title: Computational design of water-soluble analogues of the potassium channel KcsA.
abstract: Although the interiors of membrane and water-soluble proteins are similar in their physicochemical properties, membrane proteins differ in having larger fractions of hydrophobic residues on their exteriors. Thus, it should be possible to water-solubilize membrane proteins by mutating their lipid-contacting side chains to more polar groups. Here, a computational approach was used to generate water-soluble variants of the potassium channel KcsA. As a probe of the correctness of the fold, the proteins contain an agitoxin2 binding site from a mammalian homologue of the channel. The resulting proteins express in high yield in Escherichia coli and share the intended functional and structural properties with KcsA, including secondary structure, tetrameric quaternary structure, and tight specific binding to both agitoxin2 and a small molecule channel blocker.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Johnson Foundation, School of Medicine, Makineni Theoretical Laboratories, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Avram M
authors.initials: AM
authors.lastname: Slovic
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Kono
authors.forename: James D
authors.initials: JD
authors.lastname: Lear
authors.forename: Jeffery G
authors.initials: JG
authors.lastname: Saven
authors.forename: William F
authors.initials: WF
authors.lastname: DeGrado
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D003198:Computer Simulation; D003956:Dialysis; D004926:Escherichia coli; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015202:Protein Engineering; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D012995:Solubility; D012996:Solutions / Q000737:chemistry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D015221:Potassium Channels; D012996:Solutions; C107790:prokaryotic potassium channel; D014867:Water