Christie Peter J, Atmakuri Krishnamohan, Krishnamoorthy Vidhya, Jakubowski Simon, Cascales Eric
Department of Microbiology and Molecular Genetics, UT-Houston Medical School, Houston, Texas 77030, USA.
Annu Rev Microbiol. 2005;59:451-85. doi: 10.1146/annurev.micro.58.030603.123630.
Type IV secretion (T4S) systems are ancestrally related to bacterial conjugation machines. These systems assemble as a translocation channel, and often also as a surface filament or protein adhesin, at the envelopes of Gram-negative and Gram-positive bacteria. These organelles mediate the transfer of DNA and protein substrates to phylogenetically diverse prokaryotic and eukaryotic target cells. Many basic features of T4S are known, including structures of machine subunits, steps of machine assembly, substrates and substrate recognition mechanisms, and cellular consequences of substrate translocation. A recent advancement also has enabled definition of the translocation route for a DNA substrate through a T4S system of a Gram-negative bacterium. This review emphasizes the dynamics of assembly and function of model conjugation systems and the Agrobacterium tumefaciens VirB/D4 T4S system. We also summarize salient features of the increasingly studied effector translocator systems of mammalian pathogens.
IV型分泌（T4S）系统在进化上与细菌接合机器相关。这些系统组装成一个转运通道，并且通常还会以表面细丝或蛋白质粘附素的形式，出现在革兰氏阴性菌和革兰氏阳性菌的包膜上。这些细胞器介导DNA和蛋白质底物向系统发育上不同的原核和真核靶细胞的转移。T4S的许多基本特征已为人所知，包括机器亚基的结构、机器组装步骤、底物和底物识别机制，以及底物转运的细胞后果。最近的一项进展还使得能够确定DNA底物通过革兰氏阴性菌的T4S系统的转运途径。本综述着重介绍了模型接合系统和根癌土壤杆菌VirB/D4 T4S系统的组装动力学和功能。我们还总结了哺乳动物病原体中越来越受研究的效应器转运体系统的显著特征。
