Electrostatic interactions modulate the RNA-binding and transactivation specificities of the human immunodeficiency virus and simian immunodeficiency virus Tat proteins.
The transcriptional activating (Tat) proteins from human immunodeficiency virus and simian immunodeficiency virus are sequence-specific RNA-binding proteins. In human immunodeficiency virus Tat, a single arginine residue, flanked on each side by three to four basic amino acids, mediates specific binding to a bulge region in trans-acting responsive element (TAR) RNA. We have systematically mutated the flanking charged residues and found that, in addition to the position of the sequence-specific arginine, the particular arrangement of nonspecific electrostatic interactions is an important determinant of RNA-binding specificity and transactivation activity. These additional electrostatic contacts may help stabilize the structure of TAR RNA when bound to arginine. One critical electrostatic interaction, located two residues N-terminal to the arginine, is absent in the simian immunodeficiency virus Tat protein and accounts for the difference in promoter specificities of the human and simian immunodeficiency viral proteins.
Tao
J
J
Whitehead Institute for Biomedical Research, Cambridge, MA 02142.
Frankel
A D
AD
D000595:Amino Acid Sequence; D001665:Binding Sites; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D015696:Gene Products, tat / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006678:HIV / Q000235:genetics / Q000378:metabolism*; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D017433:Protein Structure, Secondary; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011994:Recombinant Proteins; D012091:Repetitive Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D054322:tat Gene Products, Human Immunodeficiency Virus; D015500:Chloramphenicol O-Acetyltransferase