ATPase-independent type-III protein secretion in Salmonella enterica.
Type-III protein secretion systems are utilized by gram-negative pathogens to secrete building blocks of the bacterial flagellum, virulence effectors from the cytoplasm into host cells, and structural subunits of the needle complex. The flagellar type-III secretion apparatus utilizes both the energy of the proton motive force and ATP hydrolysis to energize substrate unfolding and translocation. We report formation of functional flagella in the absence of type-III ATPase activity by mutations that increased the proton motive force and flagellar substrate levels. We additionally show that increased proton motive force bypassed the requirement of the Salmonella pathogenicity island 1 virulence-associated type-III ATPase for secretion. Our data support a role for type-III ATPases in enhancing secretion efficiency under limited secretion substrate concentrations and reveal the dispensability of ATPase activity in the type-III protein export process.
Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany.
Marc
M
Erhardt
Department of Biology, University of Utah, Salt Lake City, Utah, United States of America.
Max E
ME
Mertens
Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany.
Florian D
FD
Fabiani
Department of Biology, University of Utah, Salt Lake City, Utah, United States of America.
Kelly T
KT
Hughes
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D005407:Flagella / Q000235:genetics*; D044404:Genomic Islands / Q000235:genetics; D009154:Mutation; D018892:Proton-Motive Force; D019779:Salmonella enterica / Q000235:genetics* / Q000472:pathogenicity; D037521:Virulence Factors / Q000235:genetics*
D037521:Virulence Factors; D000251:Adenosine Triphosphatases