The “SUN” Family: UTH1, an Ageing Gene, Is Also Involved in the Regulation of Mitochondria Biogenesis in Saccharomyces cerevisiae

• Published in: Archives of biochemistry and biophysics Vol. 375; no. 1; pp. 154 - 160
• Main Authors: Camougrand, N.M., Mouassite, M., Velours, G.M., Guérin, M.G.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2000
• Subjects: Basic Helix-Loop-Helix Transcription Factors; Cardiolipins - metabolism; Cell Division - genetics; Cell Respiration - genetics; Cellular Senescence - physiology; Cytochrome b Group - metabolism; DNA, Mitochondrial - metabolism; Electron Transport Complex IV - metabolism; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Deletion; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; Membrane Proteins; Mitochondria - genetics; Mitochondria - metabolism; Mitochondria - ultrastructure; mitochondria biogenesis; Mitochondrial Proteins; Multigene Family - genetics; Mutagenesis, Site-Directed; Repressor Proteins - genetics; Repressor Proteins - metabolism; S. cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins; SUN family; mitochondria biogenesis; SUN family; S. cerevisiae
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1006/abbi.1999.1655

Since it was shown in previous work that NCA3 (one of the four genes of the SUN family) is involved in mitochondrial protein synthesis regulation, the effect of the other members of this gene family was tested. UTH1 (but not SUN4 or SIM1) was also shown to interfere with mitochondria biogenesis. In Δuth1 cells, cytochromes aa3, c, and b were lowered by 25 and 15%, respectively. In the double-null mutant Δuth1Δnca3, only cytochrome aa3 was lowered by 50% relative to the wild type. However, the ratio of cellular respiration to cytochrome oxidase was greatly enhanced in the double-null mutant. Measurements on whole lysed cells showed that another mitochondrial enzyme, citrate synthase, was also lowered in Δuth1 and Δuth1Δnca3 whereas hexokinase was not. Electron micrographs showed no difference in global mitochondria content in Δuth1Δnca3, but mitochondria appeared less dense to electrons compared to the wild type. Cardiolipin and mtDNA were equivalent in parental and mutant strains. Measurements on isolated mitochondria showed that the cyt aa3/cyt b ratio was also lowered in Δuth1Δnca3, but the control exerted by the oxidase on the respiratory flux was higher. The activity of other mitochondrial complexes versus oxidase was equivalent in mutants compared to the wild type. These results suggest that the protein equipment could be lowered in mitochondria from strains inactivated for UTH1.