       Document 0650
 DOCN  M9640650
 TI    Human immunodeficiency virus type 1 integrase mutants retain in vitro
       integrase activity yet fail to integrate viral DNA efficiently during
       infection.
 DT    9604
 AU    Leavitt AD; Robles G; Alesandro N; Varmus HE; Department of Laboratory
       Medicine, University of California, San; Francisco 94143-0100, USA.
 SO    J Virol. 1996 Feb;70(2):721-8. Unique Identifier : AIDSLINE MED/96135179
 AB    The viral integrase (IN) protein is the only viral protein known to be
       required for integration of the human immunodeficiency virus type 1
       (HIV-1) genome into the host cell DNA, a step in the viral life cycle
       that is essential for viral replication. To better understand the
       relationship between in vitro IN activity and IN-mediated integration of
       viral DNA in an infected cell, we characterized the effects of 13 IN
       mutations on viral replication in cultured cells. Using HIV-1 genomes
       that express the hygromycin resistance gene and do not express the HIV-1
       env gene, we generated stocks of pseudotype virus coated with the murine
       leukemia virus amphotropic envelope glycoprotein, containing either
       wild-type or mutant HIV-1 IN. All mutants produced normal amounts of
       physical particles, as measured by reverse transcriptase activity and
       capsid protein (p24) concentration, but they formed three groups based
       on infectious titer and synthesis of viral DNA. Changes at the three
       highly conserved acidic residues in the IN core domain (D-64, D-116, and
       E-152) impair provirus formation without affecting viral DNA synthesis
       or the accumulation of viral DNA in the nucleus of the infected cell, a
       phenotype predicted by each mutant's lack of in vitro integrase
       activity. Mutations at positions N-120, R-199, and W-235 minimally
       affect in vitro integrase activity, but infectious titers are severely
       reduced, despite normal synthesis of viral DNA, implying a defect during
       integration in vivo. Mutations in the zinc binding region (H12C, H16V,
       and H16C), S81R, and a deletion of residues 32 through 275 yield
       noninfectious particles that synthesize little or no viral DNA following
       infection, despite wild-type levels of reverse transcriptase activity
       and viral RNA in the particles. The two latter classes of mutants
       suggest that IN can affect DNA synthesis or integration during infection
       in ways that are not appreciated from currently used assays in vitro.
 DE    Animal  Binding Sites  Cell Line  Cell Nucleus/METABOLISM  DNA
       Nucleotidyltransferases/GENETICS/*METABOLISM  DNA, Viral/*METABOLISM
       Human  HIV-1/*ENZYMOLOGY/GENETICS  Point Mutation  Proviruses/METABOLISM
       Structure-Activity Relationship  Support, Non-U.S. Gov't  Support, U.S.
       Gov't, P.H.S.  Tumor Cells, Cultured  Viral Proteins/METABOLISM
       Virion/METABOLISM  Virus Integration/GENETICS/*PHYSIOLOGY  JOURNAL
       ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

