title: Structure of transcription factor HetR required for heterocyst differentiation in cyanobacteria.
abstract: HetR is an essential regulator of heterocyst development in cyanobacteria. HetR binds to a DNA palindrome upstream of the hetP gene. We report the crystal structure of HetR from Fischerella at 3.0 Å. The protein is a dimer comprised of a central DNA-binding unit containing the N-terminal regions of the two subunits organized with two helix-turn-helix motifs; two globular flaps extending in opposite directions; and a hood over the central core formed from the C-terminal subdomains. The flaps and hood have no structural precedent in the protein database, therefore representing new folds. The structural assignments are supported by site-directed mutagenesis and DNA-binding studies. We suggest that HetR serves as a scaffold for assembly of transcription components critical for heterocyst development.
authors.affiliation: Midwest Center for Structural Genomics and Structural Biology Center, Biosciences, Argonne National Laboratory, 9700 South Cass Avenue, Building 202, Argonne, IL 60439, USA.
authors.forename: Youngchang
authors.initials: Y
authors.lastname: Kim
authors.forename: Grazyna
authors.initials: G
authors.lastname: Joachimiak
authors.forename: Zi
authors.initials: Z
authors.lastname: Ye
authors.forename: T Andrew
authors.initials: TA
authors.lastname: Binkowski
authors.forename: Rongguang
authors.initials: R
authors.lastname: Zhang
authors.forename: Piotr
authors.initials: P
authors.lastname: Gornicki
authors.forename: Sean M
authors.initials: SM
authors.lastname: Callahan
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Hess
authors.forename: Robert
authors.initials: R
authors.lastname: Haselkorn
authors.forename: Andrzej
authors.initials: A
authors.lastname: Joachimiak
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D000458:Cyanobacteria / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D004269:DNA, Bacterial / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D014157:Transcription Factors; C067403:HetR protein, Bacteria