Impact of single amino acid mutations in the rhomboid protease Pcp1p on Pcp1p catalytic activity, cellular respiration, mitochondrial morphology, and mitochondrial DNA maintenance
Both, Andries Pieter
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Pcp1p is a rhomboid protease in the inner mitochondrial membrane of S. cerevisiae that processes Mgm1p, a protein required for mitochondrial fusion. In this study, five previously generated pcp1 mutant strains were analyzed for mitochondrial respiration, genome maintenance, and tubularization. We found that mutations that introduced a charged residue into Pcp1p resulted in a higher degree of respiratory deficiency, mtDNA loss, mitochondrial fragmentation, and possible mitochondrial membrane potential loss. Furthermore, these mutant phenotypes paralleled an increase in an aberrant form of Mgm1p that accumulates in the absence of wild type Pcp1p. This raises questions about the biogenesis of aberrant Mgm1p and its involvement in disrupting normal mitochondrial fusion. The findings outlined herein will help to establish a cascade of events that lead from loss of proper Mgm1p cleavage to associated cellular defects. Complete understanding of these connections will be valuable in establishing a similar cascade in the human disease ADOA.