Epitopes described in "Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution."

Article Authors:Y Zhou; J H Morais-Cabral; A Kaufman; R MacKinnon
Article Title:Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution.
Reference Detail
Reference ID:1001553
Abstract:Ion transport proteins must remove an ion's hydration shell to coordinate the ion selectively on the basis of its size and charge. To discover how the K+ channel solves this fundamental aspect of ion conduction, we solved the structure of the KcsA K+ channel in complex with a monoclonal Fab antibody fragment at 2.0 A resolution. Here we show how the K+ channel displaces water molecules around an ion at its extracellular entryway, and how it holds a K+ ion in a square antiprism of water molecules in a cavity near its intracellular entryway. Carbonyl oxygen atoms within the selectivity filter form a very similar square antiprism around each K+ binding site, as if to mimic the waters of hydration. The selectivity filter changes its ion coordination structure in low K+ solutions. This structural change is crucial to the operation of the selectivity filter in the cellular context, where the K+ ion concentration near the selectivity filter varies in response to channel gating.
Reference Type:Literature
PubMed ID:11689936
Journal Volume:414
Article Pages:43-8
Journal ISSN:1476-4687
Article Chemical List:Antibodies, Monoclonal;Bacterial Proteins;Immunoglobulin Fab Fragments;Potassium Channels;Solutions;prokaryotic potassium channel;Water;Potassium
Article MeSH List:Animals; Antibodies, Monoclonal(chemistry; immunology; metabolism); Bacterial Proteins; Crystallography, X-Ray; Electrochemistry; Immunoglobulin Fab Fragments(chemistry; immunology; metabolism); Mice; Models, Biological; Models, Molecular; Particle Size; Potassium(chemistry; metabolism); Potassium Channels(chemistry; immunology; metabolism); Protein Conformation; Solutions; Water(chemistry)
Curation Last Updated:2014-10-03 20:03:27