4XP8

Structure of EtgA D60N mutant

4XP8 の概要

• エントリーDOI: 10.2210/pdb4xp8/pdb
• 分子名称: EtgA protein (2 entities in total)
• 機能のキーワード: peptidoglycan hydrolase, hydrolase
• 由来する生物種: Escherichia coli
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 9886.00

構造登録者

Burkinshaw, B.J.,Worrall, L.J.,Strynadka, N.C.J. (登録日: 2015-01-16, 公開日: 2015-02-18, 最終更新日: 2024-11-20)

主引用文献

Burkinshaw, B.J.,Deng, W.,Lameignere, E.,Wasney, G.A.,Zhu, H.,Worrall, L.J.,Finlay, B.B.,Strynadka, N.C.
Structural Analysis of a Specialized Type III Secretion System Peptidoglycan-cleaving Enzyme.
J.Biol.Chem., 290:10406-10417, 2015

PubMed Abstract: The Gram-negative bacterium enteropathogenic Escherichia coli uses a syringe-like type III secretion system (T3SS) to inject virulence or "effector" proteins into the cytoplasm of host intestinal epithelial cells. To assemble, the T3SS must traverse both bacterial membranes, as well as the peptidoglycan layer. Peptidoglycan is made of repeating N-acetylmuramic acid and N-acetylglucosamine disaccharides cross-linked by pentapeptides to form a tight mesh barrier. Assembly of many macromolecular machines requires a dedicated peptidoglycan lytic enzyme (PG-lytic enzyme) to locally clear peptidoglycan. Here we have solved the first structure of a T3SS-associated PG-lytic enzyme, EtgA from enteropathogenic E. coli. Unexpectedly, the active site of EtgA has features in common with both lytic transglycosylases and hen egg white lysozyme. Most notably, the β-hairpin region resembles that of lysozyme and contains an aspartate that aligns with lysozyme Asp-52 (a residue critical for catalysis), a conservation not observed in other previously characterized lytic transglycosylase families to which the conserved T3SS enzymes had been presumed to belong. Mutation of the EtgA catalytic glutamate, Glu-42, conserved across lytic transglycosylases and hen egg white lysozyme, and this differentiating aspartate diminishes type III secretion in vivo, supporting its essential role in clearing the peptidoglycan for T3SS assembly. Finally, we show that EtgA forms a 1:1 complex with the building block of the polymerized T3SS inner rod component, EscI, and that this interaction enhances PG-lytic activity of EtgA in vitro, collectively providing the necessary strict localization and regulation of the lytic activity to prevent overall cell lysis.

PubMed: 25678709
DOI: 10.1074/jbc.M115.639013

実験手法

X-RAY DIFFRACTION (2.03 Å)