3J0R

Model of a type III secretion system needle based on a 7 Angstrom resolution cryoEM map

3J0R の概要

• エントリーDOI: 10.2210/pdb3j0r/pdb
• EMDBエントリー: 5352
• 分子名称: Protein mxiH (1 entity in total)
• 機能のキーワード: helical assembly, protein transport
• 由来する生物種: Shigella flexneri
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 9141.07

構造登録者

Fujii, T.,Cheung, M.,Blanco, A.,Kato, T.,Blocker, A.J.,Namba, K. (登録日: 2011-11-03, 公開日: 2012-02-29, 最終更新日: 2024-02-21)

主引用文献

Fujii, T.,Cheung, M.,Blanco, A.,Kato, T.,Blocker, A.J.,Namba, K.
Structure of a type III secretion needle at 7-A resolution provides insights into its assembly and signaling mechanisms.
Proc.Natl.Acad.Sci.USA, 109:4461-4466, 2012

PubMed Abstract: Type III secretion systems of Gram-negative bacteria form injection devices that deliver effector proteins into eukaryotic cells during infection. They span both bacterial membranes and the extracellular space to connect with the host cell plasma membrane. Their extracellular portion is a needle-like, hollow tube that serves as a secretion conduit for effector proteins. The needle of Shigella flexneri is approximately 50-nm long and 7-nm thick and is made by the helical assembly of one protein, MxiH. We provide a 7-Å resolution 3D image reconstruction of the Shigella needle by electron cryomicroscopy, which resolves α-helices and a β-hairpin that has never been observed in the crystal and solution structures of needle proteins, including MxiH. An atomic model of the needle based on the 3D-density map, in comparison with that of the bacterial-flagellar filament, provides insights into how such a thin tubular structure is stably assembled by intricate intermolecular interactions. The map also illuminates how the needle-length control protein functions as a ruler within the central channel during export of MxiH for assembly at the distal end of the needle, and how the secretion-activation signal may be transduced through a conformational change of the needle upon host-cell contact.

PubMed: 22388746
DOI: 10.1073/pnas.1116126109

実験手法

ELECTRON MICROSCOPY (7.7 Å)