Ehrlichia chaffeensis Exploits Host SUMOylation Pathways To Mediate Effector-Host Interactions and Promote Intracellular Survival
Ehrlichia chaffeensis Exploits Host SUMOylation Pathways To Mediate Effector-Host Interactions and Promote Intracellular Survival
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DOI：
10.1128/iai.01984-14
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发表时间：
2014-10-01
影响因子：
3.1
通讯作者：
McBride, Jere W.
中科院分区：
文献类型：
--
作者：
Dunphy, Paige Selvy;Luo, Tian;McBride, Jere W.
查菲埃里希体是一种专性细胞内革兰氏阴性细菌，选择性感染单核吞噬细胞。我们最近报道了E. chaffeensis利用1型分泌（T1 S）系统输出串联重复蛋白（TRP）效应物，并证明这些效应物与功能多样的宿主蛋白质阵列相互作用。通过这些相互作用，TRP效应器调节宿主细胞功能;然而，这些相互作用的分子基础及其在埃里希体病理生物学中的作用尚未明确。在这项研究中，我们描述了第一个细菌蛋白翻译后修饰（PTM）的小泛素样修饰（SUMO）。急诊chaffeensis T1 S效应子TRP 120在体外和人细胞中在羧基末端典型共有SUMO缀合基序处缀合至SUMO。在人细胞中，TRP 120选择性地与SUMO 2/3同种型结合。TRP 120 SUMO化的破坏扰乱了与已知宿主蛋白的相互作用，通过预测的SUMO相互作用基序依赖性和非依赖性机制。E. chaffeensis感染没有导致全局宿主SUMO化蛋白质谱的显著变化，但观察到主要SUMO 1与埃里希体包涵体的稳健共定位。用小分子抑制剂抑制SUMO通路对E. Chaffeensis的复制和TRP 120相互作用蛋白polycomb组环指蛋白5（PCGF 5）的募集到包涵体中，表明SUMO途径对细胞内存活至关重要。这项研究揭示了埃里希体对SUMO通路的新利用，该通路促进了篡夺宿主并创造一个容许的细胞内生态位所必需的效应子-真核生物相互作用。
Ehrlichia chaffeensis is an obligately intracellular Gram-negative bacterium that selectively infects mononuclear phagocytes. We recently reported that E. chaffeensis utilizes a type 1 secretion (T1S) system to export tandem repeat protein (TRP) effectors and demonstrated that these effectors interact with a functionally diverse array of host proteins. By way of these interactions, TRP effectors modulate host cell functions; however, the molecular basis of these interactions and their roles in ehrlichial pathobiology are not well defined. In this study, we describe the first bacterial protein posttranslational modification (PTM) by the small ubiquitin-like modifier (SUMO). The E. chaffeensis T1S effector TRP120 is conjugated to SUMO at a carboxy-terminal canonical consensus SUMO conjugation motif in vitro and in human cells. In human cells, TRP120 was selectively conjugated with SUMO2/3 isoforms. Disruption of TRP120 SUMOylation perturbed interactions with known host proteins, through predicted SUMO interaction motif-dependent and -independent mechanisms. E. chaffeensis infection did not result in dramatic changes in the global host SUMOylated protein profile, but a robust colocalization of predominately SUMO1 with ehrlichial inclusions was observed. Inhibiting the SUMO pathway with a small-molecule inhibitor had a significant impact on E. chaffeensis replication and recruitment of the TRP120-interacting protein polycomb group ring finger protein 5 (PCGF5) to the inclusion, indicating that the SUMO pathway is critical for intracellular survival. This study reveals the novel exploitation of the SUMO pathway by Ehrlichia, which facilitates effector-eukaryote interactions necessary to usurp the host and create a permissive intracellular niche.