Qian Wei, Han Zhong-Ji, Tao Jun, He Chaozu
State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Mol Plant Microbe Interact. 2008 Aug;21(8):1128-38. doi: 10.1094/MPMI-21-8-1128.
The gram-negative bacterium Xanthomonas campestris pv. campestris is the causal agent of black rot disease of cruciferous plants. Its genome encodes a large repertoire of two-component signal transduction systems (TCSTSs), which consist of histidine kinases and response regulators (RR) to monitor and respond to environmental stimuli. To investigate the biological functions of these TCSTS genes, we aimed to inactivate all 54 RR genes in X. campestris pv. campestris ATCC 33913, and successfully generated 51 viable mutants using the insertion inactivation method. Plant inoculation identified two novel response regulator genes (XCC1958 and XCC3107) that are involved in virulence of this strain. Genetic complementation demonstrated that XCC3107, designated as vgrR (virulence and growth regulator), also affects bacterial growth and activity of extracellular proteases. In addition, we assessed the survival of these mutants under various stresses, including osmotic stress, high sodium concentration, heat shock, and sodium dodecyl sulfate exposure, and identified a number of genes that may be involved in the general stress response of X. campestris pv. campestris. Mutagenesis and phenotypic characterization of RR genes in this study will facilitate future studies on signaling networks in this important phytopathogenic bacterium.
革兰氏阴性菌野油菜黄单胞菌野油菜致病变种是十字花科植物黑腐病的病原体。其基因组编码大量双组分信号转导系统（TCSTSs），该系统由组氨酸激酶和响应调节因子（RR）组成，用于监测和响应环境刺激。为了研究这些TCSTS基因的生物学功能，我们旨在使野油菜黄单胞菌野油菜致病变种ATCC 33913中的所有54个RR基因失活，并使用插入失活方法成功产生了51个存活突变体。植物接种鉴定出两个参与该菌株毒力的新型响应调节因子基因（XCC1958和XCC3107）。遗传互补表明，被命名为vgrR（毒力和生长调节因子）的XCC3107也影响细菌生长和细胞外蛋白酶的活性。此外，我们评估了这些突变体在各种胁迫下的存活率，包括渗透胁迫、高钠浓度、热休克和十二烷基硫酸钠暴露，并鉴定出一些可能参与野油菜黄单胞菌野油菜致病变种一般胁迫反应的基因。本研究中RR基因的诱变和表型特征将有助于未来对这种重要植物病原菌信号网络的研究。
