The MotA transcription factor from bacteriophage T4 contains a novel DNA-binding domain: the 'double wing' motif

Mol Microbiol. 2002 Mar;43(5):1079-88. doi: 10.1046/j.1365-2958.2002.02809.x.

Abstract

MotA is a transcription factor from bacteriophage T4 that helps adapt the host Escherichia coli transcription apparatus to T4 middle promoters. We have determined the crystal structure of the C-terminal DNA-binding domain of MotA (MotCF) to 1.6 A resolution using multiwavelength, anomalous diffraction methods. The structure reveals a novel DNA-binding alpha/beta motif that contains an exposed beta-sheet surface that mediates interactions with the DNA. Independent biochemical experiments have shown that MotCF binds to one surface of a single turn of DNA through interactions in adjacent major and minor grooves. We present a model of the interaction in which beta-ribbons at opposite corners of the six-stranded beta-sheet penetrate the DNA grooves, and call the motif a 'double wing' to emphasize similarities to the 'winged-helix' motif. The model is consistent with data on how MotA functions at middle promoters, and provides an explanation for why MotA can form non-specific multimers on DNA.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Bacteriophage T4 / chemistry*
  • Crystallography, X-Ray
  • DNA / metabolism
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Transcription Factors / chemistry*
  • Transcription Factors / metabolism
  • Viral Proteins / chemistry*
  • Viral Proteins / metabolism

Substances

  • DNA-Binding Proteins
  • MotA protein, Enterobacteria phage T4
  • Transcription Factors
  • Viral Proteins
  • DNA

Associated data

  • PDB/1KAF