Document 0564
 DOCN  M9490564
 TI    Quantitative studies of the effect of HTLV-I Tax protein on CREB
       protein--DNA binding.
 DT    9411
 AU    Anderson MG; Dynan WS; Department of Chemistry and Biochemistry,
       University of Colorado,; Boulder 80309.
 SO    Nucleic Acids Res. 1994 Aug 11;22(15):3194-201. Unique Identifier :
       AIDSLINE MED/94344786
 AB    The human T-cell leukemia virus type I (HTLV-I) Tax protein increases
       the DNA binding activity of a number of different host cell
       transcription factors, including the cyclic AMP response element binding
       protein (CREB). We have performed quantitative studies of CREB binding
       in the presence and absence of Tax in an attempt to gain insight into
       the mechanism of the Tax effect. Enhancement of binding occurred over a
       wide range of CREB concentrations, but sharply increased at the lowest
       concentrations tested. The data are best explained by a two-step binding
       model where Tax changes the apparent equilibrium constants for both a
       CREB-CREB dimerization step and a (CREB)2-DNA binding step. We used the
       model to perform a quantitative analysis of the binding of CREB to DNA
       that had been mutated at positions flanking the core CREB recognition
       site. Results suggest that there are altered or more extensive
       DNA-protein contacts at these positions in the presence of Tax. We also
       used the model to analyze differences in the interaction of Tax with
       nonphosphorylated and protein kinase A-phosphorylated CREB protein.
       There was no significant change in the behavior of CREB upon
       phosphorylation.
 DE    Base Sequence  Binding Sites  Cyclic AMP-Dependent Protein
       Kinases/METABOLISM  DNA/CHEMISTRY/*METABOLISM  DNA-Binding Protein,
       Cyclic AMP-Responsive/CHEMISTRY/*METABOLISM  Escherichia coli  Gene
       Products, tax/*PHARMACOLOGY  Macromolecular Systems  Molecular Sequence
       Data  Phosphorylation  Recombinant Proteins/PHARMACOLOGY
       Structure-Activity Relationship  Support, Non-U.S. Gov't  Support, U.S.
       Gov't, Non-P.H.S.  JOURNAL ARTICLE

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