title: Recognition of AT-rich DNA binding sites by the MogR repressor.
abstract: 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.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Aimee
authors.initials: A
authors.lastname: Shen
authors.forename: Darren E
authors.initials: DE
authors.lastname: Higgins
authors.forename: Daniel
authors.initials: D
authors.lastname: Panne
mesh_terms: D020856:AT Rich Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D005408:Flagellin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019077:Helix-Turn-Helix Motifs; D008089:Listeria monocytogenes / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012097:Repressor Proteins; D005408:Flagellin; C067138:flaA protein, bacteria; D004247:DNA