title: Crystal structure of the Vibrio cholerae quorum-sensing regulatory protein HapR.
abstract: Quorum sensing in Vibrio cholerae involves signaling between two-component sensor protein kinases and the response regulator LuxO to control the expression of the master regulator HapR. HapR, in turn, plays a central role in regulating a number of important processes, such as virulence gene expression and biofilm formation. We have determined the crystal structure of HapR to 2.2-A resolution. Its structure reveals a dimeric, two-domain molecule with an all-helical structure that is strongly conserved with members of the TetR family of transcriptional regulators. The N-terminal DNA-binding domain contains a helix-turn-helix DNA-binding motif and alteration of certain residues in this domain completely abolishes the ability of HapR to bind to DNA, alleviating repression of both virulence gene expression and biofilm formation. The C-terminal dimerization domain contains a unique solvent accessible tunnel connected to an amphipathic cavity, which by analogy with other TetR regulators, may serve as a binding pocket for an as-yet-unidentified ligand.
authors.affiliation: Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: Rukman S
authors.initials: RS
authors.lastname: De Silva
authors.forename: Gabriela
authors.initials: G
authors.lastname: Kovacikova
authors.forename: Wei
authors.initials: W
authors.lastname: Lin
authors.forename: Ronald K
authors.initials: RK
authors.lastname: Taylor
authors.forename: Karen
authors.initials: K
authors.lastname: Skorupski
authors.forename: F Jon
authors.initials: FJ
authors.lastname: Kull
mesh_terms: D000595:Amino Acid Sequence; D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000378:metabolism; D019281:Dimerization; D024202:Electrophoretic Mobility Shift Assay; D015870:Gene Expression; D017930:Genes, Reporter; D019077:Helix-Turn-Helix Motifs; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D053038:Quorum Sensing; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics; D016415:Sequence Alignment; D014734:Vibrio cholerae / Q000737:chemistry* / Q000235:genetics; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012097:Repressor Proteins; D001616:beta-Galactosidase