title: The efficiency of mitochondrial electron transport chain is increased in the long-lived mrg19 Saccharomyces cerevisiae.
abstract: Integrity of mitochondrial functionality is a key determinant of longevity in several organisms. In particular, reduced mitochondrial ROS (mtROS) production leading to decreased mtDNA damage is believed to be a crucial aspect of longevity. The generation of low mtROS was thought to be due to low mitochondrial oxygen consumption. However, recent studies have shown that higher mitochondrial oxygen consumption could still result in low mtROS and contribute to longevity. This increased mitochondrial efficiency (i.e. low mtROS generated despite high oxygen consumption) was explained as a result of mitochondrial biogenesis, which provides more entry points for the electrons to the electron transport chain (ETC), thereby resulting in low mtROS production. In this study, we provide evidence for the existence of an alternative pathway to explain the observed higher mitochondrial efficiency in the long-lived mrg19 mutant of Saccharomyces cerevisiae. Although we observe similar amounts of mitochondria in mrg19 and wild-type (wt) yeast, we find that mrg19 mitochondria have higher expression of ETC components per mitochondria in comparison with the wt. These findings demonstrate that more efficient mitochondria because of increased ETC per mitochondria can also produce less mtROS. Taken together, our findings provide evidence for an alternative explanation for the involvement of higher mitochondrial activity in prolonging lifespan. We anticipate that similar mechanisms might also exist in eukaryotes including human.
authors.affiliation: Department of Biotechnology, National Institute of Pharmaceutical Education and Research, S. A. S. Nagar, Punjab, India.
authors.forename: Nitish
authors.initials: N
authors.lastname: Mittal
authors.forename: M Madan
authors.initials: MM
authors.lastname: Babu
authors.forename: Nilanjan
authors.initials: N
authors.lastname: Roy
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000975:Antioxidants / Q000378:metabolism; D004579:Electron Transport; D015966:Gene Expression Regulation, Fungal; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism*; D010101:Oxygen Consumption; D017382:Reactive Oxygen Species / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000975:Antioxidants; C497794:MRG19 protein, S cerevisiae; D017382:Reactive Oxygen Species; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate