Robert-Seilaniantz Alexandre, Shan Libo, Zhou Jian-Min, Tang Xiaoyan
Department of Plant Pathology, Kansas State University, Manhattan 66506-5502, USA.
Mol Plant Microbe Interact. 2006 Feb;19(2):130-8. doi: 10.1094/MPMI-19-0130.
The HopPtoF locus in Pseudomonas syringae pv. tomato DC3000 harbors two genes, ShcF and HopF2 (previously named ShcF(Pto) and HopF(Pto)), that encode a type III chaperone and a cognate effector protein, respectively. The HopF2 gene has a rare initiation codon, ATA that was reported to be functional only in mitochondrial genes. Here, we report that the native HopPtoF locus of DC3000 confers an avirulence function in tobacco W38 plants, indicating that the ATA start codon directs the synthesis of a functional effector. However, disruption of HopF2 in DC3000 genome did not alter the bacterial virulence in tomato plants. The HopPtoF locus displayed a measurable virulence activity in two strains of P. syringae pv. tomato when the ATA start codon was changed to ATG, and this change also elevated the avirulence function in W38 plants. HopF2 contains a putative myristoylation site. Mutational analysis indicated that this site is required for plasma membrane localization and virulence and avirulence activities of HopF2.
丁香假单胞菌番茄致病变种DC3000中的HopPtoF位点含有两个基因，即ShcF和HopF2（以前分别命名为ShcF(Pto)和HopF(Pto)），它们分别编码一个III型伴侣蛋白和一个同源效应蛋白。HopF2基因有一个罕见的起始密码子ATA，据报道该密码子仅在线粒体基因中起作用。在此，我们报道DC3000的天然HopPtoF位点在烟草W38植株中赋予无毒功能，这表明ATA起始密码子指导合成一种功能性效应蛋白。然而，DC3000基因组中HopF2的缺失并未改变其在番茄植株中的毒力。当ATA起始密码子变为ATG时，HopPtoF位点在两种丁香假单胞菌番茄致病变种菌株中表现出可测量的毒力活性，并且这种变化也增强了其在W38植株中的无毒功能。HopF2含有一个假定的肉豆蔻酰化位点。突变分析表明，该位点是HopF2定位于质膜以及其毒力和无毒活性所必需的。
