The ion-channel forming colicins A, B, E1, Ia, Ib and N all kill bacterial cells selectively by co-opting bacterial active-transport pathways and forming voltage-gated ion conducting channels across the plasma membrane of the target bacterium. The crystal structure of colicin Ia reveals a molecule 210 A long with three distinct functional domains arranged along a backbone of two extraordinarily long alpha-helices. A central domain at the bend of the hairpin-like structure mediates specific recognition and binding to an outer-membrane receptor. A second domain mediates translocation across the outer membrane via the TonB transport pathway; the TonB-box recognition element of colicin Ia is on one side of three 80 A-long helices arranged as a helical sheet. A third domain is made up of 10 alpha-helices which form a voltage-activated and voltage-gated ion conducting channel across the plasma membrane of the target cell. The two 160 A-long alpha-helices that link the receptor-binding domain to the other domains enable the colicin Ia molecule to span the periplasmic space and contact both the outer and plasma membranes simultaneously during function.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|