Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, England.
Acta Crystallogr D Struct Biol. 2018 Jan 1;74(Pt 1):21-29. doi: 10.1107/S2059798317017697.
Vibrio cholerae causes a severe disease that kills thousands of people annually. The outer membrane protein OmpU is the most abundant outer membrane protein in V. cholerae, and has been identified as an important virulence factor that is involved in host-cell interaction and recognition, as well as being critical for the survival of the pathogenic V. cholerae in the host body and in harsh environments. The mechanism of these processes is not well understood owing to a lack of the structure of V. cholerae OmpU. Here, the crystal structure of the V. cholerae OmpU trimer is reported to a resolution of 2.2 Å. The protomer forms a 16-β-stranded barrel with a noncanonical N-terminal coil located in the lumen of the barrel that consists of residues Gly32-Ser42 and is observed to participate in forming the second gate in the pore. By mapping the published functional data onto the OmpU structure, the OmpU structure reinforces the notion that the long extracellular loop L4 with a β-hairpin-like motif may be critical for host-cell binding and invasion, while L3, L4 and L8 are crucially implicated in phage recognition by V. cholerae.
霍乱弧菌会引起一种严重的疾病，每年导致数千人死亡。外膜蛋白 OmpU 是霍乱弧菌中最丰富的外膜蛋白，已被确定为一种重要的毒力因子，它参与宿主细胞的相互作用和识别，对致病性霍乱弧菌在宿主体内和恶劣环境中的存活至关重要。由于缺乏霍乱弧菌 OmpU 的结构，这些过程的机制还不是很清楚。本文报道了分辨率为 2.2 Å 的霍乱弧菌 OmpU 三聚体的晶体结构。单体形成一个 16-β 链桶，非典型的 N 端卷曲位于桶的内腔中，由 Gly32-Ser42 残基组成，观察到其参与形成孔中的第二个门。通过将已发表的功能数据映射到 OmpU 结构上，OmpU 结构强化了这样一种观点，即带有 β-发夹样模体的长细胞外环 L4 可能对宿主细胞的结合和入侵至关重要，而 L3、L4 和 L8 则对噬菌体的识别至关重要。
