title: Structural determinants of DNA binding by a P. falciparum ApiAP2 transcriptional regulator.
abstract: Putative transcription factors have only recently been identified in the Plasmodium spp., with the major family of regulators comprising the Apicomplexan Apetala2 (AP2) proteins. To better understand the DNA-binding mechanisms of these transcriptional regulators, we characterized the structure and in vitro function of an AP2 DNA-binding domain from a prototypical Apicomplexan AP2 protein, PF14_0633 from Plasmodium falciparum. The X-ray crystal structure of the PF14_0633 AP2 domain bound to DNA reveals a beta-sheet fold that binds the DNA major groove through base-specific and backbone contacts; a prominent alpha-helix supports the beta-sheet structure. Substitution of predicted DNA-binding residues with alanine weakened or eliminated DNA binding in solution. In contrast to plant AP2 domains, the PF14_0633 AP2 domain dimerizes upon binding to DNA through a domain-swapping mechanism in which the alpha-helices of the AP2 domains pack against the beta-sheets of the dimer mates. DNA-induced dimerization of PF14_0633 may be important for tethering two distal DNA loci together in the nucleus and/or for inducing functional rearrangements of its domains to facilitate transcriptional regulation. Consistent with a multisite binding mode, at least two copies of the consensus sequence recognized by PF14_0633 are present upstream of a previously identified group of sporozoite-stage genes. Taken together, these findings illustrate how Plasmodium has adapted the AP2 DNA-binding domain for genome-wide transcriptional regulation.
authors.affiliation: Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, 550 Medical Sciences Center, 1300 University Avenue, Madison, WI 53706, USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Lindner
authors.forename: Erandi K
authors.initials: EK
authors.lastname: De Silva
authors.forename: James L
authors.initials: JL
authors.lastname: Keck
authors.forename: Manuel
authors.initials: M
authors.lastname: Llinás
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D017125:Genes, Protozoan; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D016054:DNA, Protozoan; D015800:Protozoan Proteins; D014157:Transcription Factors