The Legionella pneumophila IcmR protein exhibits chaperone activity for IcmQ by preventing its participation in high-molecular-weight complexes
The Legionella pneumophila IcmR protein exhibits chaperone activity for IcmQ by preventing its participation in high-molecular-weight complexes
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DOI：
10.1046/j.1365-2958.2001.02454.x
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发表时间：
2001-06-01
影响因子：
3.6
通讯作者：
Isberg, RR
中科院分区：
文献类型：
--
作者：
Duménil, G;Isberg, RR
军团菌病的一个关键事件是嗜肺军团菌在肺泡巨噬细胞内存活和增殖的能力。细胞内生长所必需的dot/icm基因显示出与编码接合转移系统的基因的序列相似性，并且据信它们负责分泌装置的形成。这里提供的证据表明，IcmR和IcmQ蛋白参与的伴侣-底物的关系类似于观察到的易位蛋白在III型和IV型分泌装置。发现固定化IcmQ有效地结合来自细菌粗提物的IcmR。此外，纯化的IcmR和IcmQ以高亲和力结合。通过免疫共沉淀在体内也观察到这种相互作用。发现IcmR的存在直接影响IcmQ的物理状态。在没有IcmR的情况下，IcmQ在体内和体外都形成了高分子量的复合物，而IcmR阻止并逆转了这些复合物的形成。
A key event in legionellosis is the ability of Legionella pneumophila to survive and proliferate inside alveolar macrophages. The dot/icm genes, which are necessary for intracellular growth, show sequence similarity to genes encoding conjugative transfer systems, and it is believed that they are responsible for the formation of a secretion apparatus. Evidence is provided here that the IcmR and IcmQ proteins participate in a chaperone-substrate relationship similar to that observed for translocated proteins in type III and type IV secretion apparatuses. Immobilized IcmQ was found to bind IcmR from crude bacterial extracts efficiently. Furthermore, purified IcmR and IcmQ bind with high affinity. This interaction was also observed in vivo by co-immunoprecipitation. The presence of IcmR was found to affect the physical state of IcmQ directly. In the absence of IcmR, IcmQ formed high-molecular-weight complexes both in vivo and in vitro, whereas IcmR prevented and reversed the formation of these complexes.