The tat gene of human immunodeficiency virus type 1 (HIV-l), essential for viral replication, is involved in transactivation of HIV-1 LTR-directed gene expression. To date, the molecular mechanisms by which the Tat protein interacts with the HIV-1 LTR appears to be unique to HIV-1 and some closely related lentiviruses. The long term goal of the research in this proposal is to understand the mechanism of action of Tat and, therefore, contribute to the rational design of methods for interfering with Tat function.
The specific aims of this proposal are: 1. To express wild type and mutant Tat proteins in cell-free systems and investigate structural features important for activity. 2. To express wild type and mutant Tat proteins from an adenovirus vector and identify cellular proteins that bind to Tat during the process of transactivation. 3. To construct mutant HIV-2 Tat proteins and chimeras between HIV-1 and HIV-2 Tat proteins and analyze similarities, as well as differences, between these related, but biologically disstinct, proteins. We will use the knowledge obtained from experiments dealing with these specific aims to attempt to devise methods of blockdng Tat activity and, therefore, HIV-1 replication in tissue culture. Practical synthetic approaches to several new """"""""purine-like"""""""" C-Nucleosides are described. These substances are structurally related to several new purine nucleoside antimetabolites synthesized recently in our laboratory, among others, the 9-deazapurine C-nucleosides and their thieno[3,2-d] and furo[3,2-d] pyrimidine congeners which have exhibited a wide spectrum of useful biological activity. The rationales offered are based on: a) the demonstrated anticancer, anti- trypanosomal and antileishmanial activity of several members of the 9-deazapurine C-nucleosides and their thieno and furo congeners and b) their potential use as biochemical probes as specific inhibitors of key purine metabolism enzymes. It is suggested that the candidates may possess chemotherapeutic properties similar to those of the lead compounds. Biological studies for the proper antitumor evaluations of all target C- nucleosides are described. Other collaborative studies would help evaluate their antiprotozoal properties and inhibitory activities against Purine Nucleoside Phosphorylase and Methylthio Adenosine Phosphorylase. Relationships between chemical structures and biological activity should be ascertainable from these investigations.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI025308-05
Application #
3138752
Study Section
AIDS and Related Research Study Section 3 (ARRC)
Project Start
1987-09-30
Project End
1995-11-30
Budget Start
1991-12-01
Budget End
1992-11-30
Support Year
5
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Baylor College of Medicine
Department
Type
Schools of Medicine
DUNS #
074615394
City
Houston
State
TX
Country
United States
Zip Code
77030
Yang, X; Herrmann, C H; Rice, A P (1996) The human immunodeficiency virus Tat proteins specifically associate with TAK in vivo and require the carboxyl-terminal domain of RNA polymerase II for function. J Virol 70:4576-84
Herrmann, C H; Gold, M O; Rice, A P (1996) Viral transactivators specifically target distinct cellular protein kinases that phosphorylate the RNA polymerase II C-terminal domain. Nucleic Acids Res 24:501-8
Herrmann, C H; Rice, A P (1995) Lentivirus Tat proteins specifically associate with a cellular protein kinase, TAK, that hyperphosphorylates the carboxyl-terminal domain of the large subunit of RNA polymerase II: candidate for a Tat cofactor. J Virol 69:1612-20
Rhim, H; Rice, A P (1995) HIV-1 Tat protein is able to efficiently transactivate the HIV-2 LTR through a TAR RNA element lacking both dinucleotide bulge binding sites. Virology 206:673-8
Echetebu, C O; Rhim, H; Herrmann, C H et al. (1994) Construction and characterization of a potent HIV-2 Tat transdominant mutant protein. J Acquir Immune Defic Syndr 7:655-64
Rhim, H; Rice, A P (1994) Functional significance of the dinucleotide bulge in stem-loop1 and stem-loop2 of HIV-2 TAR RNA. Virology 202:202-11
Rhim, H; Rice, A P (1994) Exon2 of HIV-2 Tat contributes to transactivation of the HIV-2 LTR by increasing binding affinity to HIV-2 TAR RNA. Nucleic Acids Res 22:4405-13
Rhim, H; Echetebu, C O; Herrmann, C H et al. (1994) Wild-type and mutant HIV-1 and HIV-2 Tat proteins expressed in Escherichia coli as fusions with glutathione S-transferase. J Acquir Immune Defic Syndr 7:1116-21
Herrmann, C H; Rice, A P (1993) Specific interaction of the human immunodeficiency virus Tat proteins with a cellular protein kinase. Virology 197:601-8
Rice, A P; Wilson, E; Chan, F (1993) Limited proteolytic digestions identify common structural features of HIV-1 Tat proteins expressed during infection from alternatively spliced mRNAs. J Acquir Immune Defic Syndr 6:344-52

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