Park Ji-Min, Kang Chul-Hyung, Won Sung-Min, Oh Ki-Hoon, Yoon Jung-Hoon
Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, South Korea.
Green Chemistry and Environmental Biotechnology Program, School of Science, University of Science and Technology, Daejeon, South Korea.
Front Microbiol. 2020 Jan 24;10:3069. doi: 10.3389/fmicb.2019.03069. eCollection 2019.
A novel esterase, EstCS1, was isolated from a compost metagenomics library. The EstCS1 protein, which consists of 309 amino acid residues with an anticipated molecular mass of 34 kDa, showed high amino acid sequence identities to predicted esterases and alpha/beta hydrolases (59%) from some cultured bacteria and to predicted lipases/esterases from uncultured bacteria. The phylogenetic analysis suggested that the EstCS1 belongs to the hormone-sensitive lipase family of lipolytic enzyme classification and contains a catalytic triad including Ser155-Asp255-His285. The Ser155 residue of the catalytic triad in the EstCS1 was located in the consensus active-site motif, GXSXG. Besides, a conserved HGGG motif placed in an oxyanion hole of the hormone-sensitive lipase family was discovered, too. The EstCS1 demonstrated the highest activity toward -nitrophenyl propionate (C3) and caproate (C6) and was normally stable up to 60°C with optimal activity at 50°C. In addition, an optimal activity was observed at pH 8, and the EstCS1 possessed its stability within the pH range between 5 and 10. Interestingly, EstCS1 had an outstanding stability in up to 30% (v/v) organic solvents and activity over 50% in the presence of 50% (v/v) acetone, ethanol, dimethyl sulfoxide (DMSO), and ,-dimethylformamide. The EstCS1 hydrolyzed sterically hindered tertiary alcohol esters of -butyl acetate and linalyl acetate. Considering the properties, such as the moderate thermostability, stability against organic solvents, and activity toward esters of tertiary alcohols, the EstCS1 will be worthwhile to be used for organic synthesis and related industrial applications.
从堆肥宏基因组文库中分离出一种新型酯酶EstCS1。EstCS1蛋白由309个氨基酸残基组成，预期分子量为34 kDa，与一些培养细菌预测的酯酶和α/β水解酶具有较高的氨基酸序列同一性（59%），与未培养细菌预测的脂肪酶/酯酶也具有较高的氨基酸序列同一性。系统发育分析表明，EstCS1属于脂解酶分类中的激素敏感脂肪酶家族，包含一个由Ser155-Asp255-His285组成的催化三联体。EstCS1催化三联体中的Ser155残基位于共有活性位点基序GXSXG中。此外，还发现了一个位于激素敏感脂肪酶家族氧负离子孔中的保守HGGG基序。EstCS1对丙酸对硝基苯酯（C3）和己酸（C6）表现出最高活性，在60°C以下通常稳定，最适活性温度为50°C。此外，在pH 8时观察到最佳活性，EstCS1在pH 5至10的范围内具有稳定性。有趣的是，EstCS1在高达30%（v/v）的有机溶剂中具有出色的稳定性，在50%（v/v）的丙酮、乙醇、二甲基亚砜（DMSO）和N,N-二甲基甲酰胺存在下活性超过50%。EstCS1能水解空间位阻较大的叔醇酯，如乙酸叔丁酯和乙酸芳樟酯。考虑到EstCS1具有适度的热稳定性、对有机溶剂的稳定性以及对叔醇酯的活性等特性，它在有机合成及相关工业应用中具有应用价值。
