scholarly journals Interplay between predicted inner-rod and gatekeeper in controlling substrate specificity of the type III secretion system

2013 ◽  
Vol 87 (6) ◽  
pp. 1183-1199 ◽  
Author(s):  
Youness Cherradi ◽  
Lionel Schiavolin ◽  
Simon Moussa ◽  
Alaeddine Meghraoui ◽  
Ahmed Meksem ◽  
...  
2003 ◽  
Vol 185 (7) ◽  
pp. 2259-2266 ◽  
Author(s):  
Petra J. Edqvist ◽  
Jan Olsson ◽  
Moa Lavander ◽  
Lena Sundberg ◽  
Åke Forsberg ◽  
...  

ABSTRACT Pathogenic Yersinia species use a type III secretion system to inhibit phagocytosis by eukaryotic cells. At 37°C, the secretion system is assembled, forming a needle-like structure on the bacterial cell surface. Upon eukaryotic cell contact, six effector proteins, called Yops, are translocated into the eukaryotic cell cytosol. Here, we show that a yscP mutant exports an increased amount of the needle component YscF to the bacterial cell surface but is unable to efficiently secrete effector Yops. Mutations in the cytoplasmic domain of the inner membrane protein YscU suppress the yscP phenotype by reducing the level of YscF secretion and increasing the level of Yop secretion. These results suggest that YscP and YscU coordinately regulate the substrate specificity of the Yersinia type III secretion system. Furthermore, we show that YscP and YscU act upstream of the cell contact sensor YopN as well as the inner gatekeeper LcrG in the pathway of substrate export regulation. These results further strengthen the strong evolutionary link between flagellar biosynthesis and type III synthesis.


2008 ◽  
Vol 190 (12) ◽  
pp. 4252-4262 ◽  
Author(s):  
Sarah E. Wood ◽  
Jin Jin ◽  
Scott A. Lloyd

ABSTRACT Pathogenic yersiniae utilize a type III secretion system to inject antihost factors, called Yops, directly into the cytosol of eukaryotic cells. The Yops are injected via a needle-like structure, comprising the YscF protein, on the bacterial surface. While the needle is being assembled, Yops cannot be secreted. YscP and YscU switch the substrate specificity of the secretion system to enable Yop export once the needle attains its proper length. Here, we demonstrate that the inner rod protein YscI plays a critical role in substrate specificity switching. We show that YscI is secreted by the type III secretion system and that YscI secretion by a yscP mutant is abnormally elevated. Furthermore, we show that mutations in the cytoplasmic domain of YscU reduce YscI secretion by the yscP null strain. We also demonstrate that mutants expressing one of three forms of YscI (those with mutations Q84A, L87A, and L96A) secrete substantial amounts of Yops yet exhibit severe defects in needle formation. In the absence of YscP, mutants with the same changes in YscI assemble needles but are unable to secrete Yops. Together, these results suggest that the formation of the inner rod, not the needle, is critical for substrate specificity switching and that YscP and YscU exert their effects on substrate export by controlling the secretion of YscI.


2008 ◽  
Vol 4 (6) ◽  
pp. e1000094 ◽  
Author(s):  
Christian Lorenz ◽  
Steve Schulz ◽  
Thomas Wolsch ◽  
Ombeline Rossier ◽  
Ulla Bonas ◽  
...  

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