The MotA transcription factor from bacteriophage T4 contains a novel DNA-binding domain: the 'double wing' motif.
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.
Li
Ning
N
Department of Structural Biology, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
Sickmier
E Allen
EA
Zhang
Rongguang
R
Joachimiak
Andrzej
A
White
Stephen W
SW
D000595:Amino Acid Sequence; D017122:Bacteriophage T4 / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism
D004268:DNA-Binding Proteins; C067996:MotA protein, Enterobacteria phage T4; D014157:Transcription Factors; D014764:Viral Proteins; D004247:DNA