十字花科黑腐病菌III型效应物XopXccR1植物亚细胞定位

Subcellular localization of a type III secreted effector XopXccR1 of Xanthomonas campestris pv. campestris in plant cells

摘要:

[目的] 植物病原细菌通过III型分泌系统（type III secretion system，T3SS）将III型效应物（type III secreted effectors，T3SEs）分泌转运到宿主细胞的不同位点上，进而行使不同的致病功能。本研究旨在确定Xcc 8004 III型效应物中分子量最大的蛋白XopXccR1在植物中的亚细胞定位。[方法] 利用生物信息学方法分析XopXccR1的跨膜信息。通过同源重组方法将XopXccR1全长、N端（1–1220 aa）和C端（1221–2030 aa）分别克隆到植物表达载体pCAMBIA-2300-35S：：EGFP上，利用根癌农杆菌介导的瞬时表达浸染本生烟，通过激光共聚焦显微镜观察亚细胞定位结果。[结果] XopXccR1全长和N端定位在本生烟细胞膜上，而C端定位在细胞质中。[结论] XopXccR1的N端与C端可能分别存在定位信号，N端信号主导全长蛋白的最终定位。

Abstract:

[Objective] Plant pathogenic bacteria can directly deliver the secreted type III effectors (T3SEs) into different sites of host cells through the type III secretion system (T3SS), thereby exercising various pathogenic functions. The purpose of this study was to determine the subcellular localization of the largest T3SE protein XopXccR1 of Xcc 8004 in plants. [Methods] The bioinformatics methods were used to analyze the putative transmembrane region of XopXccR1. To obtain the transient expression Agrobacterium strains, the full-length XopXccR1 without stop codon, the N-terminus (1-1220 aa), and the C-terminus (1221-2030 aa) were ligated to the plant expression vector pCAMBIA-2300-35S::EGFP respectively by homologous recombination. Utilizing Agrobacterium-mediated transient expression to infect Nicotiana benthamiana, the results of subcellular localization were then observed with a laser confocal microscope. [Results] The full-length and the N-terminus of XopXccR1 are mainly localized in the cell membrane of N. benthamiana, while the C-terminus of XopXccR1 in the cytoplasm. [Conclusion] XopXccR1 N-and C-terminus might both have the targeting signals. The targeting signals in the N-terminus of XopXccR1 mainly contributes the final sub-localization of XopXccR1.