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

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.