title: Intrinsic curvature associated with the coordinately regulated anthrax toxin gene promoters.
abstract: The current model for virulence gene regulation in Bacillus anthracis involves several trans-acting factors, the most important of which appears to be the anthrax toxin activator encoded by the atxA gene. AtxA is a positive regulator of the toxin genes pagA, cya and lef, and of a number of other plasmid- and chromosome-encoded genes. The AtxA protein (56 kDa) possesses a predicted winged-helix DNA-binding domain and phosphotransferase system-regulated domains, but the mechanism for positive regulation of AtxA target genes is not known. Sequence similarities in the promoter regions of AtxA-regulated genes are not apparent, and recombinant AtxA binds DNA with a high affinity in a non-specific manner. We hypothesized that the toxin genes possess common structural features or cis-acting elements that are required for positive regulation. We employed deletion analyses to determine the minimal sequences required for atxA-mediated toxin gene expression. In silico modelling and in vitro experiments using double-stranded DNA corresponding to the toxin gene promoter regions indicated significant curvature associated with these regions. These findings suggest that the structural topology of the DNA plays an important role in the control of anthrax toxin gene expression.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas - Houston Health Science Center, 6431 Fannin St, Houston, TX 77030, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Hadjifrangiskou
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas - Houston Health Science Center, 6431 Fannin St, Houston, TX 77030, USA.
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Koehler
mesh_terms: D000942:Antigens, Bacterial / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D001408:Bacillus anthracis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D017384:Sequence Deletion; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
chemical_list: C082932:ATXA protein, Bacillus anthracis; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D015534:Trans-Activators; C030325:anthrax toxin