MarR家族转录因子HpaR和XC0449协同调控野油菜黄单胞菌致病性

MarR family transcription regulator HpaR and XC0449 coordinately regulate the virulence of Xanthomonas campestris pv. campestris

摘要:

MarR家族转录因子广泛存在于细菌及古生菌中，并灵活、精细地调控多种毒力、抗胁迫及抗生素相关的生理生化途径。在野油菜黄单胞菌中，MarR家族转录因子HpaR (XC2827) 的失活会显著降低细菌对于寄主甘蓝的致病力，同时会导致胞外蛋白酶的过量表达。本研究进一步发现，Xcc 8004基因组一共编码9个MarR家族转录因子。表达并纯化其中的HpaR (XC2827) 和XC0449，体外微量热泳动 (MST) 实验及 Pull-down 实验证明二者可以在体外特异性结合。同时，表型检测发现XC0449突变会导致细菌致病力显著下降。通过体外凝胶迁移阻滞试验 (EMSA)、体内qRT-PCR和GUS检测证明，XC0449和HpaR均作为转录激活子协同调控下游致病相关基因XC0705的表达，最终调控细菌毒力及胞外酶合成。

Abstract:

MarR family transcription regulators are ubiquitous among bacteria and archaea. They extensively control multiple cellular processes and elaborately regulate the expression of genes involved in virulence, stress response and antibiotics at translational level. In Xanthomonas campestris pv. campestris, insertional inactivation of MarR family transcription regulator HpaR (XC2827) resulted in significantly decrease in virulence and increase in the production of the extracellular proteases. Here, we reported that the genome of Xcc 8004 encodes nine MarR family transcription regulators. The MarR family transcription regulators, HpaR (XC2827) and XC0449, were heterologous expressed and purified. In vitro MST and Pull-down assay confirmed the physical interaction between HpaR and XC0449. Phenotypical assay determined that deletion of XC0449 resulted in substantial virulence attenuation. In vitro EMSA, in vivo qRT-PCR and GUS activity assay identified that HpaR and XC0449 coordinately act as the transcriptional activator to regulate the expression of the virulence-associated gene XC0705, and eventually control the bacterial virulence and the production of extracellular proteases.