Han Qian, Zhou Changhe, Wu Shuchi, Liu Yi, Triplett Lindsay, Miao Jiamin, Tokuhisa James, Deblais Loïc, Robinson Howard, Leach Jan E, Li Jianyong, Zhao Bingyu
Laboratory of Tropical Veterinary Medicine and Vector Biology, and Hainan Key Laboratory of Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University, Haikou 570228, Hainan, China; Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA.
Department of Horticulture, Virginia Tech, Blacksburg, VA 24061, USA.
Structure. 2015 Oct 6;23(10):1900-1909. doi: 10.1016/j.str.2015.06.030. Epub 2015 Sep 3.
Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak (BLS) disease on rice plants. Xoc delivers a type III effector AvrRxo1-ORF1 into rice plant cells that can be recognized by disease resistance (R) protein Rxo1, and triggers resistance to BLS disease. However, the mechanism and virulence role of AvrRxo1 is not known. In the genome of Xoc, AvrRxo1-ORF1 is adjacent to another gene AvrRxo1-ORF2, which was predicted to encode a molecular chaperone of AvrRxo1-ORF1. We report the co-purification and crystallization of the AvrRxo1-ORF1:AvrRxo1-ORF2 tetramer complex at 1.64 Å resolution. AvrRxo1-ORF1 has a T4 polynucleotide kinase domain, and expression of AvrRxo1-ORF1 suppresses bacterial growth in a manner dependent on the kinase motif. Although AvrRxo1-ORF2 binds AvrRxo1-ORF1, it is structurally different from typical effector-binding chaperones, in that it has a distinct fold containing a novel kinase-binding domain. AvrRxo1-ORF2 functions to suppress the bacteriostatic activity of AvrRxo1-ORF1 in bacterial cells.
水稻细菌性条斑病菌（Xanthomonas oryzae pv. oryzicola，Xoc）可引发水稻细菌性条斑病。Xoc将III型效应蛋白AvrRxo1-ORF1注入水稻细胞，该蛋白可被抗病（R）蛋白Rxo1识别，并触发对细菌性条斑病的抗性。然而，AvrRxo1的作用机制和毒力作用尚不清楚。在Xoc的基因组中，AvrRxo1-ORF1与另一个基因AvrRxo1-ORF2相邻，后者被预测编码AvrRxo1-ORF1的分子伴侣。我们报道了AvrRxo1-ORF1:AvrRxo1-ORF2四聚体复合物在1.64 Å分辨率下的共纯化和结晶情况。AvrRxo1-ORF1具有T4多核苷酸激酶结构域，AvrRxo1-ORF1的表达以一种依赖激酶基序的方式抑制细菌生长。尽管AvrRxo1-ORF2与AvrRxo1-ORF1结合，但其结构与典型的效应蛋白结合伴侣不同，因为它具有包含新型激酶结合结构域的独特折叠。AvrRxo1-ORF2的功能是抑制AvrRxo1-ORF1在细菌细胞中的抑菌活性。
