Basbous Jihane, Bazarbachi Ali, Granier Claude, Devaux Christian, Mesnard Jean-Michel
Laboratoire Infections Rétrovirales et Signalisation Cellulaire, CNRS/UM I UMR 5121/IFR 122, Institut de Biologie, 34960 Cedex 2, Montpellier, France.
J Virol. 2003 Dec;77(24):13028-35. doi: 10.1128/jvi.77.24.13028-13035.2003.
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.
人类嗜T淋巴细胞病毒1型(HTLV-1)的Tax蛋白可形成同二聚体。Tax二聚化有助于参与HTLV-1启动子反式激活的最佳Tax活性。由于介导这种相互作用的结构域尚未得到明确表征,因此形成特定Tax二聚体所采用的机制仍知之甚少。在这里,我们使用了不同的方法(酵母双杂交试验、谷胱甘肽S-转移酶下拉试验和斑点法)来研究Tax-Tax相互作用。我们的结果表明,除了最后16个氨基酸(残基338至353)外,Tax序列的完整性至关重要,这表明Tax二聚化更多地由二级结构而非一级结构决定。然而,我们能够划定一个参与Tax自缔合的中心区域,该区域包含残基127至228。该区域可分为三个二聚化亚结构域:DD1(残基127至146)、DD2(残基181至194)和DD3(残基213至228)。此外,分别位于DD1和DD2中的氨基酸取代的Tax突变体M22(T130A和L131S)和M29(K189A和R190S)在Tax自缔合中受损。