Conservation of bacterial protein export system

Conservation of bacterial protein export system

Certain bacteria use a protein complex called the injectisome to deliver proteins into host cells, effectively increasing their pathogenic potential. The injectisome “needle” grows from a protein scaffold around its base called the basal body, which is related to the basal body of the bacterial flagellum. Bacterial proteins destined for export are picked up by an export apparatus complex (EA) inside the basal body. EA then exports the proteins across bacterial envelope into the flagellum or injectisome. In the flagellum, three of the EA proteins form an export gate core complex (FliPQR) and assemble into a helical structure that forms the start of the channel which culminates in the flagellum.

Research led by Steven Johnson and Lucas Kuhlen from Susan Lea’s lab was aimed at investigating the structure of the core export gate complex in the bacterial injectisome (SctRST). Single-particle cryo-electron microscopy of the export gate purified from human pathogen Shigella revealed a structure with striking similarity to the flagellar export complex gate. This finding further solidifies the conservation of the apparatus supporting the function of bacterial flagella and injectisomes.

Lucie Kafkova

Johnson S, Kuhlen L, Deme JC, Abrusci P, Lea SM.

mBio 10 (3) e00818-19; DOI: 10.1128/mBio.00818-19