Structure of the VirB4 ATPase, alone and bound to the core complex of a type IV secretion system
Structure of the VirB4 ATPase, alone and bound to the core complex of a type IV secretion system
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DOI：
10.1073/pnas.1201428109
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发表时间：
2012-07-10
影响因子：
11.1
通讯作者：
Waksman, Gabriel
中科院分区：
文献类型：
--
作者：
Wallden, Karin;Williams, Robert;Waksman, Gabriel
IV型分泌（T4 S）系统介导蛋白质和DNA穿过细菌的细胞包膜的转移。这些系统在细菌致病和抗生素耐药性的水平转移中发挥重要作用。T4 S系统的VirB 4 ATP酶对于系统的组装和底物转移都是必不可少的。在这篇文章中，我们提出的晶体结构的C-末端结构域的Thermoanaerobium pseudethanolicus病毒B4。这种结构与另一种T4 S ATP酶VirD 4的结构惊人地相似，VirD 4是一种与VirB 4只有12%序列同一性的蛋白质。VirB 4结构域作为单体纯化，但即使在核苷酸和DNA存在下，也可以在单体-二聚体平衡中观察到全长蛋白质。我们还报告了负染电子显微镜结构的核心复合物的T4 S系统的大肠杆菌pKM 101质粒，与VirB 4绑定。在这种结构中，VirB 4也是单体，并通过其N-末端结构域与核心的VirB 9蛋白结合。值得注意的是，观察到VirB 4结合到复合物的一侧，在那里它被理想地放置以在底物转移中发挥其已知的调节作用。
Type IV secretion (T4S) systems mediate the transfer of proteins and DNA across the cell envelope of bacteria. These systems play important roles in bacterial pathogenesis and in horizontal transfer of antibiotic resistance. The VirB4 ATPase of the T4S system is essential for both the assembly of the system and substrate transfer. In this article, we present the crystal structure of the C-terminal domain of Thermoanaerobacter pseudethanolicus VirB4. This structure is strikingly similar to that of another T4S ATPase, VirD4, a protein that shares only 12% sequence identity with VirB4. The VirB4 domain purifies as a monomer, but the full-length protein is observed in a monomer-dimer equilibrium, even in the presence of nucleotides and DNAs. We also report the negative stain electron microscopy structure of the core complex of the T4S system of the Escherichia coli pKM101 plasmid, with VirB4 bound. In this structure, VirB4 is also monomeric and bound through its N-terminal domain to the core's VirB9 protein. Remarkably, VirB4 is observed bound to the side of the complex where it is ideally placed to play its known regulatory role in substrate transfer.