莱茵衣藻
生物
生物化学
二酰甘油激酶
半乳糖脂
脑苷脂
磷脂
衣原体
酶
膜
叶绿体
突变体
基因
蛋白激酶C
作者
Kang‐Sup Yoon,Danxiang Han,Yantao Li,Milton R. Sommerfeld,Qiang Hu
出处
期刊:The Plant Cell
[Oxford University Press]
日期:2012-09-01
卷期号:24 (9): 3708-3724
被引量:306
标识
DOI:10.1105/tpc.112.100701
摘要
Abstract Many unicellular microalgae produce large amounts (∼20 to 50% of cell dry weight) of triacylglycerols (TAGs) under stress (e.g., nutrient starvation and high light), but the synthesis and physiological role of TAG are poorly understood. We present detailed genetic, biochemical, functional, and physiological analyses of phospholipid:diacylglycerol acyltransferase (PDAT) in the green microalga Chlamydomonas reinhardtii, which catalyzes TAG synthesis via two pathways: transacylation of diacylglycerol (DAG) with acyl groups from phospholipids and galactolipids and DAG:DAG transacylation. We demonstrate that PDAT also possesses acyl hydrolase activities using TAG, phospholipids, galactolipids, and cholesteryl esters as substrates. Artificial microRNA silencing of PDAT in C. reinhardtii alters the membrane lipid composition, reducing the maximum specific growth rate. The data suggest that PDAT-mediated membrane lipid turnover and TAG synthesis is essential for vigorous growth under favorable culture conditions and for membrane lipid degradation with concomitant production of TAG for survival under stress. The strong lipase activity of PDAT with broad substrate specificity suggests that this enzyme could be a potential biocatalyst for industrial lipid hydrolysis and conversion, particularly for biofuel production.
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