Yeast Cells Depleted in Atp14p Fail to Assemble Atp6p within the ATP Synthase and Exhibit Altered Mitochondrial Cristae Morphology

Within the yeast mitochondrial ATP synthase, subunit h is a small nuclear encoded protein belonging to the so-called “peripheral stalk” that connects the enzyme catalytic F1 component to the mitochondrial inner membrane. This study examines the role of subunit h in ATP synthase function and assembly using a regulatable, doxycycline-repressible subunit h gene to overcome the strong instability of the mtDNA previously observed in strains lacking the native subunit h gene. Yeast cells expressing less than 3% of subunit h, but still containing intact mitochondrial genomes, grew poorly on respiratory substrates because of a major impairment of ATP synthesis originating from the ATP synthase, whereas the respiratory chain complexes were not affected. The lack of ATP synthesis in the subunit h-depleted (δh) mitochondria was attributed to defects in the assembly/stability of the ATP synthase. A main feature of δh-mitochondria was a very low content (