Tan Yafang, Liu Wanbing, Zhang Qingwen, Cao Shiyang, Zhao Haihong, Wang Tong, Qi Zhizhen, Han Yanping, Song Yajun, Wang Xiaoyi, Yang Ruifu, Du Zongmin
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
Key Laboratory for Plague Prevention and Control of Qinghai Province 2017-ZJ-Y15, Institute for Endemic Disease Prevention and Control of Qinghai Province, Xining, China.
Infect Immun. 2017 Jul 19;85(8). doi: 10.1128/IAI.01069-16. Print 2017 Aug.
Pathogenic yersiniae harbor a type III secretion system (T3SS) that injects outer protein (Yop) into host cells. YopK has been shown to control Yop translocation and prevent inflammasome recognition of the T3SS by the innate immune system. Here, we demonstrate that YopK inhibits bacterial adherence to host cells by binding to the extracellular matrix adaptor protein matrilin-2 (MATN2). YopK binds to MATN2, and deleting amino acids 91 to 124 disrupts binding of YopK to MATN2. A null mutant exhibits a hyperadhesive phenotype, which could be responsible for the established Yop hypertranslocation phenotype of mutants. Expression of YopK, but not YopK, in a mutant restored the wild-type phenotypes of adhesion and Yop translocation, suggesting that binding to MATN2 might be essential for YopK to inhibit bacterial adhesion and negatively regulate Yop translocation. A green fluorescent protein (GFP)-YopK fusion specifically binds to the endogenous MATN2 on the surface of HeLa cells, whereas GFP-YopK cannot. Addition of purified YopK protein during infection decreased adhesion of to HeLa cells, while YopK protein showed no effect. Taking these results together, we propose a model that the T3SS-secreted YopK hinders bacterial adhesion to HeLa cells by binding to MATN2, which is ubiquitously exposed on eukaryotic cells.
致病性耶尔森菌具有一种III型分泌系统（T3SS），该系统可将外蛋白（Yop）注入宿主细胞。已证明YopK可控制Yop的转运，并防止先天免疫系统对T3SS进行炎性小体识别。在此，我们证明YopK通过与细胞外基质衔接蛋白Ⅱ型基质金属蛋白酶（MATN2）结合来抑制细菌对宿主细胞的黏附。YopK与MATN2结合，缺失第91至124位氨基酸会破坏YopK与MATN2的结合。一个缺失突变体表现出高黏附表型，这可能是该突变体已确定的Yop过度转运表型的原因。在一个突变体中表达YopK而非YopK恢复了黏附及Yop转运的野生型表型，这表明与MATN2结合可能是YopK抑制细菌黏附并负向调节Yop转运所必需的。绿色荧光蛋白（GFP）-YopK融合蛋白特异性结合HeLa细胞表面的内源性MATN2，而GFP-YopK则不能。在感染过程中添加纯化的YopK蛋白可降低对HeLa细胞的黏附，而YopK蛋白则无此作用。综合这些结果，我们提出了一个模型，即T3SS分泌的YopK通过与MATN2结合来阻碍细菌对HeLa细胞的黏附，MATN2在真核细胞上普遍存在。
