Identification of a novel cell attachment domain in the HIV-1 Tat protein and its 90-kDa cell surface binding protein.
The HIV-1 transactivator protein Tat is essential for viral gene expression and replication. Tat is taken up by cells and transactivates the HIV-LTR promoter in the cell nucleus. The present studies show that cells adhere to both synthetic and recombinant Tat, and, using synthetic peptides, we localize the binding site to a region spanning amino acid residues 49-57 (peptide Tat49-57). Tat49-57 also inhibited cell attachment to solid phase full-length Tat peptide and to recombinant Tat protein. Using Tat peptide affinity chromatography, we identified a 90-kDa cell surface protein that binds to Tat. The 90-kDa protein could be eluted from the Tat column using the Tat49-57 peptide. A 90-kDa cell surface Tat binding protein was also identified by coprecipitation with Tat after incubation with radiolabeled cell membrane preparations. Co-precipitation of the 90-kDa protein was inhibited by competition with a Tat49-65 peptide, but not with Tat55-86. Our findings suggest that cellular attachment to Tat is mediated through a 90-kDa cell surface protein that binds to a Tat domain between amino acids 49 and 57.
Weeks
B S
BS
Laboratory of Developmental Biology, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Desai
K
K
Loewenstein
P M
PM
Klotman
M E
ME
Klotman
P E
PE
Green
M
M
Kleinman
H K
HK
D000595:Amino Acid Sequence; D000818:Animals; D001345:Autoradiography; D002448:Cell Adhesion; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D015696:Gene Products, tat / Q000737:chemistry / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D016716:PC12 Cells; D011485:Protein Binding; D051381:Rats; D015728:Receptors, HIV / Q000302:isolation & purification / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D008565:Membrane Proteins; D015728:Receptors, HIV; D054322:tat Gene Products, Human Immunodeficiency Virus