Helicobacter pylori is a bacterial pathogen that colonises the human stomach in half of the world’s population. The most virulent strains use the cag- type IV secretion system (cagT4SS), a molecular nanomachine capable of injecting the oncoprotein CagA into gastric cells. How CagA is delivered is unknown, but the cagT4SS apparatus contains several proteins that can interact with host cell receptors, mediating CagA translocation from the cytoplasm of the bacteria to the inner leaflet of the host cell membrane. CagI displays a unique dimeric structure and that its C-terminal domain is involved in interaction with the host cell. Designed Ankyrin Repeat Proteins were selected against CagI and found to interact with its C-terminal moiety with high affinity. DARPin binding was able to prevent CagI interaction with the host cell and inhibited CagA translocation by H. pylori. Here you can see a crystal structure of the structure of a CagI:K2 complex (PDB code: 8AK1)

#molecularart ... #immolecular ... #helicobacter ... #cagl ... #transport ... #antibiotic ... #inhibition ... #xray

Structure rendered with @proteinimaging and rendered with @corelphotopaint