Structure of the translocator domain of a bacterial autotransporter
Structure of the translocator domain of a bacterial autotransporter
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DOI：
10.1038/sj.emboj.7600148
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发表时间：
2004-03-24
期刊：
影响因子：
11.4
通讯作者：
Gros, P
中科院分区：
文献类型：
--
作者：
Oomen, CJ;van Ulsen, P;Gros, P
自身转运蛋白是革兰氏阴性菌的毒力相关蛋白，其通过基于外膜的C-末端延伸（转运结构域）分泌。据推测，该结构域足以使N-末端乘客结构域穿过外膜。我们在这里介绍了脑膜炎奈瑟氏球菌的自转运蛋白NaIP的体外折叠转运域的晶体结构，它揭示了一个12链的β-桶，具有10 × 12.5埃的亲水孔，由N-末端α-螺旋填充。该结构域在体内和体外均具有孔活性。我们的数据是一致的，通过β桶内的亲水通道的转运结构域的模型，并通过由低聚物的转运结构域形成的中央通道的运输模型不一致。然而，孔的尺寸意味着以未折叠形式的分泌结构域的易位。另一种可能涵盖折叠结构域转运的模型是，折叠结构域转运涉及Omp 85复合物，Omp 85复合物是外膜蛋白膜插入所需的机制，autotorpers依赖于Omp 85复合物。
Autotransporters are virulence-related proteins of Gram-negative bacteria that are secreted via an outermembrane-based C-terminal extension, the translocator domain. This domain supposedly is sufficient for the transport of the N-terminal passenger domain across the outer membrane. We present here the crystal structure of the in vitro-folded translocator domain of the autotransporter NaIP from Neisseria meningitidis, which reveals a 12-stranded beta-barrel with a hydrophilic pore of 10 x 12.5 Angstrom that is filled by an N-terminal alpha-helix. The domain has, pore activity in vivo and in vitro. Our data are consistent with the model of passenger-domain transport through the hydrophilic channel within the beta-barrel, and inconsistent with a model for transport through a central channel formed by an oligomer of translocator domains. However, the dimensions of the pore imply translocation of the secreted domain in an unfolded form. An alternative model, possibly covering the transport of folded domains, is that passenger-domain transport involves the Omp85 complex, the machinery required for membrane insertion of outer-membrane proteins, on which autotransporters are dependent.