Identification of a putative alternate sigma factor and characterization of a multicomponent regulatory cascade controlling the expression of Pseudomonas syringae pv. syringae Pss61 hrp and hrmA genes
Identification of a putative alternate sigma factor and characterization of a multicomponent regulatory cascade controlling the expression of Pseudomonas syringae pv. syringae Pss61 hrp and hrmA genes
复制标题
DOI：
10.1128/jb.176.4.1025-1036.1994
复制
发表时间：
1994-02
影响因子：
3.2
通讯作者：
Yingxian Xiao;S. Heu;J. Yi;Y. Lu;S. Hutcheson
中科院分区：
文献类型：
--
作者：
Yingxian Xiao;S. Heu;J. Yi;Y. Lu;S. Hutcheson
假单胞菌hrp和hrmA基因控制的致病性和过敏反应的启发和avr基因控制主机范围已被证明以前被调节的碳，氮，pH值，渗透压，和假设的植物因素。在P. pss 61，hrp互补组II和XIII的失活减少了质粒携带的hrmA '-lacZ融合体的表达。将hrp区域II和XIII克隆在单独的质粒上，并显示出在大肠杆菌MC 4100转化体中增强hrmA启动子的活性至少100倍。第XIII区的核苷酸序列显示两个开放阅读框架（hrpR和hrpS），其推导产物与P. eriningae pv. phaseolicola NPS 3121 HrpS的基因，并且都与双组分信号转导系统的NtrC家族相关。HrpR和HrpS与蛋白质家族的大多数成员不同，缺乏调节调节活性的氨基末端结构域。在区域II内鉴定了单一开放阅读框hrpL，其产物与铜绿假单胞菌的推定替代σ因子AlgU以及相关替代σ因子具有同源性。关键结构域是部分保守的。在Pss 61中hrpS的失活抑制了由pYXPL 1 R携带的质粒携带的hrpL '-lacZ融合体的表达，并且用携带hrpRS的质粒转化MC 4100（pYXPL 1 R）使hrpL启动子活性增加至少200倍。无论是hrpS还是hrpR，当克隆在单独的质粒上时，单独激活hrpL启动子活性。当由lac启动子指导时，hrpL的表达足以表达一组质粒携带的hrmA ′-、hrpJ ′-和hrpZ ′-lacZ融合体，而不依赖于其它hrp基因。结果表明，hrpRS和hrpL是一个调节级联的一部分，其中HrpR和HrpS激活hrpL的表达和HrpL，一个假定的西格玛因子，诱导HrpL响应基因的表达。
The Pseudomonas syringae hrp and hrmA genes controlling pathogenicity and elicitation of the hypersensitive response and the avr genes controlling host range have been shown previously to be regulated by carbon, nitrogen, pH, osmolarity, and hypothetical plant factors. In P. syringae pv. syringae Pss61, inactivation of hrp complementation groups II and XIII reduced expression of a plasmid-borne hrmA'-lacZ fusion. The hrp regions II and XIII were cloned on separate plasmids and shown to enhance the activity of the hrmA promoter in Escherichia coli MC4100 transformants at least 100-fold. The nucleotide sequence of region XIII revealed two open reading frames (hrpR and hrpS) whose deduced products share homology with P. syringae pv. phaseolicola NPS3121 HrpS and are both related to the NtrC family of two-component signal transduction systems. HrpR and HrpS differ from most members of the protein family by lacking an amino-terminal domain which modulates the regulatory activity. A single open reading frame, hrpL, whose product shares homology with AlgU, a putative alternate sigma factor of P. aeruginosa, as well as with the related alternate sigma factors was identified within region II. Key domains are partially conserved. Inactivation of hrpS in Pss61 repressed expression of a plasmid-borne hrpL'-lacZ fusion carried by pYXPL1R, and transformation of MC4100(pYXPL1R) with a plasmid carrying hrpRS increased hrpL promoter activity at least 200-fold. Neither hrpS nor hrpR, when cloned on separate plasmids, activated the hrpL promoter activity individually. The expression of hrpL when directed by a lac promoter was sufficient to express a set of plasmid-borne hrmA'-, hrpJ'-, and hrpZ'-lacZ fusions independently of other hrp genes. The results indicate that hrpRS and hrpL are part of a regulatory cascade in which HrpR and HrpS activate expression of hrpL and HrpL, a putative sigma factor, induces expression of HrpL-responsive genes.