The central region of human T-cell leukemia virus type 1 Tax protein contains distinct domains involved in subunit dimerization.
The Tax protein of human T-cell leukemia virus type 1 (HTLV-1) can form homodimers. Tax dimerization contributes to optimal Tax activity involved in transactivation of the HTLV-1 promoter. The mechanisms used to form specific Tax dimers are poorly understood because the domains that mediate such interactions have not been clearly characterized. Here we have used different approaches (the two-hybrid assay in yeast, the glutathione S-transferase pull-down assay, and the Spot method) to study Tax-Tax interactions. Our results indicate that the integrity of the sequence of Tax, except for the last 16 amino acids (residues 338 to 353), is critical, suggesting that Tax dimerization is dictated more by secondary structure than by primary structure. We were, however, able to delimit a central region involved in Tax self-association that encompasses the residues 127 to 228. This region can be divided into three subdomains of dimerization: DD1 (residues 127 to 146), DD2 (residues 181 to 194), and DD3 (residues 213 to 228). Moreover, the Tax mutants M22 (T130A and L131S) and M29 (K189A and R190S), with amino acid substitutions located in DD1 and DD2, respectively, were found to be impaired in Tax self-association.
Basbous
Jihane
J
Laboratoire Infections Rétrovirales et Signalisation Cellulaire, CNRS/UM I UMR 5121/IFR 122, Institut de Biologie, 34960 Cedex 2, Montpellier, France.
Bazarbachi
Ali
A
Granier
Claude
C
Devaux
Christian
C
Mesnard
Jean-Michel
JM
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D016356:Gene Products, tax / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D015368:Human T-lymphotropic virus 1 / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques
D016356:Gene Products, tax; D010455:Peptides; D005982:Glutathione Transferase