Identification of the human mitochondrial linoleoyl-coenzyme A monolysocardiolipin acyltransferase (MLCL AT-1).

Abstract

Here we report the identification of a previously uncharacterized human protein as the human monolysocardiolipin acyltransferase-1 (MLCL AT-1). Pig liver mitochondria were treated with n-butyl alcohol followed by Q-Sepharose chromatography, preparative gel electrophoresis, cytidine diphosphate-1,2-diacyl-sn-glycerol-Sepharose chromatography, and finally monolysocardiolipin-adriamycin-agarose affinity chromatography. Elution with either monolysocardiolipin or linoleoyl coenzyme A revealed a major band at 74 kDa with high specific activity (2,300 pmol/min/mg) for the acylation of monolysocardiolipin to cardiolipin using [1-(14)C]linoleoyl coenzyme A as substrate. Matrix-assisted laser desorption ionization time-of-flight-mass spectrometry analysis followed by search of the Mascot protein data base revealed peptide matches consistent with a 59-kDa protein identified as unknown human protein (GenBank(TM) protein accession number AAX93141; nucleotide accession number AC011742.3). The purified human recombinant MLCL AT-1 protein utilized linoleoyl coenzyme A > oleoyl coenzyme A > palmitoyl coenzyme A for the specific acylation of monolysocardiolipin to cardiolipin. Expression of MLCL AT-1 in HeLa cells increased mitochondrial monolysocardiolipin acyltransferase activity and [1-(14)C]linoleic acid incorporated into cardiolipin, whereas RNA interference knockdown of MLCL AT-1 in HeLa cells resulted in reduction in enzyme activity and [1-(14)C]linoleic acid incorporated into cardiolipin. In contrast, expression of MLCL AT-1 in HeLa cells did not alter [1-(14)C]oleic or [1-(14)C]palmitate incorporation into cardiolipin indicating in vivo specificity for the remodeling of cardiolipin with linoleate. Finally, expression of MLCL AT-1 in Barth syndrome lymphoblasts, which exhibit cardiolipin levels 20% that of normal lymphoblasts, increased mitochondrial monolysocardiolipin acyltransferase activity, [1-(14)C]linoleic acid incorporation into cardiolipin, cardiolipin mass, and succinate dehydrogenase (mitochondrial complex II) activity compared with mock-transfected Barth syndrome lymphoblasts. The results identify MLCL AT-1 as a human mitochondrial monolysocardiolipin acyltransferase involved in the remodeling of cardiolipin.

• Authors: William A Taylor, Grant M Hatch
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 284 Issue 44 Pg. 30360-71 (Oct 30 2009) ISSN: 1083-351X [Electronic] United States
• PMID: 19737925 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cardiolipins
• Mitochondrial Proteins
• Oleic Acid
• Palmitic Acid
• Linoleic Acid
• Acyltransferases
• monolysocardiolipin acyltransferase

Topics

• Acyltransferases (isolation & purification)
• Animals
• Cardiolipins (metabolism)
• Cardiomyopathies
• Computational Biology
• HeLa Cells
• Humans
• Linoleic Acid (metabolism)
• Lymphocytes (metabolism, pathology)
• Mitochondria, Liver (enzymology)
• Mitochondrial Proteins (isolation & purification)
• Molecular Sequence Data
• Oleic Acid (metabolism)
• Palmitic Acid (metabolism)
• Swine