Abstract
Heat-shock proteins (Hsp's) are a family of molecular chaperones that contribute to protection from environmental stress. In this report, we demonstrate that a member of this family, Hsp70, facilitates nuclear import of HIV-1 preintegration complexes (PICs). The mechanism of this activity appears to be similar to the one used by Vpr, an HIV-1 protein regulating viral nuclear import and replication in macrophages. Indeed Hsp70 stimulated binding of HIV-1 matrix antigen to GST-karyopherin alpha fusion protein and rescued nuclear import of a Vpr-defective HIV-1 strain in vitro. Binding studies with truncated forms of GST-karyopherin alpha demonstrated that both Vpr and Hsp70 bind to a region in the amino-terminal part of the karyopherin alpha molecule. This region appears to be distinct from the binding sites for two other karyopherin alpha cargoes, basic-type NLS-containing proteins and transcription factor STAT-1. Vpr competed with Hsp70 for binding to karyopherin alpha. These results suggest the presence of a novel regulatory site on karyopherin alpha which is used by Hsp70 and Vpr to stimulate interaction between the HIV-1 PIC and karyopherin alpha and thus promote viral nuclear import.
Copyright 2000 Academic Press.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Antigens, Polyomavirus Transforming / metabolism
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Binding Sites / physiology
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Binding, Competitive / physiology
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Biological Transport
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Cell Nucleus / metabolism
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Cell Nucleus / virology
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Cytosol / metabolism
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Cytosol / virology
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DNA-Binding Proteins / metabolism
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Gene Products, vpr / genetics
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Gene Products, vpr / metabolism*
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HIV Infections / metabolism*
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HIV Infections / virology*
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HIV-1 / genetics
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HIV-1 / growth & development
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HIV-1 / metabolism*
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HSP70 Heat-Shock Proteins / metabolism*
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HeLa Cells
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Humans
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Kidney / cytology
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Mutagenesis / physiology
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Nuclear Proteins / chemistry
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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STAT1 Transcription Factor
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Trans-Activators / metabolism
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Virus Integration / physiology*
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Virus Replication
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alpha Karyopherins
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vpr Gene Products, Human Immunodeficiency Virus
Substances
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Antigens, Polyomavirus Transforming
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DNA-Binding Proteins
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Gene Products, vpr
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HSP70 Heat-Shock Proteins
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Nuclear Proteins
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Recombinant Fusion Proteins
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STAT1 Transcription Factor
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STAT1 protein, human
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Trans-Activators
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alpha Karyopherins
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vpr Gene Products, Human Immunodeficiency Virus