Jiao Jian, Xia Yan, Zhang Yingli, Wu Xueli, Liu Chonghuai, Feng Jiancan, Zheng Xianbo, Song Shangwei, Bai Tuanhui, Song Chunhui, Wang Miaomiao, Pang Hongguang
College of Horticulture, Henan Agricultural University, Zhengzhou, China.
Henan Key Laboratory of Fruit and Cucurbit Biology, Zhengzhou, China.
Front Genet. 2021 Nov 15;12:746392. doi: 10.3389/fgene.2021.746392. eCollection 2021.
Melatonin acts both as an antioxidant and as a growth regulatory substance in plants. endophytic bacterium has been shown to produce melatonin and increase plant resistance to abiotic stressors through increasing endogenous melatonin. However, in bacteria, genes are still not known to be melatonin-related. Here, we reported that the bacterial phenylalanine 4-hydroxylase (PAH) may be involved in the 5-hydroxytryptophan (5-HTP) biosynthesis and further influenced the subsequent production of melatonin in . The purified PAH protein of not only hydroxylated phenylalanine but also exhibited l-tryptophan (l-Trp) hydroxylase activity by converting l-Trp to 5-HTP . However, bacterial PAH displayed lower activity and affinity for l-Trp than l-phenylalanine. Notably, the PAH deletion of blocked melatonin production by causing a significant decline in 5-HTP levels and thus decreased the resistance to abiotic stress. Overall, this study revealed a possible role for bacterial PAH in controlling 5-HTP and melatonin biosynthesis in bacteria, and expanded the current knowledge of melatonin production in microorganisms.
褪黑素在植物中既作为抗氧化剂又作为生长调节物质发挥作用。已表明内生细菌通过增加内源性褪黑素产生褪黑素并增强植物对非生物胁迫的抗性。然而，在细菌中，与褪黑素相关的基因仍不为人所知。在此，我们报道细菌苯丙氨酸4-羟化酶（PAH）可能参与5-羟色氨酸（5-HTP）的生物合成，并进一步影响随后在[具体细菌名称未给出]中褪黑素的产生。[具体细菌名称未给出]的纯化PAH蛋白不仅能使苯丙氨酸羟基化，还通过将L-色氨酸（L-Trp）转化为5-HTP表现出L-色氨酸羟化酶活性。然而，细菌PAH对L-Trp的活性和亲和力低于L-苯丙氨酸。值得注意的是，[具体细菌名称未给出]的PAH缺失通过导致5-HTP水平显著下降而阻断了褪黑素的产生，从而降低了对非生物胁迫的抗性。总体而言，本研究揭示了细菌PAH在控制细菌中5-HTP和褪黑素生物合成中的可能作用，并扩展了目前对微生物中褪黑素产生的认识。
