title: Structure of a monoclinic crystal from of cyctochrome b1 (Bacterioferritin) from E. coli.
abstract: Crystals of E. coli cytochrome b1, alias bacterioferritin, were grown fr om a low ionic strength solution. The resulting monoclniic P21 structure was solved by molecular replacement and refined using noncrystallographi c symmetries applied to the fundamental unit, consisting of two protein subunits and a single haem. From the Patterson self-rotation results it was shown that the asymmetric unit of the monoclinic crystal consists of 12 such dimers and corresponds to a complete, nearly spherical, molecule of bacterioferritin (M4 = 450 kDa) of 432 point-group symmetry. It is thus the most symmetrical cytochrome. As previously determined for the tetragonal form, the haem is located in a special position on a local twofold axis of the dimer. A bimetal centre is also observed within the four-helix bundle of each monomer; a metal-binding site is located on the fourfold axis.
authors.affiliation: Unité Biophysique Structurale, ERS133 CNRS, Université de Bordeaux 1, France.
authors.forename: A
authors.initials: A
authors.lastname: Dautant
authors.forename: J B
authors.initials: JB
authors.lastname: Meyer
authors.forename: J
authors.initials: J
authors.lastname: Yariv
authors.forename: G
authors.initials: G
authors.lastname: Précigoux
authors.forename: R M
authors.initials: RM
authors.lastname: Sweet
authors.forename: A J
authors.initials: AJ
authors.lastname: Kalb
authors.forename: F
authors.initials: F
authors.lastname: Frolow
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D003573:Cytochrome b Group / Q000737:chemistry*; D003625:Data Collection; D004926:Escherichia coli / Q000201:enzymology*; D005293:Ferritins / Q000737:chemistry*; D006418:Heme / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D003573:Cytochrome b Group; D006418:Heme; D005293:Ferritins; C018032:bacterioferritin