文章基本信息

标题：Amino acids 149 and 294 of human lecithin:cholesterol acyltransferase affect fatty acyl specificity
本地全文：下载
作者：Yue Zhao ; Abraham K. Gebre ; John S. Parks 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2004
卷号：45
期号：12
页码：2310-2316
DOI：10.1194/jlr.M400276-JLR200
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：We identified two regions of human LCAT (hLCAT) that when mutated separately to the corresponding rat sequence (E149A and Y292H/W294F) and transiently expressed in COS-1 cells increased phospholipase A₂ (PLA₂) activity by 5.5- and 2.8-fold, respectively, and increased cholesteryl ester (CE) formation by 2.9- and 1.4-fold, respectively, relative to hLCAT using substrate particles containing 1-16:0,2-20:4- sn -glycero-3-phosphocholine (PAPC). In contrast, both activities with 1-16:0,2-18:1- sn -glycero-3-phosphocholine (POPC) substrate were similar among the three LCAT proteins. The triple mutant (E149A/Y292H/W294F) had increased PLA₂ activity with PAPC similar to that observed with the E149A mutation alone; however, unlike E149A, the triple mutant demonstrated a 50% decrease in activity with POPC for both PLA₂ activity and CE formation, suggesting an interaction between the two regions of LCAT. Additional mutagenesis studies demonstrated that W294F, but not Y292H, increased PLA₂ activity by 3-fold with PAPC without affecting activity with POPC. The E149A/W294F double mutation mimicked the LCAT activity phenotype of the triple mutant (more activity with PAPC, less with POPC). In conclusion, separate mutation of two amino acids in hLCAT to the corresponding rat sequence increases activity with PAPC, whereas the combined mutations increase PAPC and decrease POPC activity, suggesting that these amino acids participate in the LCAT PC binding site and affect fatty acyl specificity.