       Document 0902
 DOCN  M95A0902
 TI    Interaction of human immunodeficiency virus type 1 Tat-derived peptides
       with TAR RNA.
 DT    9510
 AU    Long KS; Crothers DM; Department of Chemistry, Yale University, New
       Haven, Connecticut; 06511, USA.
 SO    Biochemistry. 1995 Jul 11;34(27):8885-95. Unique Identifier : AIDSLINE
       MED/95337110
 AB    Basic peptides from the carboxy terminus of the human immunodeficiency
       virus type 1 (HIV-1) Tat protein bind to the stem-loop region of TAR
       RNA, spanning a trinucleotide bulge, with high affinity and moderate
       specificity. Previous studies have demonstrated that TAR RNA contains a
       specific arginine binding pocket. A series of 24 amino acid Tat-derived
       peptides with one or two arginines has been evaluated as possible
       structural models of the wild-type peptide in its interaction with TAR
       RNA, using gel electrophoretic methods and circular dichroism (CD)
       spectroscopy. Dissociation rate measurements indicate that these
       peptides form complexes with TAR RNA that are significantly less stable
       kinetically than the wild-type complex. Through a combination of
       dissociation and association rate measurements, we estimate that
       wild-type Tat peptide and TAR RNA interact with a Kd of about 16 pM.
       Together with competition experiments, these results confirm that band
       shift gel titration methods significantly underestimate absolute
       peptide-RNA binding affinities in the subnanomolar range. Through
       competition experiments with bulge mutants of TAR RNA, we demonstrate
       that peptides that form longer lived complexes with wild-type TAR RNA
       also show greater discrimination over TAR RNA bulge mutants. Difference
       CD spectra show that the Tat-derived peptides do not induce the same
       changes in TAR RNA as the wild-type peptide. The difference CD spectrum
       of argininamide bound to TAR RNA is most similar to that of the
       wild-type peptide-TAR RNA complex, implying that the differences in CD
       spectra upon complex formation are mostly due to changes in TAR RNA
       conformation.
 DE    Amino Acid Sequence  Base Sequence  Gene Products,
       tat/GENETICS/*METABOLISM  HIV Long Terminal Repeat/*GENETICS
       HIV-1/GENETICS/*METABOLISM  Kinetics  Molecular Sequence Data  Mutation
       Nucleic Acid Conformation  Peptide Fragments/CHEMISTRY/METABOLISM  RNA,
       Viral/CHEMISTRY/GENETICS/METABOLISM  Support, U.S. Gov't, P.H.S.
       Thermodynamics  JOURNAL ARTICLE

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

