1cii
From Proteopedia
COLICIN IA
Structural highlights
Function[CEIA_ECOLX] This colicin is a channel-forming colicin. This class of transmembrane toxins depolarize the cytoplasmic membrane, leading to dissipation of cellular energy. Colicins are polypeptide toxins produced by and active against E.coli and closely related bacteria. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 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. Crystal structure of colicin Ia.,Wiener M, Freymann D, Ghosh P, Stroud RM Nature. 1997 Jan 30;385(6615):461-4. PMID:9009197[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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