Mutations in the substrate binding glycine-rich loop of the mitochondrial processing peptidase-α protein (PMPCA) cause a severe mitochondrial disease.

Abstract

We describe a large Lebanese family with two affected members, a young female proband and her male cousin, who had multisystem involvement including profound global developmental delay, severe hypotonia and weakness, respiratory insufficiency, blindness, and lactic acidemia-findings consistent with an underlying mitochondrial disorder. Whole-exome sequencing was performed on DNA from the proband and both parents. The proband and her cousin carried compound heterozygous mutations in the PMPCA gene that encodes for α-mitochondrial processing peptidase (α-MPP), a protein likely involved in the processing of mitochondrial proteins. The variants were located close to and postulated to affect the substrate binding glycine-rich loop of the α-MPP protein. Functional assays including immunofluorescence and western blot analysis on patient's fibroblasts revealed that these variants reduced α-MPP levels and impaired frataxin production and processing. We further determined that those defects could be rescued through the expression of exogenous wild-type PMPCA cDNA. Our findings link defective α-MPP protein to a severe mitochondrial disease.

• Authors: Mugdha Joshi, Irina Anselm, Jiahai Shi, Tejus A Bale, Meghan Towne, Klaus Schmitz-Abe, Laura Crowley, Felix C Giani, Shideh Kazerounian, Kyriacos Markianos, Hart G Lidov, Rebecca Folkerth, Vijay G Sankaran, Pankaj B Agrawal
• Journal: Cold Spring Harbor molecular case studies (Cold Spring Harb Mol Case Stud) Vol. 2 Issue 3 Pg. a000786 (May 2016) ISSN: 2373-2873 [Print] United States
• PMID: 27148589 (Publication Type: Journal Article)