EcpA, an extracellular protease, is a specific virulence factor required by Xanthomonas oryzae pv. oryzicola but not by X. oryzae pv. oryzae in rice.
EcpA, an extracellular protease, is a specific virulence factor required by Xanthomonas oryzae pv. oryzicola but not by X. oryzae pv. oryzae in rice.
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DOI：
10.1099/mic.0.059964-0
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发表时间：
2012-09
期刊：
影响因子：
1.5
通讯作者：
Huasong Zou;Xue Song;Lifang Zou;Liang Yuan;Yu-rong Li;W. Guo;Y. Che;Wenxiang Zhao;Y. Duan
中科院分区：
文献类型：
--
作者：
Huasong Zou;Xue Song;Lifang Zou;Liang Yuan;Yu-rong Li;W. Guo;Y. Che;Wenxiang Zhao;Y. Duan
本文报道了12株水稻白叶枯病菌（Xanthomonas oryzae pv.从Tn 5-标记突变体文库中回收稻生菌（Xoc）RS 105菌株。在当前的研究中，绘制了每个突变体中Tn 5插入位点的图谱。编码Ⅱ型分泌器组分、cAMP调节蛋白、膜蛋白酶亚基、S-腺苷甲硫氨酸脱羧酶酶原和胞外蛋白酶（ecpA（Xoc））的基因突变部分或完全消除了胞外蛋白酶活性（ECPA）并降低了水稻的毒力。除RΔecpA外，其它突变体均能诱导ecpA（Xoc）的转录。RΔecpA与ecpA（Xoc）的反式互补恢复了ECPA、致病力和细菌在植物中的生长。纯化的EcpA（Xoc）诱导类似于当注射到水稻叶片中时由病原体诱导的失绿和坏死症状。EcpA（Xoc）的异源表达赋予维管细菌X ECPA。oryzaepv.稻（Xoo）和非致病性大肠杆菌。遗传分析表明，Xoo PXO 99（A）和Xoc RS 105中EcpA的C-末端残基不同，EcpA（Xoo）中的移码现象可能是Xoo中EcpA活性缺失的原因。综上所述，EcpA（Xoc）是Xoc的组织特异性毒力因子，而不是Xoo的组织特异性毒力因子，尽管这两种致病型是水稻上密切相关的细菌病原体。
Previously, 12 protease-deficient mutants of the Xanthomonas oryzae pv. oryzicola (Xoc) RS105 strain were recovered from a Tn5-tagged mutant library. In the current study, the Tn5 insertion site in each mutant was mapped. Mutations in genes encoding components of the type II secretion apparatus, cAMP regulatory protein, integral membrane protease subunit, S-adenosylmethionine decarboxylase proenzyme and extracellular protease (ecpA(Xoc)) either partially or completely abolished extracellular protease activity (ECPA) and reduced virulence in rice. Transcription of ecpA(Xoc) was induced in planta in all the mutants except RΔecpA. Complementation of RΔecpA with ecpA(Xoc) in trans restored ECPA, virulence and bacterial growth in planta. Purified EcpA(Xoc) induced chlorosis- and necrosis-like symptoms similar to those induced by the pathogen when injected into rice leaves. Heterologous expression of ecpA(Xoc) conferred ECPA upon the vascular bacterium X. oryzae pv. oryzae (Xoo) and upon non-pathogenic Escherichia coli. Genetic analysis demonstrated that the C-terminal residues of EcpA in Xoo PXO99(A) and Xoc RS105 are different, and a frame shift in ecpA(Xoo) may explain the absence of EcpA activity in Xoo. Collectively, these results suggest that EcpA(Xoc) is a tissue-specific virulence factor for Xoc but not Xoo, although the two pathovars are closely related bacterial pathogens of rice.