铜绿假单胞菌 PA0833 周质域的晶体结构揭示了一个意想不到的扩大的肽聚糖结合口袋。

Crystal structure of PA0833 periplasmic domain from Pseudomonas aeruginosa reveals an unexpected enlarged peptidoglycan binding pocket.

机构信息

West China Hospital Emergency Department (WCHED), State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, and Collaborative Innovation Center of Biotherapy, Chengdu, Sichuan, 610041, China.

出版信息

Biochem Biophys Res Commun. 2019 Apr 16;511(4):875-881. doi: 10.1016/j.bbrc.2019.02.104. Epub 2019 Mar 5.

DOI:10.1016/j.bbrc.2019.02.104

PMID:30850161

Abstract

PA0833 of Pseudomonas aeruginosa is recently identified as an OmpA C-like protein that is able to interact with bacterial peptidoglycan (PGN). In this study, we reported the biochemical and structural characterization of the PGN-binding periplasmic-domain of PA0833 (PA0833-PD). Via mutagenesis, key residues responsible for engaging PGN were identified, which also enables us to localize the PGN-binding pocket in a 2.0 Å crystal structure solved in this study. In contrast to its homologous proteins (as represented by AbOmpA-PD of Acinetobacter baumannii) that interact with PGN by directly engaging the DAP (diaminopimelate) moiety, PA0833-PD exhibits an enlarged PGN-binding pocket due to residue insertions and the formation of an extra α-helix in one lateral side of the pocket. Accordingly, single DAP molecule does not show detectable interactions with PA0833-PD in solution, highlighting that other PGN-components, in addition to DAP, are also required to restore the full binding capacity observed between PA0833 and PGN.

摘要

铜绿假单胞菌的 PA0833 最近被鉴定为一种 OmpA C 样蛋白，能够与细菌肽聚糖（PGN）相互作用。在本研究中，我们报告了 PA0833（PA0833-PD）与 PGN 结合的周质域的生化和结构特征。通过突变，确定了与 PGN 结合的关键残基，这也使我们能够在本研究中解决的 2.0Å 晶体结构中定位 PGN 结合口袋。与它的同源蛋白（以鲍曼不动杆菌的 AbOmpA-PD 为代表）不同，PA0833-PD 通过直接与 DAP（二氨基庚二酸）部分结合来与 PGN 相互作用，由于插入残基和口袋一侧形成额外的α-螺旋，PA0833-PD 具有更大的 PGN 结合口袋。因此，在溶液中，单个 DAP 分子与 PA0833-PD 没有可检测到的相互作用，这突出表明除了 DAP 之外，PGN 的其他成分也需要恢复在 PA0833 和 PGN 之间观察到的全部结合能力。