**Human Mitochondrial Pathologies of the Respiratory Chain and ATP Synthase: Contributions from Studies of** *Saccharomyces cerevisiae*

#### **Leticia V. R. Franco 1,2, \* , Luca Bremner <sup>1</sup> and Mario H. Barros 2**


Received: 27 October 2020; Accepted: 19 November 2020; Published: 23 November 2020

**Abstract:** The ease with which the unicellular yeast *Saccharomyces cerevisiae* can be manipulated genetically and biochemically has established this organism as a good model for the study of human mitochondrial diseases. The combined use of biochemical and molecular genetic tools has been instrumental in elucidating the functions of numerous yeast nuclear gene products with human homologs that affect a large number of metabolic and biological processes, including those housed in mitochondria. These include structural and catalytic subunits of enzymes and protein factors that impinge on the biogenesis of the respiratory chain. This article will review what is currently known about the genetics and clinical phenotypes of mitochondrial diseases of the respiratory chain and ATP synthase, with special emphasis on the contribution of information gained from *pet* mutants with mutations in nuclear genes that impair mitochondrial respiration. Our intent is to provide the yeast mitochondrial specialist with basic knowledge of human mitochondrial pathologies and the human specialist with information on how genes that directly and indirectly affect respiration were identified and characterized in yeast.

**Keywords:** mitochondrial diseases; respiratory chain; yeast; *Saccharomyces cerevisiae*; *pet* mutants
