Weier Dagmar, Müller Claudia, Gaspers Claudia, Frentzen Margrit
RWTH Aachen University, Institute for Biology I-Botany, Worringerweg 1, 52074 Aachen, Germany.
Biochem Biophys Res Commun. 2005 Sep 9;334(4):1127-34. doi: 10.1016/j.bbrc.2005.06.197.
As phylogenetic ancestors of plant chloroplasts cyanobacteria resemble plastids with respect to lipid and fatty acid composition. These membrane lipids show the typical prokaryotic fatty acid pattern in which the sn-2 position is exclusively esterified by C(16) acyl groups. In the course of de novo glycerolipid biosynthesis this prokaryotic fatty acid pattern is established by the sequential acylation of glycerol-3-phosphate with acyl-ACPs by the activity of different acyltransferases. In silico approaches allowed the identification of putative Synechocystis acyltransferases involved in glycerolipid metabolism. Functional expression studies in Escherichia coli showed that sll1848 codes for a lysophosphatidic acid acyltransferase with a high specificity for 16:0-ACP, whereas slr2060 encodes a lysophospholipid acyltransferase, with a broad acyl-ACP specificity but a strong preference for lysophosphatidyglycerol especially its sn-2 acyl isomer as acyl-acceptor. The generation and analysis of the corresponding Synechocystis knockout mutants revealed that lysophosphatidic acid acyltransferase unlike the lysophospholipid acyltransferase is essential for the vital functions of the cells.
作为植物叶绿体的系统发育祖先，蓝细菌在脂质和脂肪酸组成方面类似于质体。这些膜脂呈现典型的原核脂肪酸模式，其中sn-2位仅被C(16)酰基酯化。在从头甘油olipid生物合成过程中，这种原核脂肪酸模式是通过不同酰基转移酶的活性，将甘油-3-磷酸与酰基-ACP依次酰化而建立的。计算机方法使得能够鉴定参与甘油olipid代谢的推定集胞藻酰基转移酶。在大肠杆菌中的功能表达研究表明，sll1848编码一种对16:0-ACP具有高特异性的溶血磷脂酸酰基转移酶，而slr2060编码一种溶血磷脂酰基转移酶，具有广泛的酰基-ACP特异性，但强烈偏好溶血磷脂酰甘油，尤其是其sn-2酰基异构体作为酰基受体。相应集胞藻敲除突变体的产生和分析表明，与溶血磷脂酰基转移酶不同溶血磷脂酸酰基转移酶对细胞的重要功能至关重要。
