title: Projection structure of a transcriptional regulator, HupR, determined by electron cryo-microscopy.
abstract: Large, well-ordered two-dimensional crystals of the histidine-tagged-HupR protein, a transcriptional regulator from the photosynthetic bacterium Rhodobacter capsulatus, were obtained by specific interaction with a Ni(2+)-chelated lipid monolayer. HupR is a response regulator of the NtrC subfamily; it activates the transcription of the structural genes hupSLC, of [NiFe]hydrogenase. A projection map of the full-length protein at 9 A resolution was obtained by electron cryo-microscopy and image analysis of frozen-hydrated two-dimensional crystals. The crystals have a p6 plane group with unit cell dimensions of a=b=111.6(+/-1.0) A, gamma=120.4(+/-0.5) degrees. The structure of the N-terminal domain of NtrC, the family to which HupR belongs, had been determined previously by NMR. The atomic coordinates of the N-terminal domain of NtrC, were compared to the structure obtained by cryo-electron microscope techniques of the whole HupR. These results provide the first structure at medium resolution of a whole transcription factor, HupR from the NtrC family.
authors.affiliation: Institut de Biologie Structurale Jean-Pierre Ebel (CEA-CNRS), 41 rue Jules Horowitz, Grenoble cedex 1, 38027, France. venien@biop.ox.ac.uk
authors.forename: C
authors.initials: C
authors.lastname: Vénien-Bryan
authors.forename: G F
authors.initials: GF
authors.lastname: Schertler
authors.forename: E
authors.initials: E
authors.lastname: Thouvenin
authors.forename: S
authors.initials: S
authors.lastname: Courty
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy; D003460:Crystallization; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000145:classification; D007091:Image Processing, Computer-Assisted; D050356:Lipid Metabolism; D008958:Models, Molecular; D009532:Nickel / Q000378:metabolism; D051922:PII Nitrogen Regulatory Proteins; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D016354:Rhodobacter capsulatus / Q000737:chemistry* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D015534:Trans-Activators; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D051922:PII Nitrogen Regulatory Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C070743:hupR1 protein, Rhodobacter capsulatus; D009532:Nickel