Molecular dissection of protein-protein interactions between integrin α5β1 and the Helicobacter pylori Cag type IV secretion system.

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PubMed ID: 29055076

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Koelblen T, Bergé C, Cherrier MV, Brillet K, Jimenez-Soto L, Ballut L, Takagi J, Montserret R, Rousselle P, Fischer W, Haas R, Fronzes R, Terradot L

FEBS J. 12 2017. doi: 10.1111/febs.14299



The more severe strains of the bacterial human pathogen Helicobacter pylori produce a type IV secretion system (cagT4SS) to inject the oncoprotein cytotoxin-associated gene A (CagA) into gastric cells

 After translocation, CagA is tyrosine phosphorylated by host Src kinases and hijacks the signalling system of the cell. This leads to morphological changes in the cell and uncontrolled proliferation and provokes tumour development 

This syringe-like molecular apparatus is prolonged by an external pilus that exploits integrins as receptors to mediate the injection of CagA. The molecular determinants of the interaction of the cag T4SS pilus with the integrin ectodomain are still poorly understood

to generate a comprehensive analysis of the protein-protein interactions between purified CagA, CagL, CagI, CagY repeat domain II (CagYRRII), CagY C-terminal domain (CagYB10) and integrin alpha5beta1 ectodomain (alpha5beta1E) or headpiece domain (alfa5beta1HP)


The results show that the CagA, CagI, CagL and CagYB10 proteins interact with high affinity with integrin alfa5beta1E and that activation ofintegrin significantly increases the affinities of the Cag proteins/integrin interaction. Furthermore, the results confirm that the C-terminal part of CagA is not required for CagA interaction and the SLB domain interacts directly with integrin as previously proposed


This study and the methods described here pave the way to understand the exploitation of integrin by H. pylori and possibly other bacterial pathogens



Eduardo Pareja