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Mitochondrial Respiratory Chain Supercomplexes Are Destabilized in Barth Syndrome Patients

journal contribution
posted on 2006-08-18, 00:00 authored by Matthew McKenzieMatthew McKenzie, M Lazarou, D R Thorburn, M T Ryan
Mutations in the human TAZ gene are associated with Barth Syndrome, an often fatal X-linked disorder that presents with cardiomyopathy and neutropenia. The TAZ gene encodes Tafazzin, a putative phospholipid acyltranferase that is involved in the remodeling of cardiolipin, a phospholipid unique to the inner mitochondrial membrane. It has been shown that the disruption of the Tafazzin gene in yeast (Taz1) affects the assembly and stability of respiratory chain Complex IV and its supercomplex forms. However, the implications of these results for Barth Syndrome are restricted due to the additional presence of Complex I in humans that forms a supercomplex with Complexes III and IV. Here, we investigated the effects of Tafazzin, and hence cardiolipin deficiency in lymphoblasts from patients with Barth Syndrome, using blue-native polyacrylamide gel electrophoresis. Digitonin extraction revealed a more labile Complex I/III2/IV supercomplex in mitochondria from Barth Syndrome cells, with Complex IV dissociating more readily from the supercomplex. The interaction between Complexes I and III was also less stable, with decreased levels of the Complex I/III2supercomplex. Reduction of Complex I holoenzyme levels was observed also in the Barth Syndrome patients, with a corresponding decrease in steady-state subunit levels. We propose that the loss of mature cardiolipin species in Barth Syndrome results in unstable respiratory chain supercomplexes, thereby affecting Complex I biogenesis, respiratory activities and subsequent pathology. © 2006 Elsevier Ltd. All rights reserved.

History

Journal

Journal of Molecular Biology

Volume

361

Issue

3

Pagination

462 - 469

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

0022-2836

Language

eng

Publication classification

CN.1 Other journal article