SlyA regulates motA and motB, virulence and stress-related genes under conditions induced by the PhoP-PhoQ system in Dickeya dadantii 3937

We previously showed that SlyA of Dickeya dadantii 3937 plays an important role in virulence toward plants, and that the Delta slyA mutant is hypermotile, whereas flagellum synthesis and flagellin production are indistinguishable from the wild type. Here we show that motility factors, including the distance of continuous directed movement, time for that movement and speed, were significantly higher in the Delta slyA mutant than in the wild type. Remarkably, transcription levels of motA and motB, that are involved in flagellar rotation, were elevated in the Delta slyA mutant, suggesting that the mutant's hypermotility was due to an increase in flagellar rotation. In low (10 mu M) magnesium medium that activates the PhoP-PhoQ system, growth and virulence of the Delta slyA mutant were much lower than for the wild type; expression of motA, motB, mgtA, pelA, pelB, pelC, pelD, pelE, pell, indA, tolC, sodC, acsA and hrpN were also reduced in the mutant. Interestingly, motA, motB, pelD, pelE, pell, sodC and indA were also reduced in phoP and phoQ mutants. Because the SlyA protein directly binds to the promoter region of PhoP, SlyA regulates virulence by controlling multiple pathogenicity-related genes directly and/or at least by controlling PhoP in D. dadantii 3937 when magnesium is low. (C) 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

我们先前表明， Dickeya dadantii 3937的SlyA在对植物的致病性中起重要作用，并且ΔslyA突变体具有超强运动性，而鞭毛合成和鞭毛蛋白产生与野生型无差异。在此我们表明，运动因子，包括连续定向运动的距离、该运动的时间和速度，在ΔslyA突变体中均显著高于野生型。值得注意的是，参与鞭毛旋转的motA和motB的转录水平在ΔslyA突变体中升高，这表明该突变体的超强运动性是由于鞭毛旋转增加所致。在激活PhoP - PhoQ系统的低（10 μM）镁培养基中，ΔslyA突变体的生长和致病性远低于野生型；该突变体中motA、motB、mgtA、pelA、pelB、pelC、pelD、pelE、pell、indA、tolC、sodC、acsA和hrpN的表达也降低。有趣的是，在phoP和phoQ突变体中，motA、motB、pelD、pelE、pell、sodC和indA也降低。由于SlyA蛋白直接结合到PhoP的启动子区域，在镁含量低时，SlyA通过直接控制多个致病性相关基因和/或至少通过控制Dickeya dadantii 3937中的PhoP来调节致病性。（C）2015年巴斯德研究所。由爱思唯尔马松公司出版。保留所有权利。