Zan Xinyi, Tang Xin, Chu Linfang, Zhao Lina, Chen Haiqin, Chen Yong Q, Chen Wei, Song Yuanda
State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.
Synergistic Innovation Center for Food Safety and Nutrition, Wuxi, People's Republic of China.
J Ind Microbiol Biotechnol. 2016 Oct;43(10):1467-80. doi: 10.1007/s10295-016-1820-0. Epub 2016 Aug 17.
Lipases or triacylglycerol hydrolases are widely spread in nature and are particularly common in the microbial world. The filamentous fungus Mucor circinelloides is a potential lipase producer, as it grows well in triacylglycerol-contained culture media. So far only one lipase from M. circinelloides has been characterized, while the majority of lipases remain unknown in this fungus. In the present study, 47 potential lipase genes in M. circinelloides WJ11 and 30 potential lipase genes in M. circinelloides CBS 277.49 were identified by extensive bioinformatics analysis. An overview of these lipases is presented, including several characteristics, sub-cellular location, phylogenetic analysis and expression profiling of the lipase genes during growth and lipid accumulation. All of these proteins contained the consensus sequence for a classical lipase (GXSXG motif) and were divided into four types including α/β-hydrolase_1, α/β-hydrolase_3, class_3 and GDSL lipase (GDSL) based on gene annotations. Phylogenetic analyses revealed that class_3 family and α/β-hydrolase_3 family were the conserved lipase family in M. circinelloides. Additionally, some lipases also contained a typical acyltransferase motif of H-(X) 4-D, and these lipases may play a dual role in lipid metabolism, catalyzing both lipid hydrolysis and transacylation reactions. The differential expression of all lipase genes were confirmed by quantitative real-time PCR, and the expression profiling were analyzed to predict the possible biological roles of these lipase genes in lipid metabolism in M. circinelloides. We preliminarily hypothesized that lipases may be involved in triacylglycerol degradation, phospholipid synthesis and beta-oxidation. Moreover, the results of sub-cellular localization, the presence of signal peptide and transcriptional analyses of lipase genes indicated that four lipase in WJ11 most likely belong to extracellular lipases with a signal peptide. These findings provide a platform for the selection of candidate lipase genes for further detailed functional study.
脂肪酶或三酰甘油水解酶在自然界广泛分布，在微生物界尤为常见。丝状真菌卷枝毛霉是一种潜在的脂肪酶产生菌，因为它能在含三酰甘油的培养基中良好生长。到目前为止，卷枝毛霉中仅鉴定出一种脂肪酶，而该真菌中的大多数脂肪酶仍不为人知。在本研究中，通过广泛的生物信息学分析，在卷枝毛霉WJ11中鉴定出47个潜在的脂肪酶基因，在卷枝毛霉CBS 277.49中鉴定出30个潜在的脂肪酶基因。本文对这些脂肪酶进行了概述，包括其一些特征、亚细胞定位、系统发育分析以及脂肪酶基因在生长和脂质积累过程中的表达谱分析。所有这些蛋白质都含有经典脂肪酶的共有序列（GXSXG基序），并根据基因注释分为四类，包括α/β-水解酶_1、α/β-水解酶_3、3类和GDSL脂肪酶（GDSL）。系统发育分析表明，3类家族和α/β-水解酶_3家族是卷枝毛霉中保守的脂肪酶家族。此外，一些脂肪酶还含有典型的H-(X) 4-D酰基转移酶基序，这些脂肪酶可能在脂质代谢中发挥双重作用，催化脂质水解和转酰基反应。通过定量实时PCR证实了所有脂肪酶基因的差异表达，并对表达谱进行了分析，以预测这些脂肪酶基因在卷枝毛霉脂质代谢中可能的生物学作用。我们初步推测脂肪酶可能参与三酰甘油降解、磷脂合成和β-氧化。此外，亚细胞定位结果、信号肽的存在以及脂肪酶基因的转录分析表明，WJ11中的四种脂肪酶很可能属于具有信号肽的细胞外脂肪酶。这些发现为选择候选脂肪酶基因进行进一步详细的功能研究提供了一个平台。
