Regulation of activity of the yeast TATA-binding protein through intra-molecular interactions.
Dimerization is proposed to be a regulatory mechanism for TATA-binding protein (TBP) activity both in vitro and in vivo. The reversible dimer-monomer transition of TBP is influenced by the buffer conditions in vitro. Using in vitro chemical cross-linking, we found yeast TBP (yTBP) to be largely monomeric in the presence of the divalent cation Mg2+, even at high salt concentrations. Apparent molecular mass of yTBP at high salt with Mg2+, run through a gel filtration column, was close to that of monomeric yTBP. Lowering the monovalent ionic concentration in the absence of Mg2+, resulted in dimerization of TBP. Effect of Mg2+ was seen at two different levels: at higher TBP concentrations, it suppressed the TBP dimerization and at lower TBP levels, it helped keep TBP monomers in active conformation (competent for binding TATA box), resulting in enhanced TBP-TATA complex formation in the presence of increasing Mg2+. At both the levels, activity of the full-length TBP in the presence of Mg2+ was like that reported for the truncated C-terminal domain of TBP from which the N-terminus is removed. Therefore for full-length TBP, intra-molecular interactions can regulate its activity via a similar mechanism.
Vanathi
Perumal
P
Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India.
Mishra
Anurag Kumar
AK
Bhargava
Purnima
P
D002850:Chromatography, Gel; D003432:Cross-Linking Reagents / Q000494:pharmacology; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D015966:Gene Expression Regulation, Fungal; D007477:Ions; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D016385:TATA Box; D035181:TATA-Box Binding Protein / Q000378:metabolism*
D003432:Cross-Linking Reagents; D007477:Ions; D035181:TATA-Box Binding Protein; D008274:Magnesium