrion may be equivalent.