Energy Requirements for Protein Secretion via the Flagellar Type III Secretion System

Part of the Methods in Molecular Biology book series (MIMB, volume 1615)


Protein transport across the cytoplasmic membrane is coupled to energy derived from adenosine triphosphate hydrolysis or the protein motive force (pmf). A sophisticated, multi-component type III secretion system exports substrate proteins of both the bacterial flagellum and virulence-associated injectisome system of many Gram-negative pathogens. The type-III secretion system is primarily a pmf-driven protein exporter. Here, I describe methods to investigate the export of substrate proteins into the culture supernatant under conditions that manipulate the pmf.

Key words

Type III secretion system Bacterial flagellum Protein export Proton motive force ∆pH gradient ∆Ψ gradient Ionophore Carbonyl cyanide m-chlorophenylhydrazone (CCCP) Valinomycin 



This work was supported by the Helmholtz Association young investigator grant VH-NG-932 and the People Programme (Marie Curie Actions) of the European Union Seventh Framework Programme (grant 334030).


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© Springer Science+Business Media LLC 2017

Authors and Affiliations

  1. 1.Helmholtz Centre for Infection ResearchBraunschweigGermany

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