Only one splice variant of the human TAZ gene encodes a functional protein with a role in cardiolipin metabolism.
Barth syndrome (BTHS) is an X-linked recessive disorder caused by mutations in the TAZ gene and is characterized by cardiomyopathy, short stature, neutropenia, and 3-methylglutaconic aciduria. Recently it was found that BTHS patients exhibit a profound cardiolipin deficiency although the biosynthetic capacity to synthesize this lipid from its precursor phosphatidylglycerol is entirely normal. Like BTHS patients, a Saccharomyces cerevisiae strain, in which the yeast orthologue of the human TAZ gene has been disrupted, exhibits an abnormal cardiolipin profile as determined by tandem mass spectrometry. Additionally, this yeast strain grows poorly on non-fermentable carbon sources. We have used both properties of this yeast disruptant as a read-out system to test the physiological functionality of each of 12 different splice variants that have been reported for the human TAZ gene. Our results demonstrate that only the splice variant lacking exon 5 was able to complement the retarded growth of the yeast disruptant on selective plates and restore the cardiolipin profile to the wild type pattern. We conclude that this splice variant most likely represents the only physiologically important mRNA, at least with regard to cardiolipin metabolism.
Vaz
Frédéric M
FM
Departments of Clinical Chemistry and Pediatrics, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, P. O. Box 22700, 1100 DE Amsterdam, The Netherlands. f.m.vaz@amc.uva.nl
Houtkooper
Riekelt H
RH
Valianpour
Fredoen
F
Barth
Peter G
PG
Wanders
Ronald J A
RJ
D000217:Acyltransferases; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000906:Antibodies / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D002308:Cardiolipins / Q000378:metabolism*; D009202:Cardiomyopathies / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D041321:Chromosomes, Human, X; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D005091:Exons; D005808:Genes, Recessive; D005816:Genetic Complementation Test; D008040:Genetic Linkage; D006130:Growth Disorders / Q000235:genetics; D006801:Humans; D013058:Mass Spectrometry; D008956:Models, Chemical; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009135:Muscular Diseases / Q000235:genetics; D016296:Mutagenesis; D009154:Mutation; D009503:Neutropenia / Q000235:genetics; D011506:Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013577:Syndrome; D014157:Transcription Factors
D000906:Antibodies; D002308:Cardiolipins; D018076:DNA, Complementary; D011506:Proteins; D014157:Transcription Factors; D002244:Carbon; D004247:DNA; D000217:Acyltransferases; C108675:TAFAZZIN protein, human