title: Barth syndrome mutations that cause tafazzin complex lability.
abstract: Deficits in mitochondrial function result in many human diseases. The X-linked disease Barth syndrome (BTHS) is caused by mutations in the tafazzin gene TAZ1. Its product, Taz1p, participates in the metabolism of cardiolipin, the signature phospholipid of mitochondria. In this paper, a yeast BTHS mutant tafazzin panel is established, and 18 of the 21 tested BTHS missense mutations cannot functionally replace endogenous tafazzin. Four BTHS mutant tafazzins expressed at low levels are degraded by the intermembrane space AAA (i-AAA) protease, suggesting misfolding of the mutant polypeptides. Paradoxically, each of these mutant tafazzins assembles in normal protein complexes. Furthermore, in the absence of the i-AAA protease, increased expression and assembly of two of the BTHS mutants improve their function. However, the BTHS mutant complexes are extremely unstable and accumulate as insoluble aggregates when disassembled in the absence of the i-AAA protease. Thus, the loss of function for these BTHS mutants results from the inherent instability of the mutant tafazzin complexes.
authors.affiliation: Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA. sclaypo1@jhmi.edu
authors.forename: Steven M
authors.initials: SM
authors.lastname: Claypool
authors.forename: Kevin
authors.initials: K
authors.lastname: Whited
authors.forename: Santi
authors.initials: S
authors.lastname: Srijumnong
authors.forename: Xianlin
authors.initials: X
authors.lastname: Han
authors.forename: Carla M
authors.initials: CM
authors.lastname: Koehler
mesh_terms: D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D056889:Barth Syndrome / Q000235:genetics*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000217:Acyltransferases; C481660:Taz1 protein, S cerevisiae; C486363:tafazzin protein, mouse; C108675:TAFAZZIN protein, human