An Amino-Acid Substitution in the Influenza-B NB Protein Affects Ion-Channel Gating
Date
2004
Authors
Premkumar, Anita
Ewart, Gary
Cox, Graeme
Gage, Peter
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
The effects of site-directed mutations in NB, a protein encoded by the influenza B virus that has been shown to form cation-selective ion channels at pH 6.0, were studied on ion channel characteristics in artificial lipid bilayers. It was thought that the residues in the hydrophobic region of NB we selected for mutation might be involved in the transport of cations across the channel and that changes in these residues might affect channel properties such as gating and ion-selectivity. Serine residues at positions 20 and 28, threonine at position 24 and cysteine at position 26 were replaced by alanine. We found that the mutation S20A gave channels that did not gate and that remained open most of the time. Proton permeability of NB channels, as detected by fluorescence quenching, was also altered by the mutation S20A: channels were no longer proton-permeable. The other mutations, S28A, T24A and C26A, did not have any detectable effect on the activity or proton permeability of channels formed by NB. The results indicate that serine 20 may have an important role in normal function of NB channels.
Description
Keywords
Keywords: alanine; cation; cysteine; ion channel; serine; threonine; unclassified drug; virus nb protein; virus protein; amino acid substitution; animal cell; article; channel gating; controlled study; fluorescence; gene mutation; hydrophobicity; Influenza virus B; Amino acid substitution; Influenza-B; Ion channel gating; NB protein; Transmembrane domain
Citation
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Source
Journal of Membrane Biology
Type
Journal article