3RBH

Structure of alginate export protein AlgE from Pseudomonas aeruginosa

3RBH の概要

• エントリーDOI: 10.2210/pdb3rbh/pdb
• 分子名称: Alginate production protein AlgE, CALCIUM ION, 1,2-ETHANEDIOL, ... (5 entities in total)
• 機能のキーワード: beta-barrel, alginate export, membrane protein, transport protein
• 由来する生物種: Pseudomonas aeruginosa
• 細胞内の位置: Cell outer membrane; Peripheral membrane protein: P18895
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 225670.41

構造登録者

Whitney, J.C.,Hay, I.D.,Li, C.,Eckford, P.D.,Robinson, H.,Amaya, M.F.,Wood, L.F.,Ohman, D.E.,Bear, C.E.,Rehm, B.H.,Howell, P.L. (登録日: 2011-03-29, 公開日: 2011-07-27, 最終更新日: 2024-10-16)

主引用文献

Whitney, J.C.,Hay, I.D.,Li, C.,Eckford, P.D.,Robinson, H.,Amaya, M.F.,Wood, L.F.,Ohman, D.E.,Bear, C.E.,Rehm, B.H.,Lynne Howell, P.
Structural basis for alginate secretion across the bacterial outer membrane.
Proc.Natl.Acad.Sci.USA, 108:13083-13088, 2011

PubMed Abstract: Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 Å crystal structure of AlgE, which reveals a monomeric 18-stranded β-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 (ΔT8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or ΔL2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with ΔT8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.

PubMed: 21778407
DOI: 10.1073/pnas.1104984108

実験手法

X-RAY DIFFRACTION (2.301 Å)