Crystal Structure of the DNA-binding Domain of Mbp1, a Transcription Factor Important in Cell-Cycle Control of DNA Synthesis

Structure. 1997 Mar 15;5(3):349-58. doi: 10.1016/s0969-2126(97)00192-5.


Background: During the cell cycle, cells progress through four distinct phases, G1, S, G2 and M; transcriptional controls play an important role at the transition between these phases. MCB-binding factor (MBF), a transcription factor from budding yeast, binds to the so-called MCB (MluI cell-cycle box) elements found in the promoters of many DNA synthesis genes, and activates the transcription of those at the G1-->S phase transition. MBF is comprised of two proteins, Mbp1 and Swi6.

Results: The three-dimensional structure of the N-terminal DNA-binding domain of Mbp1 has been determined by multiwavelength anomalous diffraction from crystals of the selenomethionyl variant of the protein. The structure is composed of a six-stranded beta sheet interspersed with two pairs of alpha helices. The most conserved core region among Mbp1-related transcription factors folds into a central helix-turn-helix motif with a short N-terminal beta strand and a C-terminal beta hairpin.

Conclusions: Despite little sequence similarity, the structure within the core region of the Mbp1 N-terminal domain exhibits a similar fold to that of the DNA-binding domains of other proteins, such as hepatocyte nuclear factor-3gamma and histone H5 from eukaryotes, and the prokaryotic catabolite gene activator. However, the structure outside the core region defines Mbp1 as a larger entity with substructures that stabilize and display the helix-turn-helix motif.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Cell Cycle
  • Crystallography, X-Ray
  • DNA Replication / physiology*
  • DNA, Fungal / metabolism*
  • DNA-Binding Proteins / chemistry
  • Fungal Proteins / chemistry*
  • Fungal Proteins / metabolism
  • Helix-Turn-Helix Motifs
  • Hepatocyte Nuclear Factor 3-gamma
  • Models, Molecular
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry
  • Protein Binding
  • Protein Conformation*
  • Recombinant Fusion Proteins / chemistry
  • Saccharomyces cerevisiae / chemistry
  • Saccharomyces cerevisiae Proteins*
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Transcription Factors / chemistry*
  • Transcription Factors / metabolism


  • DNA, Fungal
  • DNA-Binding Proteins
  • Fungal Proteins
  • MBP1 protein, S cerevisiae
  • Nuclear Proteins
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Hepatocyte Nuclear Factor 3-gamma

Associated data