|YUAN, XIAOCHEN - Jiangsu Academy Agricultural Sciences
|ZENG, QUAN - Connecticut Agricultural Experiment Station
|KHOKHANI, DEVANSHI - University Of Wisconsin
|TIAN, FANG - Chinese Academy Of Agricultural Sciences
|SEVERIN, GEOFFREY - Michigan State University
|WATERS, CHRISTOPHER - Michigan State University
|XU, JINGSHENG - Chinese Academy Of Agricultural Sciences
|ZHOU, XIANG - Zhejiang A & F University
|SUNDIN, GEORGE - Michigan State University
|Ibekwe, Abasiofiok - Mark
|LIU, FENGQUAN - Jiangsu Academy Agricultural Sciences
|YANG, CHING-HONG - University Of Wisconsin
Submitted to: Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2019
Publication Date: 3/20/2019
Citation: Yuan, X., Zeng, Q., Khokhani, D., Tian, F., Severin, G.B., Waters, C.M., Xu, J., Zhou, X., Sundin, G.W., Ibekwe, A.M., Liu, F., Yang, C. 2019. A feed-forward signalling circuit controls bacterial virulence through linking cyclic di-GMP and two mechanistically distinct sRNAs, ArcZ and RsmB. Environmental Microbiology. https://doi.org/10.1111/1462-2920.14603.
Interpretive Summary: Dickeya dadantii is a phytopathogenic bacterium that causes soft-rot, wilt and blight diseases on a wide range of economically important crops such as potato, tomato and chicory. This bacterium can penetrate plant tissues through natural openings and survive in the plant. In this study we investigated the various genes that help the bacteria enter and survive inside plants. We showed that there are multilevel regulations of genes that tightly coordinate the expression of pathogenic factors that precisely control disease processes. The results of this research will be used by growers, researchers, and different state agencies that are involved in potato, tomato and chicory production.
Technical Abstract: Dickeya dadantii is a plant pathogen that causes soft rot disease on vegetable and potato crops. To successfully cause infection, this pathogen needs to coordinately modulate the expression of genes encoding several virulence determinants, including plant cell wall degrading enzymes (PCWDEs), type III secretion system (T3SS) and flagellar motility. Here, we uncover a novel feed-forward signalling circuit for controlling virulence. Global RNA chaperone Hfq interacts with an Hfq-dependent sRNA ArcZ and represses the translation of pecT, encoding a LysR-type transcriptional regulator. We demonstrate that the ability of ArcZ to be processed to a 50'nt 3'- end fragment is essential for its regulation of pecT. PecT down-regulates PCWDE and the T3SS by repressing the expression of a global post-transcriptional regulator- (RsmA-) associated sRNA encoding gene rsmB. In addition, we show that the protein levels of two cyclic di-GMP (c-di-GMP) diguanylate cyclases (DGCs), GcpA and GcpL, are repressed by Hfq. Further studies show that both DGCs are essential for the Hfq-mediated post-transcriptional regulation on RsmB. Overall, our report provides new insights into the interplays between ubiquitous signalling transduction systems that were most studied independently and sheds light on multitiered regulatory mechanisms for a precise disease regulation in bacteria.