An adenosine at position 27 in the human immunodeficiency virus type 1 trans-activation response element is not critical for transcriptional or translational activation by Tat.

AUTOR(ES)

Blanchard, A D

RESUMO

Tat protein binds to the trans-activation response (TAR) element of human immunodeficiency virus type 1 RNAs and activates gene expression at the level of transcription in mammalian cell lines and translation in Xenopus oocytes. Certain residues within TAR are important for Tat binding in vitro, including residue A-27, which appears to be able to be modified in a Tat-dependent manner in Xenopus oocytes (L. Sharmeen, B. Bass, N. Sonenberg, H. Weintraub, and M. Groudine, Proc. Natl. Acad. Sci. USA 88:8096-8100, 1991). Activation by Tat in oocytes occurs via a covalent modification of TAR-containing RNA. We have found that in both mammalian cells and Xenopus oocytes, conversion of A-27.U-38 or C-27.G-38 or C-27.G-38 reduces activation. However, conversion to G-27.U-38 or G-27.C-38 had little or no effect on activation, and in oocytes, these mutant RNAs were still covalently modified. These data exclude a specific role for the adenosine at residue 27 for Tat activation but suggest a requirement for a purine at this position.

Documentos Relacionados

• Unusual structure of the human immunodeficiency virus type 1 trans-activation response element.
• Functional analysis of interactions between Tat and the trans-activation response element of human immunodeficiency virus type 1 in cells.
• Bioassay for trans-activation using purified human immunodeficiency virus tat-encoded protein: trans-activation requires mRNA synthesis.
• The bend in RNA created by the trans-activation response element bulge of human immunodeficiency virus is straightened by arginine and by Tat-derived peptide.
• Inhibition of human immunodeficiency virus type 1 Tat-dependent activation of translation in Xenopus oocytes by the benzodiazepine Ro24-7429 requires trans-activation response element loop sequences.