解淀粉芽胞杆菌HZ-12中ysnE参与吲哚-3-乙酸合成的代谢途径研究

Metabolic pathways of ysnE involved in indole-3-acetic acid synthesis in Bacillus amyloliquefaciens HZ-12

摘要:

【目的】吲哚-3-乙酸是调控植物生长发育和生理活动的重要激素，吲哚-3-乙酸N-乙酰转移酶YsnE在吲哚-3-乙酸合成中发挥重要作用，本研究拟解析解淀粉芽胞杆菌中YsnE参与吲哚-3-乙酸合成的代谢途径。【方法】通过基因ysnE缺失和强化表达，分析ysnE对吲哚-3-乙酸合成影响，结合吲哚-3-乙酸合成中间物(吲哚丙酮酸、吲哚乙酰胺、色胺和吲哚乙腈)添加和体外酶转化实验，解析ysnE参与吲哚-3-乙酸合成的代谢途径。【结果】明确了YsnE在解淀粉芽胞杆菌HZ-12吲哚-3-乙酸合成中发挥重要作用。发现ysnE缺失菌株中的吲哚丙酮酸、吲哚乙酰胺和吲哚乙腈利用显著降低，揭示了YsnE主要发挥吲哚丙酮酸脱羧酶YclB和吲哚乙酰胺水解酶/腈水解酶/腈水合酶YhcX的功能，并通过参与吲哚丙酮酸、吲哚乙酰胺和吲哚乙腈途径来影响吲哚-3-乙酸合成。【结论】初步揭示了YsnE通过影响吲哚丙酮酸、吲哚乙酰胺和吲哚乙腈途径参与吲哚-3-乙酸合成的代谢机理，为吲哚-3-乙酸合成途径解析和代谢工程育种构建吲哚-3-乙酸高产菌株奠定了基础。

关键词:吲哚-3-乙酸;解淀粉芽胞杆菌;YsnE;代谢途径

Abstract:

[Objective] Indole-3-acetic acid is crucial for plant growth and development and physiological activities. Indole-3-acetic acid N-acetyltransferase YsnE plays an important part in indole-3-acetic acid synthesis. This study aims to analyze the metabolic pathways of YsnE involved in indole-3-acetic acid synthesis of Bacillus amyloliquefaciens. [Methods] Through deletion and overexpression of ysnE, the role of ysnE in indole-3-acetic acid synthesis was elucidated. Combined with the addition of indole-3-acetic acid synthesis intermediates (indole pyruvic acid (IPA), indole-3-acetamide (IAM), tryptamine (TAM), indole-3-acetonitrile (IAN)) and in vitro enzymatic conversion experiments, the metabolic pathways of ysnE involved in indole-3-acetic acid synthesis were clarified. [Results] YsnE played an important role in indole-3-acetic acid synthesis in B. amyloliquefaciens HZ-12. The amount of IPA, IAM, and IAN consumed in ysnE deletion strain was significantly reduced, and YsnE functioned as indolepyruvate decarboxylase YclB, and indoleacetamide hydrolase/nitrilase/nitrile hydratase YhcX, and affected indole-3-acetic acid synthesis by participating in IPA, IAM, and IAN pathways. [Conclusion] YsnE influences the IPA, IAM, and IAN pathways to involve in indole-3-acetic acid synthesis, which lays a foundation for analysis of indole-3-acetic acid synthesis pathway and breeding strains with high yield of indole-3-acetic acid by metabolic engineering.

Key words:indole-3-acetic acid;Bacillus amyloliquefaciens;YsnE;metabolic pathway