title: Biophysical characterization of Vpu from HIV-1 suggests a channel-pore dualism.
abstract: Vpu from HIV-1 is an 81 amino acid type I integral membrane protein which consists of a cytoplasmic and a transmembrane (TM) domain. The TM domain is known to alter membrane permeability for ions and substrates when inserted into artificial membranes. Peptides corresponding to the TM domain of Vpu (Vpu(1-32)) and mutant peptides (Vpu(1-32)-W23L, Vpu(1-32)-R31V, Vpu(1-32)-S24L) have been synthesized and reconstituted into artificial lipid bilayers. All peptides show channel activity with a main conductance level of around 20 pS. Vpu(1-32)-W23L has a considerable flickering pattern in the recordings and longer open times than Vpu(1-32). Whilst recordings for Vpu(1-32)-R31V are almost indistinguishable from those of the WT peptide, recordings for Vpu(1-32)-S24L do not exhibit any noticeable channel activity. Recordings of WT peptide and Vpu(1-32)-W23L indicate Michaelis-Menten behavior when the salt concentration is increased. Both peptide channels follow the Eisenman series I, indicative for a weak ion channel with almost pore like characteristics.
authors.affiliation: Biomembrane Structure Unit, Department of Biochemistry, Oxford University, Oxford OX1 3QU, United Kingdom.
authors.forename: T
authors.initials: T
authors.lastname: Mehnert
authors.forename: A
authors.initials: A
authors.lastname: Routh
authors.forename: P J
authors.initials: PJ
authors.lastname: Judge
authors.forename: Y H
authors.initials: YH
authors.lastname: Lam
authors.forename: D
authors.initials: D
authors.lastname: Fischer
authors.forename: A
authors.initials: A
authors.lastname: Watts
authors.forename: W B
authors.initials: WB
authors.lastname: Fischer
mesh_terms: D054298:Human Immunodeficiency Virus Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D006801:Humans; D007473:Ion Channels; D007700:Kinetics; D008051:Lipid Bilayers / Q000378:metabolism*; D009994:Osmolar Concentration; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics; D054334:Viral Regulatory and Accessory Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D000086082:Viroporin Proteins
chemical_list: D054298:Human Immunodeficiency Virus Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; D010446:Peptide Fragments; D054334:Viral Regulatory and Accessory Proteins; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins