Pérez-Mendoza Daniel, Felipe Antonia, Ferreiro María Dolores, Sanjuán Juan, Gallegos María Trinidad
Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain.
Front Microbiol. 2019 Apr 17;10:746. doi: 10.3389/fmicb.2019.00746. eCollection 2019.
pv. tomato DC3000 carries the operon for the synthesis of acetylated cellulose, whose production is stimulated by increasing the intracellular levels of the second messenger c-di-GMP. This enhances air-liquid biofilm formation and generates a wrinkly colony morphotype in solid media. In the present study we show that cellulose production is a complex process regulated at multiple levels and involving different players in this bacterium. Using different approaches, including lectrophoretic obility hift ssay (EMSA) and footprint analysis, we demonstrated the interrelated role of two transcriptional regulators, AmrZ and FleQ, over cellulose production in Pto DC3000 and the influence of c-di-GMP in this process. Under physiological c-di-GMP levels, both regulators bind directly to adjacent regions at the promoter inhibiting its expression. However, just FleQ responds to c-di-GMP releasing from its operator site and converting from a repressor to an activator of cellulose production. The additive effect of the double mutation on the expression of , together with the fact that they are not cross-regulated at the transcriptional level, suggest that FleQ and AmrZ behave as independent regulators, unlike what has been described in other species. Furthermore, this dual co-regulation exerted by AmrZ and FleQ is not limited to cellulose production, but also affects other important phenotypes in Pto DC3000, such as motility and virulence.
番茄致病变种DC3000携带用于合成乙酰化纤维素的操纵子，其产量可通过提高第二信使环二鸟苷酸（c-di-GMP）的细胞内水平来刺激。这增强了气液生物膜的形成，并在固体培养基中产生褶皱菌落形态。在本研究中，我们表明纤维素的产生是一个在多个水平上受到调控的复杂过程，并且涉及该细菌中的不同参与者。使用不同的方法，包括电泳迁移率变动分析（EMSA）和足迹分析，我们证明了两个转录调节因子AmrZ和FleQ在Pto DC3000中对纤维素产生的相互关联作用以及c-di-GMP在此过程中的影响。在生理c-di-GMP水平下，这两个调节因子都直接结合到启动子的相邻区域，抑制其表达。然而，只有FleQ对从其操纵位点释放的c-di-GMP作出反应，并从纤维素产生的阻遏物转变为激活物。双突变对 表达的累加效应，以及它们在转录水平上不相互交叉调控的事实，表明FleQ和AmrZ表现为独立的调节因子，这与在其他物种中所描述的情况不同。此外，AmrZ和FleQ施加的这种双重共同调节不仅限于纤维素的产生，还影响Pto DC3000中的其他重要表型，如运动性和毒力。
