Yan Lan, Zhang Qizhong, Virolle Marie-Joelle, Xu Delin
Department of Ecology, Institute of Hydrobiology, School of Life Science and Technology, Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Engineering Research Center of Tropical and Subtropical Aquatic Ecological Engineering, Ministry of Education, Jinan University, Guangzhou, PR China.
Group "Energetic Metabolism of Streptomyces ", Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, INRA, Université Paris-Saclay, Gif-sur-Yvette Cedex, France.
PLoS One. 2017 Mar 30;12(3):e0174781. doi: 10.1371/journal.pone.0174781. eCollection 2017.
Regulators of the WhiB-like (wbl) family are playing important role in the complex regulation of metabolic and morphological differentiation in Streptomyces. In this study, we investigated the role of wblI, a member of this family, in the regulation of secondary metabolite production in Streptomyces lividans. The over-expression of wblI was correlated with an enhanced biosynthesis of undecylprodigiosin and actinorhodin and with a reduction of the biosynthesis of yCPK and of the grey spore pigment encoded by the whiE locus. Five regulatory targets of WblI were identified using in vitro formaldehyde crosslinking and confirmed by EMSA and qRT-PCR. These included the promoter regions of wblI itself, two genes of the ACT cluster (actVA3 and the intergenic region between the divergently orientated genes actII-1 and actII-2) and that of wblA, another member of the Wbl family. Quantitative RT-PCR analysis indicated that the expression of actVA3 encoding a protein of unknown function as well as that of actII-1, a TetR regulator repressing the expression of actII-2, encoding the ACT transporter, were down regulated in the WblI over-expressing strain. Consistently the expression of the transporter actII-2 was up-regulated. The expression of WblA, that is known to have a negative impact on ACT biosynthesis, was strongly down regulated in the WblI over-expressing strain. These data are consistent with the positive impact that WblI over-expression has on ACT biosynthesis. The latter might result from direct activation of ACT biosynthesis and export and from repression of the expression of WblA, a likely indirect, repressor of ACT biosynthesis.
WhiB样（wbl）家族的调控因子在链霉菌代谢和形态分化的复杂调控中发挥着重要作用。在本研究中，我们调查了该家族成员wblI在天蓝色链霉菌次级代谢产物合成调控中的作用。wblI的过表达与十一烷基灵菌红素和放线紫红素生物合成的增强以及yCPK和由whiE位点编码的灰色孢子色素生物合成的减少相关。通过体外甲醛交联鉴定了WblI的五个调控靶点，并通过电泳迁移率变动分析（EMSA）和定量逆转录聚合酶链反应（qRT-PCR）进行了确认。这些靶点包括wblI自身的启动子区域、ACT簇的两个基因（actVA3以及方向相反的基因actII-1和actII-2之间的基因间区域）以及Wbl家族的另一个成员wblA的启动子区域。定量RT-PCR分析表明，在过表达WblI的菌株中，编码未知功能蛋白质的actVA3以及抑制ACT转运蛋白编码基因actII-2表达的TetR调控因子actII-1的表达下调。与之一致的是，转运蛋白actII-2的表达上调。已知对ACT生物合成有负面影响的WblA的表达在过表达WblI的菌株中强烈下调。这些数据与WblI过表达对ACT生物合成的积极影响一致。后者可能是由于ACT生物合成和输出的直接激活以及WblA表达的抑制，WblA可能是ACT生物合成的间接抑制因子。
