Transcriptional activation and self-association in yeast: protein-protein dimerization as a pleiotropic mechanism of HTLV-I Tax function.
The yeast one-hybrid and two-hybrid systems for the detection of protein-DNA and protein-protein interactions were used as an in vivo approach to investigate the functional characteristics of HTLV-1 Tax expressed in yeast. Tax, when targeted to the upstream activating sequence (UAS) via the DNA-binding domain of Gal4 (Gal4BD), was found to activate a minimal promoter in yeast, indicating the presence of a functionally intact activation domain. Using the two-hybrid assay in which Tax was fused to either Gal4BD or Gal4 activation domain (Gal4AD), we demonstrate that Tax self-associates in the nucleus of yeast cells. Mutational analysis was performed to delineate the functional domain(s) necessary for Tax-mediated trans-activation and self-association. Based on our results, we propose a pleiotropic mechanism in which Tax facilitates protein-protein dimerization of various cellular partners.
Jin
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DY
Molecular Virology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0460, USA.
Jeang
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D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D019281:Dimerization; D005656:Fungal Proteins / Q000096:biosynthesis / Q000378:metabolism; D016356:Gene Products, tax / Q000096:biosynthesis / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000502:physiology*; D006801:Humans; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D015533:Transcriptional Activation; D001616:beta-Galactosidase / Q000096:biosynthesis
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D016356:Gene Products, tax; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D001616:beta-Galactosidase