title: Synthetic putative transmembrane region of minimal potassium channel protein (minK) adopts an alpha-helical conformation in phospholipid membranes.
abstract: Minimal potassium channel protein (minK) is a potassium channel protein consisting of 130 amino acids, possessing just one putative transmembrane domain. In this study we have synthesized a peptide with the amino acid sequence RDDSKLEALYILMVLGFFGFFTLGIMLSYI, containing the putative transmembrane region of minK, and analysed its secondary structure by using Fourier-transform IR and CD spectroscopy. The peptide was virtually insoluble in aqueous buffer, forming intermolecular beta-sheet aggregates. On attempted incorporation of the peptide into phospholipid membranes with a method involving dialysis, the peptide adopted a predominantly intermolecular beta-sheet conformation identical with that of the peptide in aqueous buffer, in agreement with a previous report [Horvàth, Heimburg, Kovachev, Findlay, Hideg and Marsh, (1995) Biochemistry 34, 3893-3898]. However, by using an alternative method of incorporating the peptide into phospholipid membranes we found that the peptide adopted a predominantly alpha-helical conformation, a finding consistent with various proposed structural models. These observed differences in secondary structure are due to artifacts of aggregation of the peptide before incorporation into lipid.
authors.affiliation: Department of Biochemistry and Molecular Biology, Royal Free Hospital School of Medicine, Rowland Hill Street, London NW3 2PF, U.K.
authors.forename: E A
authors.initials: EA
authors.lastname: Mercer
authors.forename: G W
authors.initials: GW
authors.lastname: Abbott
authors.forename: S P
authors.initials: SP
authors.lastname: Brazier
authors.forename: B
authors.initials: B
authors.lastname: Ramesh
authors.forename: P I
authors.initials: PI
authors.lastname: Haris
authors.forename: S K
authors.initials: SK
authors.lastname: Srai
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D008244:Lysophosphatidylcholines / Q000737:chemistry; D008563:Membrane Lipids / Q000737:chemistry*; D008567:Membranes, Artificial; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D015221:Potassium Channels / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D008244:Lysophosphatidylcholines; D008563:Membrane Lipids; D008567:Membranes, Artificial; D010446:Peptide Fragments; D010743:Phospholipids; D015221:Potassium Channels