Helical structure of the needle of the type III secretion system of Shigella flexneri.

Journal article

Gram-negative bacteria commonly interact with animal and plant hosts using type III secretion systems (TTSSs) for translocation of proteins into eukaryotic cells during infection. 10 of the 25 TTSS-encoding genes are homologous to components of the bacterial flagellar basal body, which the TTSS needle complex morphologically resembles. This indicates a common ancestry, although no TTSS sequence homologues for the genes encoding the flagellum are found. We here present an approximately 16-A structure of the central component, the needle, of the TTSS. Although the needle subunit is significantly smaller and shares no sequence homology with the flagellar hook and filament, it shares a common helical architecture ( approximately 5.6 subunits/turn, 24-A helical pitch). This common architecture implies that there will be further mechanistic analogies in the functioning of these two bacterial systems.

Authors: Cordes, F; Komoriya, K; Larquet, E; Yang, S; Egelman, E

• Publication status: Published
• Journal: Journal of biological chemistry
• Volume: 278
• Issue: 19
• Pages: 17103-17107
• Publication date: 2003-05-01
• DOI: 10.1074/jbc.m300091200
• EISSN: 1083-351X
• ISSN: 0021-9258
• Language: English
• Keywords: Shigella flexneri; Protein Transport; Protein Conformation; Bacterial Proteins; Gene Expression Regulation, Bacterial; Flagella; Image Processing, Computer-Assisted