Shi Haoran, Wang Jiabin, Li Shanshan, Liu Chongxi, Li Lei, Dong Zhuoxu, Ye Lan, Wang Xiangjing, Zhang Yanyan, Xiang Wensheng
Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin, 150030, China.
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
Synth Syst Biotechnol. 2024 Nov 9;10(1):237-246. doi: 10.1016/j.synbio.2024.11.001. eCollection 2025.
Guvermectin, a purine nucleoside natural product produced by the genus S, has recently been registered as a new biopesticide to boost rice yield. Despite its economic and agricultural significance, the regulatory mechanisms of guvermectin biosynthesis remain essentially unknown, hindering industrial production and widespread agricultural application. Here, we examined the roles of two LacI family regulators, and , located within and adjacent to the guvermectin biosynthesis cluster, respectively, in guvermectin production in NEAU6. GvmR activated the expression of the guvermectin cluster by binding to the promoters of , , and , while GvmR2 repressed the guvermectin cluster via competitive binding to promoters containing GvmR-binding sites, specifically, a 14-bp palindromic sequences: 5'-RTCATWCGYATGAY-3' (R = G/A, W = A/T, Y = T/C). Moreover, GvmR indirectly activates the expression of while GvmR2 feedback inhibits transcription, suggesting a functional interaction between the two regulators for coordinating guvermectin production. Overexpression of via the T7 RNA polymerase-T7 promoter system in the mutant significantly elevated guvermectin production by 125 % (from 631 mg L to 1422 mg L), compared to the parental strain NEAU6. This suggested that combinatorial manipulation of and is useful for improving guvermectin production. These findings enrich our knowledge of the regulatory network for guvermectin biosynthesis, and offer key targets and effective strategies for high-titer guvermectin production.
谷缬菌素是由链霉菌属产生的一种嘌呤核苷天然产物，最近已作为一种新型生物农药登记注册，用于提高水稻产量。尽管谷缬菌素具有经济和农业意义，但其生物合成的调控机制基本上仍不清楚，这阻碍了其工业化生产和广泛的农业应用。在此，我们研究了分别位于谷缬菌素生物合成簇内和相邻位置的两个LacI家族调控因子GvmR和GvmR2在NEAU6中谷缬菌素生产中的作用。GvmR通过与gvmA、gvmC和gvmE的启动子结合来激活谷缬菌素簇的表达，而GvmR2通过竞争性结合含有GvmR结合位点的启动子，特别是一个14bp的回文序列：5'-RTCATWCGYATGAY-3'（R = G/A，W = A/T，Y = T/C）来抑制谷缬菌素簇。此外，GvmR间接激活gvmE的表达，而GvmR2反馈抑制gvmE的转录，这表明这两个调控因子之间存在功能相互作用以协调谷缬菌素的生产。通过T7 RNA聚合酶-T7启动子系统在GvmR2突变体中过表达GvmR，与亲本菌株NEAU6相比，谷缬菌素产量显著提高了125%（从631 mg/L提高到1422 mg/L）。这表明对GvmR和GvmR2进行组合操作有助于提高谷缬菌素的产量。这些发现丰富了我们对谷缬菌素生物合成调控网络的认识，并为高产量谷缬菌素的生产提供了关键靶点和有效策略。
