Preston G, Huang H C, He S Y, Collmer A
Department of Plant Pathology, Cornell University, Ithaca, NY 14853, USA.
Mol Plant Microbe Interact. 1995 Sep-Oct;8(5):717-32. doi: 10.1094/mpmi-8-0717.
The Pseudomonas syringae pathovars are composed of host-specific plant pathogens that characteristically elicit the defense-associated hypersensitive response (HR) in nonhost plants. P. s. pv. syringae 61 secretes an HR elicitor, harpinPss (HrpZPss), in a hrp-dependent manner. An internal fragment of the P. s. pv. syringae 61 hrpZ gene was used to clone the hrpZ locus from P. s. pv. glycinea race 4 (bacterial blight of soybean) and P. s. pv. tomato DC3000 (bacterial speck of tomato). DNA sequence analysis revealed that hrpZ is the second ORF in a polycistronic operon. The amino acid sequence identities of HrpZPss/HrpZPsg and HrpZPss/HrpZPst were 79 and 63%, respectively. Although none of the HrpZ proteins showed significant overall sequence similarity with other known proteins, HrpZPst contained a 24-amino acid sequence that is homologous with a region of the PopA1 elicitor protein of the tomato pathogen, Pseudomonas solanacearum GMI1000. hrpA, the upstream ORF, was highly divergent: The amino acid sequence identities of HrpAPss/HrpAPsg and HrpAPss/HrpAPst were 91 and 28%, respectively, and no HrpA sequence showed similarity to known proteins. In contrast, the predicted products of the downstream ORFs in P. s. pv. syringae and P. s. pv. tomato, hrpB, hrpC, hrpD, and hrpE showed varying levels of similarity to those of yscI, yscJ, yscK, and yscL. These are colinearly arranged genes in the virC locus of Yersinia spp., which are involved in the secretion of the Yop virulence proteins via the type III pathway. The similarity of the Ysc proteins was generally stronger in comparisons with the P. s. pv. tomato Hrp proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
丁香假单胞菌致病型由宿主特异性植物病原体组成，其特征是在非宿主植物中引发与防御相关的超敏反应（HR）。丁香假单胞菌丁香致病型61以hrp依赖的方式分泌一种HR激发子，即harpinPss（HrpZPss）。利用丁香假单胞菌丁香致病型61 hrpZ基因的一个内部片段，从大豆疫霉4号小种（大豆细菌性疫病）和番茄假单胞菌致病型DC3000（番茄细菌性斑点病）中克隆hrpZ位点。DNA序列分析表明，hrpZ是一个多顺反子操纵子中的第二个开放阅读框。HrpZPss/HrpZPsg和HrpZPss/HrpZPst的氨基酸序列同一性分别为79%和63%。虽然没有一种HrpZ蛋白与其他已知蛋白显示出显著的整体序列相似性，但HrpZPst包含一个24个氨基酸的序列，该序列与番茄病原体茄科雷尔氏菌GMI1000的PopA1激发子蛋白的一个区域同源。上游开放阅读框hrpA高度多样化：HrpAPss/HrpAPsg和HrpAPss/HrpAPst的氨基酸序列同一性分别为91%和28%，且没有HrpA序列与已知蛋白显示出相似性。相比之下，丁香假单胞菌致病型和番茄假单胞菌致病型中预测的下游开放阅读框hrpB、hrpC、hrpD和hrpE的产物与yscI、yscJ、yscK和yscL的产物显示出不同程度的相似性。这些是耶尔森氏菌属virC位点中线性排列的基因，它们通过III型途径参与Yop毒力蛋白的分泌。与番茄假单胞菌致病型的Hrp蛋白相比，Ysc蛋白的相似性通常更强。（摘要截短至250字）
