PorM, a core component of bacterial type IX secretion system, forms a dimer with a unique kinked-rod shape
PorM, a core component of bacterial type IX secretion system, forms a dimer with a unique kinked-rod shape
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PorM 是细菌 IX 型分泌系统的核心成分，形成具有独特扭杆形状的二聚体
DOI：
10.1016/j.bbrc.2020.08.018
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发表时间：
2020
影响因子：
3.1
通讯作者：
Imada Katsumi
中科院分区：
文献类型：
--
作者：
Sato Keiko;Okada Kodai;Nakayama Koji;Imada Katsumi
牙龈卟啉单胞菌（Porphyromonas gingivalis）是牙周病的主要致病菌，通过IX型分泌系统（T9SS）分泌牙龈卟啉蛋白酶等毒力因子。T9SS由跨周质核心复合物、外膜转位子复合物和附着在外膜上的细胞表面复合物组成。PorM是跨周质核心复合物的主要组分，并且被认为连接外膜组分与内膜组分。最近的结构研究表明，GldM的周质区，一个PorM同源的滑行细菌，由四个结构域，并形成一个直杆形状的二聚体。然而，只有片段结构是已知的PorM。此外，PorM片段结构之一显示扭结。在这里，我们显示的结构的整个结构的周质区的PorM（PorMp）在3.7毫米的分辨率。PorMp由四个结构域组成，并形成具有不对称的扭结棒形状的独特二聚体结构。结构和随后的突变分析显示，R204稳定D1和D2结构域之间的扭结，并且是牙龈卟啉菌蛋白酶分泌所必需的，这表明PorM的扭结结构对于功能性T9SS形成是重要的。
Porphyromonas gingivalis,which is a major pathogen of the periodontal disease, secrets virulence factors such as gingipain proteases via the type IX secretion system (T9SS). T9SS consists of a trans-periplasmic core complex, the outer membrane translocon complex and the cell-surface complex attached on the outer membrane. PorM is a major component of the trans-periplasmic core complex and is believed to connect the outer membrane component with the inner membrane component. Recent structural studies have revealed that the periplasmic region of GldM, a PorM homolog of a gliding bacterium, consist of four domains and forms a dimer with a straight rod shape. However, only fragment structures are known for PorM. Moreover, one of the PorM fragment structure shows a kink. Here we show the structure of the entire structure of the periplasmic region of PorM (PorMp) at 3.7 Å resolution. PorMp is made up of four domains and forms a unique dimeric structure with an asymmetric, kinked-rod shape. The structure and the following mutational analysis revealed that R204 stabilizes the kink between the D1 and D2 domains and is essential for gingipains secretion, suggesting that the kinked structure of PorM is important for the functional T9SS formation.