Mutational analysis of human T-cell leukemia virus type I Tax: regions necessary for function determined with 47 mutant proteins

J Virol. 1992 Dec;66(12):7183-92. doi: 10.1128/JVI.66.12.7183-7192.1992.


We have made 47 mutations that span the length of the human T-cell leukemia virus type I (HTLV-I) Tax open reading frame. Of the 47 mutations, 38 were substitutions of single amino acids, 5 were missense changes in two or more amino acids, and 4 were deletions. A subset of these mutations includes individual changes of all 26 naturally occurring serines to alanines. By assaying each mutant protein separately on the HTLV-I long terminal repeat (LTR) and the human immunodeficiency virus type 1 (HIV-1) LTR in parallel, we were able to identify regions of Tax selectively necessary for each promoter. A small region in the carboxyl terminus, amino acids 315 to 325, was found to be selectively important for activation of the HTLV-I LTR. Three changes at serine 113, serine 160, and serine 258 were found to specifically affect function on the HIV-1 LTR. Surprisingly, we found that the great preponderance of missense changes (32 of 42) in Tax did not affect function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • DNA, Viral / genetics
  • DNA, Viral / metabolism
  • Fluorescent Antibody Technique
  • Gene Products, tax / analysis
  • Gene Products, tax / genetics
  • Gene Products, tax / metabolism*
  • Genes, pX*
  • HIV Long Terminal Repeat
  • Human T-lymphotropic virus 1 / genetics*
  • Human T-lymphotropic virus 1 / metabolism*
  • Mutagenesis, Site-Directed*
  • Repetitive Sequences, Nucleic Acid
  • Sequence Deletion
  • Subcellular Fractions / metabolism
  • Transcriptional Activation
  • Transfection


  • DNA, Viral
  • Gene Products, tax