The TATA-binding protein from Saccharomyces cerevisiae oligomerizes in solution at micromolar concentrations to form tetramers and octamers

Margaret A. Daugherty, Michael Brenowitz, Michael G. Fried

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Abstract

Equilibrium analytical ultracentrifugation has been used to determine the stoichiometry and energetics of the self-assembly of the TATA-binding protein of Saccharomyces cerevisiae at 30°C, in buffers ranging in salt concentration from 60 mM KCl to 1 M KCl. The data are consistent with a sequential association model in which monomers are in equilibrium with tetramers and octamers at protein concentrations above 2.6 μM. Association is highly cooperative, with octamer formation favored by ~7 kcal/mol over tetramers. At high [KCl], the concentration of tetramers becomes negligible and the data are best described by a monomer-octamer reaction mechanism. The equilibrium association constants for both monomer⇆tetramer and tetramer⇆octamer reactions change with [KCl] in a biphasic manner, decreasing with increasing [KCl] from 60 mM to 300 mM, and increasing with increasing [KCl] from 300 mM to 1 M. At low [KCl], ~3 mole equivalents of ions are released at each association step, while at high [KCl], ~3 mole equivalents of ions are taken up at each association step. These results suggest that there is a salt concentration-dependent change in the assembly mechanism, and that the mechanistic switch takes place near 300 mM KCl. The possibility that this self-association reaction may play a role in the activity of the TATA-binding protein in vivo is discussed.

Original languageEnglish (US)
Pages (from-to)1389-1399
Number of pages11
JournalJournal of Molecular Biology
Volume285
Issue number4
DOIs
Publication statusPublished - Jan 29 1999

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Keywords

  • Self-association
  • TBP
  • Thermodynamics

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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