Expression and localization of HrpA1: A protein of Xanthomonas campestris pv vesicatoria essential for pathogenicity and induction of the hypersensitive reaction
Expression and localization of HrpA1: A protein of Xanthomonas campestris pv vesicatoria essential for pathogenicity and induction of the hypersensitive reaction
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DOI：
10.1128/jb.178.4.1061-1069.1996
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发表时间：
1996-02-01
影响因子：
3.2
通讯作者：
Bonas, U
中科院分区：
文献类型：
--
作者：
Wengelnik, K;Marie, C;Bonas, U
辣椒和番茄病原菌辣椒黄单胞菌（Xanthomonas campestris pv, vesicatoria）的hrp簇既能对易感寄主植物产生致病性，又能诱导抗性植物产生超敏反应。hrpA位点位于25 kb hrp区域的左端，编码一个64 kda的hrp蛋白HrpA1，该蛋白属于PuID超家族，参与II型和III型蛋白的分泌。在这项研究中，我们开发了一种不含任何植物源性分子的培养基，在体外诱导hrpA的表达。hrpA转录起始位点定位在hrpB8基因的编码区，该基因是hrpB操纵子的最后一个基因。可诱导的hrpA启动子与已知的启动子元件或其他基因座无同源性。实验。hrpA的表达不依赖于hrp调控基因hrpX。HrpA1蛋白的氨基酸序列预计包含一个n端信号序列，没有进一步的跨膜结构域，并且具有丰富的β -片延伸。在大肠杆菌细胞中，HrpA1的表达可以诱导psp操纵子，就像它的一些对应物一样，这表明它们的功能有一定的共性，并且HrpA1可以形成多聚体。hrpA1蛋白产物经特异性多克隆抗体鉴定。细胞分离研究表明，HrpA1蛋白定位于X， campestris pv的外膜。实验。BrpA1是Hrp分泌系统中第一个在原始生物体中定位确定的成分。
The hrp cluster of the pepper and tomato pathogen Xanthomonas campestris pv, vesicatoria is required for both pathogenicity on susceptible host plants and induction of the hypersensitive reaction on resistant plants. The hrpA locus is located at the left end of the 25-kb hrp region and encodes a single 64-kDa Hrp protein, HrpA1, which belongs to the PuID superfamily of proteins involved in type II and type III protein secretion. In this study, we developed a defined medium without any plant-derived molecules that induces expression of hrpA in vitro. The hrpA transcription start site was mapped in the coding region of the hrpB8 gene, which is the last gene of the hrpB operon. The inducible hrpA promoter shows no homology to known promoter elements or other hip loci of X. campestris pv. vesicatoria. hrpA expression was shown to be independent of the hrp regulatory gene hrpX. The amino acid sequence of the HrpA1 protein is predicted to contain an N-terminal signal sequence and no further transmembrane domains and to be rich in beta-sheet stretches. Expression of HrpA1 in Escherichia coli cells causes induction of the psp operon like some of its counterparts, suggesting some commonality of function and that HrpA1 forms multimers. The protein product of hrpA1 was identified by using a specific polyclonal antibody. Cell fractionation studies demonstrated that the HrpA1 protein is localized in the outer membrane of X, campestris pv. vesicatoria. BrpA1 is the first component of the Hrp secretion system whose localization has been determined in the original organism.