Characterization of the GntR family regulator HpaR1 of the crucifer black rot pathogen Xanthomonas campestris pathovar campestris.
Characterization of the GntR family regulator HpaR1 of the crucifer black rot pathogen Xanthomonas campestris pathovar campestris.
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DOI：
10.1038/srep19862
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发表时间：
2016-01-28
影响因子：
4.6
通讯作者：
Tang JL
中科院分区：
文献类型：
--
作者：
Su HZ;Wu L;Qi YH;Liu GF;Lu GT;Tang JL
从野油菜黄单胞菌中鉴定出GntR家族转录调控因子HpaR1。Campestris先前已经被证明可以积极地调节与过敏反应和致病性有关的基因，并自动抑制其自身的表达。在这里，我们证明了HpaR1是一种全球调节因子，它积极地调节多种生物学过程，包括黄原胶多糖的产生、胞外酶活性、细胞运动性和对各种胁迫的耐受性。为了研究HpaR1的调控机制，我们从黄原胶多糖的产生开始，黄原胶多糖的产生受一组树胶基因的控制。这些都是由口香糖发起人执导的。HpaR1的破坏显著降低了Gumb的转录，凝胶迁移率改变分析表明HpaR1直接与Gumb启动子相互作用。DNA酶I足迹分析表明，HpaR1RNA聚合酶分别与−21~+10和−41~+29之间的序列结合。此外，体外转录分析表明，HpaR1促进了RNA聚合酶与Gumb启动子的结合，导致其转录增强。这些结果表明，HpaR1通过一种类似但不同的机制调节Gumb转录，到目前为止，只有一些MerR家族的转录激活子使用HpaR1。
The GntR family transcription regulator HpaR1 identified from Xanthomonas campestris pv. campestris has been previously shown to positively regulate the genes responsible for hypersensitive reaction and pathogenicity and to autorepress its own expression. Here, we demonstrated that HpaR1 is a global regulator that positively regulates diverse biological processes, including xanthan polysaccharide production, extracellular enzyme activity, cell motility and tolerance to various stresses. To investigate the regulatory mechanisms of HpaR1, we began with xanthan polysaccharide production, which is governed by a cluster of gum genes. These are directed by the gumB promoter. Disruption of HpaR1 significantly reduced gumB transcription and an electrophoretic mobility shift assay demonstrated that HpaR1 interacts directly with gumB promoter. DNase I footprint analysis revealed that HpaR1 and RNA polymerase were bound to the sequences extending from −21 to +10 and −41 to +29 relative to the transcription initiation site of gumB, respectively. Furthermore, in vitro transcription assays showed that HpaR1 facilitated the binding of RNA polymerase to gumB promoter, leading to an enhancement of its transcription. These results suggest that HpaR1 regulates gumB transcription via a mechanism similar but different to what was found, until now, to only be used by some MerR family transcription activators.