       Document 0252
 DOCN  M9620252
 TI    The orientation of binding of human immunodeficiency virus reverse
       transcriptase on nucleic acid hybrids.
 DT    9602
 AU    DeStefano JJ; Department of Microbiology, University of Maryland,
       College Park; 20742, USA.
 SO    Nucleic Acids Res. 1995 Oct 11;23(19):3901-8. Unique Identifier :
       AIDSLINE MED/96038846
 AB    The binding of HIV reverse transcriptase (RT) to heteroduplexes was
       examined using a substrate consisting of a 42 nt chimeric nucleic acid
       composed. (5'-->3') of 23 nt of RNA and 19 of DNA. This chimera was
       hybridized to an internal region of a relatively long complementary DNA
       or RNA. When the chimera was bound to DNA and conditions limiting
       cleavage to a single binding event between the enzyme and substrate were
       employed initial RNase H-directed cleavages occurred 19-21 nt from the
       chimera 5'-terminus. A 42 nt strand identical in sequence to the chimera
       and composed of only RNA was cleaved at the same locations. Reducing the
       length of the DNA portion of the chimera from 19 to 7 nt did not alter
       the cleavage positions, suggesting that cleavage was not coordinated by
       the DNA 3'-terminus. Under the same conditions cleavage was not detected
       when the chimera was bound to RNA. In contrast, addition of dNTPs to the
       DNA 3'-terminus of the chimera occurred only when the chimera was bound
       to RNA. The results support preferable binding of RT to RNA-DNA versus
       DNA-DNA hybrid regions and a model in which the orientation of binding
       to heteroduplexes is 5'-->3' (relative to the RNA strand), polymerase to
       RNase H active site, with sites associated with the DNA and RNA strand
       respectively.
 DE    Base Sequence  Binding Sites  DNA, Complementary/CHEMISTRY/METABOLISM
       Heparin/PHARMACOLOGY  HIV/*ENZYMOLOGY  Molecular Sequence Data  Nucleic
       Acid Heteroduplexes/CHEMISTRY/*METABOLISM  Nucleic Acid Hybridization
       Recombinant Proteins/METABOLISM  Ribonuclease H, Calf Thymus/METABOLISM
       RNA-Directed DNA Polymerase/*METABOLISM  RNA,
       Complementary/CHEMISTRY/METABOLISM  Structure-Activity Relationship
       Support, U.S. Gov't, P.H.S.  JOURNAL ARTICLE

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

