C-terminal (CT) domain of the contact-dependent growth inhibition (CDI) system (CdiA-CT) protein CdiA of Escherichia coli A0 34/86, and similar proteins
CDI toxins are expressed by gram-negative bacteria as part of a mechanism to inhibit the growth of neighboring cells. 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 the C-terminal domain. A wide variety of C-terminal toxin domains appear to exist; this particular model contains the C-terminal (CT) domain Escherichia coli A0 34/86 CdiA. Activity of this E. coli CdiA-CT is as yet unknown. CDI(+) bacteria also produce a CDI immunity protein (CdiI) to specifically neutralize the CdiA-CT toxins to prevent auto-inhibition. This CdiA-CT binds its cognate CdiI with high affinity.