The crystal structure of CCG1/TAF(II)250-interacting factor B (CIB)

J Biol Chem. 2004 Mar 5;279(10):9615-24. doi: 10.1074/jbc.M312165200. Epub 2003 Dec 11.


The general transcription initiation factor TFIID and its interactors play critical roles in regulating the transcription from both naked and chromatin DNA. We have isolated a novel TFIID interactor that we denoted as CCG1/TAF(II)250-interacting factor B (CIB). We show here that CIB activates transcription. To further understand the function of this protein, we determined its crystal structure at 2.2-Angstroms resolution. The tertiary structure of CIB reveals an alpha/beta-hydrolase fold that resembles structures in the prokaryotic alpha/beta-hydrolase family proteins. It is not similar in structure or primary sequence to any eukaryotic transcription or chromatin factors that have been reported to date. CIB possesses a conserved catalytic triad that is found in other alpha/beta-hydrolases, and our in vitro studies confirmed that it bears hydrolase activity. However, CIB differs from other alpha/beta-hydrolases in that it lacks a binding site excursion, which facilitates the substrate selectivity of the other alpha/beta-hydrolases. Further functional characterization of CIB based on its tertiary structure and through biochemical studies may provide novel insights into the mechanisms that regulate eukaryotic transcription.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Cycle Proteins / chemistry*
  • Cell Cycle Proteins / metabolism
  • Dimerization
  • Histone Acetyltransferases
  • Humans
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Conformation
  • Sequence Alignment
  • Structure-Activity Relationship
  • TATA-Binding Protein Associated Factors / chemistry*
  • TATA-Binding Protein Associated Factors / metabolism
  • Transcription Factor TFIID / chemistry*
  • Transcription Factor TFIID / metabolism


  • Cell Cycle Proteins
  • TATA-Binding Protein Associated Factors
  • Transcription Factor TFIID
  • Histone Acetyltransferases
  • TATA-binding protein associated factor 250 kDa

Associated data

  • PDB/1IMJ