CDI toxins are expressed by Gram-negative bacteria as part of a mechanism to inhibit the growth of neighbouring cells. This entry represents the inhibitor (CdiI, also called CdiI immunity protein) of the CdiA effector protein from Escherichia coli A0 34/86, and similar proteins. E.coli A0 CdiI adopts an alpha/beta structure consisting of a central antiparallel beta-sheet and alpha-helices packed on it PDB:5T86.

CDI toxins are expressed by Gram-negative bacteria as part of a mechanism to inhibit the growth of neighboring cells. This entry represents the inhibitor (CdiI, also called CdiI immunity protein) of the CdiA effector protein from Escherichia coli A0 34/86, and similar proteins.CdiA secretion is dependent on the outer membrane protein CdiB. Upon binding to a receptor on the surface of target bacteria, the CDI toxin is delivered via its C-terminal domain (CdiA-CT). The CdiI immunity proteins are intracellular proteins that inactivate the toxin/effector protein to prevent auto-inhibition. They are specific for their cognate CdiA-CT and do not protect cells from the toxins of other CDI bacteria. Thus, CDI systems encode a complex network of toxin-immunity protein pairs that are deployed for intercellular competition. This E. coli CdiI binds its cognate toxin CdiA-CT domain with high affinity . E.coli A0 CdiI adopts an α/β structure consisting of a central antiparallel β-sheet and helices packed on it ([pdbe:5T86]).