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M9640612.TXT
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1996-03-04
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Document 0612
DOCN M9640612
TI Vpr protein of human immunodeficiency virus type 1 forms
cation-selective channels in planar lipid bilayers.
DT 9604
AU Piller SC; Ewart GD; Premkumar A; Cox GB; Gage PW; John Curtin School of
Medical Research, Australian National; University, Canberra, Australia.
SO Proc Natl Acad Sci U S A. 1996 Jan 9;93(1):111-5. Unique Identifier :
AIDSLINE MED/96133887
AB A small (96-aa) protein, virus protein R (Vpr), of human
immunodeficiency virus type 1 contains one hydrophobic segment that
could form a membrane-spanning helix. Recombinant Vpr, expressed in
Escherichia coli and purified by affinity chromatography, formed ion
channels in planar lipid bilayers when it was added to the cis chamber
and when the trans chamber was held at a negative potential. The
channels were more permeable to Na+ than to Cl- ions and were inhibited
when the trans potential was made positive. Similar channel activity was
caused by Vpr that had a truncated C terminus, but the potential
dependence of channel activity was no longer seen. Antibody raised to a
peptide mimicking part of the C terminus of Vpr (AbC) inhibited channel
activity when added to the trans chamber but had no effect when added to
the cis chamber. Antibody to the N terminus of Vpr (AbN) increased
channel activity when added to the cis chamber but had no effect when
added to the trans chamber. The effects of potential and antibodies on
channel activity are consistent with a model in which the positive
C-terminal end of dipolar Vpr is induced to traverse the bilayer
membrane when the opposite (trans) side of the membrane is at a negative
potential. The C terminus of Vpr would then be available for interaction
with AbC in the trans chamber, and the N terminus would be available for
interaction with AbN in the cis chamber. The ability of Vpr to form ion
channels in vitro suggests that channel formation by Vpr in vivo is
possible and may be important in the life cycle of human
immunodeficiency virus type 1 and/or may cause changes in cells that
contribute to AIDS-related pathologies.
DE Amino Acid Sequence Base Sequence Computer Simulation DNA
Primers/CHEMISTRY Gene Products, vpr/*CHEMISTRY HIV-1/CHEMISTRY
Immunologic Techniques Ion Channel Gating Ion Channels/*CHEMISTRY
Lipid Bilayers Models, Molecular Molecular Sequence Data Recombinant
Proteins JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).