LIPM, Université de Toulouse, INRA, CNRS, INPT, Castanet-Tolosan, France.
Institute of Biology, Genetics Department, Martin Luther University Halle-Wittenberg, D-23 06099, Halle, (Saale), Germany.
Sci Rep. 2017 Jul 7;7(1):4879. doi: 10.1038/s41598-017-04853-9.
Plant pathogenic bacteria exerts their pathogenicity through the injection of large repertoires of type III effectors (T3Es) into plant cells, a mechanism controlled in part by type III chaperones (T3Cs). In Ralstonia solanacearum, the causal agent of bacterial wilt, little is known about the control of type III secretion at the post-translational level. Here, we provide evidence that the HpaB and HpaD proteins do act as bona fide R. solanacearum class IB chaperones that associate with several T3Es. Both proteins can dimerize but do not interact with each other. After screening 38 T3Es for direct interactions, we highlighted specific and common interacting partners, thus revealing the first picture of the R. solanacearum T3C-T3E network. We demonstrated that the function of HpaB is conserved in two phytopathogenic bacteria, R. solanacearum and Xanthomonas campestris pv. vesicatoria (Xcv). HpaB from Xcv is able to functionally complement a R. solanacearum hpaB mutant for hypersensitive response elicitation on tobacco plants. Likewise, Xcv is able to translocate a heterologous T3E from R. solanacearum in an HpaB-dependent manner. This study underlines the central role of the HpaB class IB chaperone family and its potential contribution to the bacterial plasticity to acquire and deliver new virulence factors.
植物病原细菌通过向植物细胞注射大量 III 型效应物 (T3E) 来发挥其致病性,这一机制部分受 III 型伴侣 (T3C) 控制。在茄科雷尔氏菌(引起细菌性萎蔫病的病原体)中,对翻译后水平的 III 型分泌的控制知之甚少。在这里,我们提供的证据表明,HpaB 和 HpaD 蛋白确实作为茄科雷尔氏菌类 I B 伴侣发挥作用,与几种 T3E 相关联。这两种蛋白都可以二聚化,但彼此不相互作用。在对 38 种 T3E 进行直接相互作用筛选后,我们突出了特定和共同的相互作用伙伴,从而揭示了茄科雷尔氏菌 T3C-T3E 网络的第一张图片。我们证明了 HpaB 的功能在两种植物病原细菌茄科雷尔氏菌和野油菜黄单胞菌 pv.vesicatoria (Xcv) 中是保守的。Xcv 的 HpaB 能够在烟草植物上功能性地补充茄科雷尔氏菌 hpaB 突变体的过敏反应诱导。同样,Xcv 能够以 HpaB 依赖的方式从茄科雷尔氏菌转运异源 T3E。这项研究强调了 HpaB 类 I B 伴侣家族的核心作用及其对细菌获得和输送新毒力因子的可塑性的潜在贡献。