PMID: 11918797 , Related PDB id: 1KAF

Authors:

Li N, Sickmier EA, Zhang R, Joachimiak A, White SW

Title:

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

Journal:

Mol Microbiol. 2002 Mar;43(5):1079-88.

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.