TY - JOUR
T1 - Enzymatic activity of naturally occurring 1-acylglycerol-3-phosphate-O- acyltransferase 2 mutants associated with congenital generalized lipodystrophy
AU - Haque, Wasim
AU - Garg, Abhimanyu
AU - Agarwal, Anil K.
N1 - Funding Information:
We thank Ruth Giselle Huet, Keliang Xu, and Angela Osborn for technical assistance, Beverly Adams-Huet for statistical analysis, and Robert Butsch for illustrations. This work was supported by the National Institutes of Health Grants R01-DK54387 and M01-RR00633, and by the Southwestern Medical Foundation. W.H. was supported by the NIH fellowship training Grant T32 DK07307.
PY - 2005/2/11
Y1 - 2005/2/11
N2 - Mutations in the gene encoding 1-acylglycerol-3-phosphate-O-acyltransferase 2 (AGPAT2) have been reported in patients with congenital generalized lipodystrophy (CGL). AGPAT2, a 278 amino acid protein, belongs to the acyltransferase enzyme family, and has two conserved motifs, NHX 4D and EGTR, involved in the enzymatic activity. The AGPATs catalyze acylation of lysophosphatidic acid (LPA) to phosphatidic acid (PA) during the biosynthesis of glycerophospholipids and triglycerides from glycerol-3-phosphate. The present studies were designed to determine the enzymatic activity of AGPAT2 mutants found in CGL patients to provide a molecular explanation for the phenotype and to obtain additional information about the structure-function relationship of AGPAT2 protein. The enzymatic activities of the wild type AGPAT2 and mutants were determined in cell lysates of overexpressing Chinese hamster ovary cells by measuring the conversion of [ 3H]LPA to [ 3H]PA in the presence of oleoyl-coenzyme A. Whereas, the R68X, 221delGT, 252delMRT, D180fsX251, and V167fsX183 mutants had markedly reduced enzymatic activity (median <15% of the wild type), the mutants, 140delF, G136R, and L228P, retained median activity ranging from 15% to 40% of the wild type enzyme. However, the missense mutant, A239V, had 90% of the wild type activity. We suggest that reduction in AGPAT2 enzymatic activity underlies the loss of adipose tissue in CGL. Our observations reveal an important role of various carboxy-terminal residues in determining the enzymatic activity of AGPAT2.
AB - Mutations in the gene encoding 1-acylglycerol-3-phosphate-O-acyltransferase 2 (AGPAT2) have been reported in patients with congenital generalized lipodystrophy (CGL). AGPAT2, a 278 amino acid protein, belongs to the acyltransferase enzyme family, and has two conserved motifs, NHX 4D and EGTR, involved in the enzymatic activity. The AGPATs catalyze acylation of lysophosphatidic acid (LPA) to phosphatidic acid (PA) during the biosynthesis of glycerophospholipids and triglycerides from glycerol-3-phosphate. The present studies were designed to determine the enzymatic activity of AGPAT2 mutants found in CGL patients to provide a molecular explanation for the phenotype and to obtain additional information about the structure-function relationship of AGPAT2 protein. The enzymatic activities of the wild type AGPAT2 and mutants were determined in cell lysates of overexpressing Chinese hamster ovary cells by measuring the conversion of [ 3H]LPA to [ 3H]PA in the presence of oleoyl-coenzyme A. Whereas, the R68X, 221delGT, 252delMRT, D180fsX251, and V167fsX183 mutants had markedly reduced enzymatic activity (median <15% of the wild type), the mutants, 140delF, G136R, and L228P, retained median activity ranging from 15% to 40% of the wild type enzyme. However, the missense mutant, A239V, had 90% of the wild type activity. We suggest that reduction in AGPAT2 enzymatic activity underlies the loss of adipose tissue in CGL. Our observations reveal an important role of various carboxy-terminal residues in determining the enzymatic activity of AGPAT2.
KW - AGPAT
KW - Acyltransferase
KW - Lipodystrophy
KW - Lysophosphatidic acid
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U2 - 10.1016/j.bbrc.2004.12.024
DO - 10.1016/j.bbrc.2004.12.024
M3 - Article
C2 - 15629135
AN - SCOPUS:11144253452
SN - 0006-291X
VL - 327
SP - 446
EP - 453
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 2
ER -