Deng Jie, Wu Qiaofen, Gao Hua, Ou Qian, Wu Bo, Yan Bing, Jiang Chengjian
Guangxi Key Laboratory of Mangrove Conservation and Utilization, Guangxi Mangrove Research Center, Guangxi Academy of Sciences, 92 Changqing Rd., Beihai, Guangxi, PR China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Rd., Nanning, Guangxi, PR China.
Food Technol Biotechnol. 2018 Mar;56(1):117-123. doi: 10.17113/ftb.56.01.18.5415.
l-Cysteine sulfinate decarboxylase (CSD, EC 4.1.1.29), the rate-limiting enzyme in taurine synthesis pathway, catalyzes l-cysteine sulfinic acid to form hypotaurine. Identification of the novel CSD that could improve the biosynthetic efficiency of taurine is important. An unexplored decarboxylase gene named was identified in a previous work through sequence-based screening of uncultured soil microorganisms. Random mutagenesis through sequential error-prone polymerase chain reaction was used in Undec1A. A mutant Undec1A-1180, which was obtained from mutagenesis library, had 5.62-fold higher specific activity than Undec1A at 35 °C and pH=7.0. Molecular docking results indicated that amino acid residues Ala235, Val237, Asp239, Ile267, Ala268, and Lys298 in the Undec1A-1180 protein helped recognize and catalyze the substrate molecules of l-cysteine sulfinic acid. These results could serve as a basis for elucidating the characteristics of the Undec1A-1180. Directed evolution technology is a convenient way to improve the biotechnological applications of metagenome-derived genes.
L-半胱氨酸亚磺酸脱羧酶（CSD，EC 4.1.1.29）是牛磺酸合成途径中的限速酶，催化L-半胱氨酸亚磺酸形成亚牛磺酸。鉴定能够提高牛磺酸生物合成效率的新型CSD具有重要意义。在先前的一项工作中，通过对未培养土壤微生物进行基于序列的筛选，鉴定出一个未被探索的脱羧酶基因。在Undec1A中使用了通过易错聚合酶链反应进行的随机诱变。从诱变文库中获得的突变体Undec1A-1180在35℃和pH = 7.0时比Undec1A具有高5.62倍的比活性。分子对接结果表明，Undec1A-1180蛋白中的氨基酸残基Ala235、Val237、Asp239、Ile267、Ala268和Lys298有助于识别和催化L-半胱氨酸亚磺酸的底物分子。这些结果可为阐明Undec1A-1180的特性提供依据。定向进化技术是提高宏基因组来源基因生物技术应用的便捷方法。
