Recognition of AT-rich DNA binding sites by the MogR repressor.
Publication Type:Journal Article
Source:Structure, Volume 17, Issue 5, p.769-77 (2009)
Keywords:AT Rich Sequence, Bacterial Proteins, Base Sequence, Binding Sites, DNA, DNA, Bacterial, Flagellin, Helix-Turn-Helix Motifs, Listeria monocytogenes, Models, Molecular, Molecular Sequence Data, Nucleic Acid Conformation, Promoter Regions, Genetic, Protein Conformation, Repressor Proteins
<p>The MogR transcriptional repressor of the intracellular pathogen Listeria monocytogenes recognizes AT-rich binding sites in promoters of flagellar genes to downregulate flagellar gene expression during infection. We describe here the 1.8 A resolution crystal structure of MogR bound to the recognition sequence 5' ATTTTTTAAAAAAAT 3' present within the flaA promoter region. Our structure shows that MogR binds as a dimer. Each half-site is recognized in the major groove by a helix-turn-helix motif and in the minor groove by a loop from the symmetry-related molecule, resulting in a "crossover" binding mode. This oversampling through minor groove interactions is important for specificity. The MogR binding site has structural features of A-tract DNA and is bent by approximately 52 degrees away from the dimer. The structure explains how MogR achieves binding specificity in the AT-rich genome of L. monocytogenes and explains the evolutionary conservation of A-tract sequence elements within promoter regions of MogR-regulated flagellar genes.</p>