Systematic Mutagenesis of All Predicted gntR Genes in Xanthomonas campestris pv. campestris Reveals a GntR Family Transcriptional Regulator Controlling Hypersensitive Response and Virulence
Systematic Mutagenesis of All Predicted gntR Genes in Xanthomonas campestris pv. campestris Reveals a GntR Family Transcriptional Regulator Controlling Hypersensitive Response and Virulence
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野油菜黄单胞菌所有预测 gntR 基因的系统诱变。
DOI：
10.1094/mpmi-08-10-0180
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发表时间：
2011-09-01
影响因子：
3.5
通讯作者：
Tang, Ji-Liang
中科院分区：
文献类型：
--
作者：
An, Shi-Qi;Lu, Guang-Tao;Tang, Ji-Liang
GntR家族是细菌中最丰富和分布最广泛的螺旋-转角-螺旋转录调节因子之一。植物病原菌野油菜黄单胞菌致病变种基因组中的六个开放阅读框。预测campestris编码GntR调节子。所有六个预测的GntR编码基因分别诱变和突变体，其中五个成功地获得。植物病害反应试验表明，其中一个产物属于YtrA亚家族，被命名为HpaR 1，参与过敏反应（HR）和毒力。电泳迁移率改变实验和体外转录实验表明HpaR 1可以通过与其启动子序列结合来抑制自身的转录水平，表明HpaR 1表达的自动调节反馈抑制机制。启动子gusA报告和逆转录聚合酶链反应分析表明，HpaR 1积极和消极影响HR和致病性（HRP）基因在宿主植物和标准媒体的表达，分别。组成型表达的关键hrp调节，hrpG，在hpaRI突变体可以绕过HpaR 1的诱导野生型HR的要求，这表明HpaR 1通过hrpG调节编码III型分泌系统的hrp基因的表达。
The GntR family is one of the most abundant and widely distributed groups of helix-turn-helix transcriptional regulators in bacteria. Six open reading frames in the genome of the plant pathogen Xanthomonas campestris pv. campestris were predicted to encode GntR regulators. All six of the predicted GntR-encoding genes were individually mutagenized and mutants from five of them were successfully obtained. Plant disease response assays revealed that one, whose product belongs to the YtrA subfamily and has been named HpaR1, is involved in the hypersensitive response (HR) and virulence. Electrophoretic mobility shift assays and in vitro transcription assays revealed that HpaR1 could repress its own transcription level through binding to its promoter sequence, indicating an autoregulatory feedback inhibition mechanism for HpaR1 expression. Promoter-gusA reporter and reverse-transcription polymerase chain reaction analyses revealed that HpaR1 positively and negatively affects the expression of HR and pathogenicity (hrp) genes in host plant and standard media, respectively. Constitutive expression of the key hrp regulator, hrpG, in the hpaRI mutant could bypass the requirement of HpaR1 for the induction of wild-type HR, suggesting that HpaR1 regulates the expression of hrp genes that encode the type III secretion system via hrpG.