Rapid Triacylglycerol Turnover in Chlamydomonas reinhardtii Requires a Lipase with Broad Substrate Specificity
Rapid Triacylglycerol Turnover in Chlamydomonas reinhardtii Requires a Lipase with Broad Substrate Specificity
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DOI：
10.1128/ec.00268-12
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发表时间：
2012-12-01
期刊：
影响因子：
--
通讯作者：
Kuo, Min-Hao
中科院分区：
文献类型：
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作者：
Li, Xiaobo;Benning, Christoph;Kuo, Min-Hao
当被剥夺氮(N)时，光合微藻莱茵衣藻（Chlamydomonas reinhardtii）会积累大量的甘油三酯（TAGs），使其成为生物燃料的有希望的来源。已经发现了与TAG积累条件相关的显著转录变化，这表明TAG代谢的关键酶可能在TAG合成和分解过程中表达波动的酶中。利用一株酿酒酵母脂肪酶缺失突变株进行功能互补，我们基于其抑制酵母菌脂肪酶缺失相关表型的能力，从衣藻中鉴定出了CrLIP1基因。在衣藻中，当衣藻培养物被可逆地剥夺氮时，发现CrLIP1转录物水平与TAG丰度呈负相关。从大肠杆菌中表达和纯化的CrLIP1蛋白表现出对二酰基甘油（DAG）和极性脂质的溶脂活性。CrLIP1的脂肪酶结构域与人类的两种DAG脂肪酶DAGL α和DAGL β最为相似。通过人工微rna降低CrLIP1转录物的丰度，证实了CrLIP1参与衣藻的TAG水解，当N重新供给时，CrLIP1转录物的丰度明显延迟TAG的脂解。综上所述，这些数据表明，CrLIP1主要通过降解可能由TAG水解产生的DAG来促进衣藻中TAG的周转。
When deprived of nitrogen (N), the photosynthetic microalga Chlamydomonas reinhardtii accumulates large quantities of triacylglycerols (TAGs), making it a promising source of biofuel. Prominent transcriptional changes associated with the conditions leading to TAG accumulation have been found, suggesting that the key enzymes for TAG metabolism might be among those that fluctuate in their expression during TAG synthesis and breakdown. Using a Saccharomyces cerevisiae lipase null mutant strain for functional complementation, we identified the CrLIP1 gene from Chlamydomonas based on its ability to suppress the lipase deficiency-related phenotypes of the yeast mutant. In Chlamydomonas, an inverse correlation was found between the CrLIP1 transcript level and TAG abundance when Chlamydomonas cultures were reversibly deprived of N. The CrLIP1 protein expressed and purified from Escherichia coli exhibited lipolytic activity against diacylglycerol (DAG) and polar lipids. The lipase domain of CrLIP1 is most similar to two human DAG lipases, DAGL alpha and DAGL beta. The involvement of CrLIP1 in Chlamydomonas TAG hydrolysis was corroborated by reducing the abundance of the CrLIP1 transcript with an artificial micro-RNA, which resulted in an apparent delay in TAG lipolysis when N was resupplied. Together, these data suggest that CrLIP1 facilitates TAG turnover in Chlamydomonas primarily by degrading the DAG presumably generated from TAG hydrolysis.