Document 1140
 DOCN  M94A1140
 TI    Role of the thumb subdomain of HIV-1 reverse transcriptase analyzed by
       an inhibitory monoclonal antibody.
 DT    9412
 AU    Chiba J; Yamaguchi A; Wei Z; Ohba H; Saito A; Shinagawa H; Kurata T;
       Dept. of Bio. Sci. and Technol., Science Univ. of Tokyo, Japan.
 SO    Int Conf AIDS. 1994 Aug 7-12;10(2):20 (abstract no. 373A). Unique
       Identifier : AIDSLINE ICA10/94371435
 AB    OBJECTIVE: Recent crystallographic studies have provided a much more
       refined structure of HIV-1 reverse transcripase (RT) molecule. However,
       the organization of enzymatically active motifes or roles of each
       subdomain of the enzyme molecule is still not completely understood. We
       report here function of the epitope on HIV-1 RT molecule recognized by
       the 7C4 monoclonal antibody (7C4) which completely inhibits
       RNA-dependent DNA polymerase activity of RT. METHODS: Epitope mapping
       was carried out by testing reactivity of 7C4 either with various
       trancated RT molecules expressed in E. coli cells or with synthetic
       peptides of defined sequences from the HIV-1 pol gene. Kinetic
       measurements of the RNA-dependent DNA polymetase activity of RT were
       carried out using poly(rA) oligo(dT) as template/primer and dTTP as
       deoxynucleoside triphosphate substrate after incubation of the enzyme
       with varying concentrations of purified 7C4. RESULTS: Epitope mapping of
       7C4 revealed that the eptope existed on the thumb subdomain of RT
       molecule which had been determined by previous crystallographic
       analysis. Binding of equimolar 7C4 with RT resulted in complete
       inhibition of polymerase activity. The inhibition by Fab fragment of 7C4
       was competitive-type with respect to the template/primer and mixed-type
       with respect to the deoxynucleoside substrate. DISCUSSION AND
       CONCLUSION: The epitope on thumb subdomain of RT, which recognized by
       7C4 antibody, would be, or be closely located at, the template/primer
       binding site.
 DE    Antibodies, Monoclonal/*IMMUNOLOGY/PHARMACOLOGY  Antigenic
       Determinants/IMMUNOLOGY  Binding Sites  HIV-1/*ENZYMOLOGY/GENETICS
       Peptide Fragments/IMMUNOLOGY  *Protein Structure, Tertiary  Recombinant
       Fusion Proteins/IMMUNOLOGY  Reverse Transcriptase/ANTAGONISTS &
       INHIB/*CHEMISTRY/GENETICS/  IMMUNOLOGY  MEETING ABSTRACT

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