Huang H C, Lin R H, Chang C J, Collmer A, Deng W L
Agricultural Biotechnology Laboratories, National Chung-Hsing University, Taichung, Taiwan, R.O.C.
Mol Plant Microbe Interact. 1995 Sep-Oct;8(5):733-46. doi: 10.1094/mpmi-8-0733.
Pseudomonas syringae pv. syringae 61 contains a 25-kb hrp cluster that is sufficient to elicit the hypersensitive response (HR) in nonhost plants. Previous studies have shown that mutations in complementation groups VIII, IX, and XI in the hrp cluster abolished the ability of the bacterium to cause the HR. The sequence of a 3.7-kb SmaI-SstI fragment covering groups VIII and IX now reveals five open reading frames (ORFs) in the same transcript, designated as hrpU, hrpW, hrpO, hrpX, and hrpY, and predicted to encode proteins of 14,795, 23,211, 9,381, 28,489, and 39,957 Da, respectively. The hrpU, hrpW, hrpO, hrpX, and hrpY genes are homologous and arranged colinearly with the yscQ/spa33/spaO, yscR/spa24/spaP, yscS/spa9/spaQ, yscT/spa29/spaR, and yscU/spa40/spaS genes of Yersinia spp., Shigella flexneri, and Salmonella typhimurium, respectively. These proteins also show similarity to Fli/Flh proteins of Bacillus and enteric bacteria. The Ysc and Spa proteins are involved in the secretion of virulence factors, like the Yop and Ipa proteins. Fli/Flh proteins are involved in flagellar biogenesis. The sequence of a 2.9-kb EcoRV-EcoRI DNA fragment containing mainly group XI revealed five ORFs, designated hrpC, hrpD, hrpE, hrpF, and hrpG, predicted to encode proteins of 29,096, 15,184, 21,525, 7,959, and 13,919 Da, respectively. The first three genes belong to an operon containing hrpZ, which encodes an extracellular protein that elicits the HR. hrpF and hrpG are two potential ORFs upstream of hrpH in the hrpH operon. HrpC is homologous to Yersinia YscJ, Pseudomonas solanacearum HrpI, Xanthomonas compestris pv. vesicatoria HrpB3, and Rhizobium fredii NolT. HrpE is similar to YscL of Yersinia spp. P. s. pv. syringae 61 Hrp proteins are most similar to Ysc proteins among those homologs. TnphoA insertions in hrpC, hrpE, hrpW, hrpX, and hrpY abolished the ability of P. s.pv. syringae 61 to secrete HrpZ (harpinPss), as determined by immunoblot analysis of cell-bound and culture supernatant fractions. Thus, many of the proteins required for flagellar biogenesis and virulence protein secretion in plant and animal pathogens may have a common ancestry.
丁香假单胞菌丁香致病变种61含有一个25 kb的hrp基因簇，该基因簇足以在非寄主植物中引发超敏反应（HR）。先前的研究表明，hrp基因簇中互补组VIII、IX和XI的突变消除了该细菌引发HR的能力。一个覆盖组VIII和IX的3.7 kb SmaI-SstI片段的序列现在揭示了同一转录本中的五个开放阅读框（ORF），分别命名为hrpU、hrpW、hrpO、hrpX和hrpY，预计分别编码14795、23211、9381、28489和39957 Da的蛋白质。hrpU、hrpW、hrpO、hrpX和hrpY基因是同源的，并且分别与耶尔森氏菌属、福氏志贺氏菌和鼠伤寒沙门氏菌的yscQ/spa33/spaO、yscR/spa24/spaP、yscS/spa9/spaQ、yscT/spa29/spaR和yscU/spa40/spaS基因共线排列。这些蛋白质也与芽孢杆菌和肠道细菌的Fli/Flh蛋白质相似。Ysc和Spa蛋白质参与毒力因子的分泌，如Yop和Ipa蛋白质。Fli/Flh蛋白质参与鞭毛生物合成。一个主要包含组XI的2.9 kb EcoRV-EcoRI DNA片段的序列揭示了五个ORF，命名为hrpC、hrpD、hrpE、hrpF和hrpG，预计分别编码29096、15184、21525、7959和13919 Da的蛋白质。前三个基因属于一个包含hrpZ的操纵子，hrpZ编码一种引发HR的细胞外蛋白质。hrpF和hrpG是hrpH操纵子中hrpH上游的两个潜在ORF。HrpC与耶尔森氏菌的YscJ、茄科假单胞菌的HrpI、野油菜黄单胞菌致病变种泡囊致病变种的HrpB3以及费氏根瘤菌的NolT同源。HrpE与耶尔森氏菌属的YscL相似。丁香假单胞菌丁香致病变种61的Hrp蛋白质在这些同源物中与Ysc蛋白质最相似。通过对细胞结合和培养上清液部分的免疫印迹分析确定，hrpC、hrpE、hrpW、hrpX和hrpY中的TnphoA插入消除了丁香假单胞菌丁香致病变种61分泌HrpZ（harpinPss）的能力。因此，植物和动物病原体中鞭毛生物合成和毒力蛋白分泌所需的许多蛋白质可能有共同的祖先。
