Structural insights into Helicobacter pylori oncoprotein CagA interaction with β1 integrin
Burcu Kaplan-Türköz1, Luisa F Jiménez-Soto, Cyril Dian
1Centre National de la Recherche Scientifique-Ligue Contre le Cancer, ATIP Avenir Group, Institut de Biologie et Chimie des Protéines, Unité Mixte de Recherche 5086, Université Lyon, Lyon F-69367, France.
Summary
Helicobacter pylori infection can lead to gastric cancer. This study reveals the structure of the CagA protein, showing how it binds to host cells via β1 integrin to initiate cancer development.
Area of Science:
- Molecular Biology
- Cell Biology
- Structural Biology
Background:
- Helicobacter pylori infection is a major risk factor for gastric cancer.
- Pathogenic H. pylori strains inject the oncoprotein CagA into host cells using a type IV secretion system (T4SS).
- CagA injection hijacks host cell signaling and reorganizes the cytoskeleton, contributing to cancer development.
Purpose of the Study:
- To determine the crystal structure of the N-terminal CagA subdomain.
- To elucidate the mechanism by which CagA interacts with host cells.
- To identify potential interaction sites for protein-protein binding.
Main Methods:
- X-ray crystallography to determine the 3.6 Å structure of the CagA N-terminal subdomain.
- Sequence analysis to map conserved regions and identify putative interaction patches (CSP1-4).
- Yeast two-hybrid and in vivo competition assays to assess CagA-β1 integrin binding.
Main Results:
- The N-terminal CagA subdomain exhibits a unique fold with a core β-sheet and helical subdomains.
- Four conserved surface-exposed patches (CSP1-4) were identified as potential protein-protein interaction sites.
- The β1 integrin specifically binds to a proximal region of the β-sheet (CSP4), facilitating CagA translocation.
Conclusions:
- The study provides the first structural basis for CagA binding to β1 integrin, a critical step in CagA internalization.
- CagA utilizes a novel mechanism to bind β1 integrin, mediating its own translocation into host cells.
- Understanding this interaction offers insights into H. pylori-induced gastric carcinogenesis.
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