title: Crystal structure determination of a flavoprotein FP390 from a luminescent bacterium, Photobacterium phosphoreum.
abstract: The three-dimensional structure of a flavoprotein, FP390, purified from a luminescent bacterium, Photobacterium phosphoreum, has been determined at 3 A resolution by X-ray crystallography. Crystallographic refinements of the structural model have led to an R-factor of 0.24 for the intensity data between 6 to 3 A resolution collected with synchrotron radiation. It was found that a homodimer of the FP390 molecules related by a non-crystallographic 2-fold axis is comprised in the asymmetric unit. Two homodimers are arranged around a crystallographic 2-fold axis to form a tetrameric assembly. The monomer molecule of FP390, to which two molecules of the flavin cofactor (Q-flavin) are bound, consists of a seven-stranded parallel beta-sheet which forms a half of the beta-barrel structure and seven alpha-helices which surround one side of the beta-barrel. We suggest that the reason why the Q-flavin sample prepared from FP390 is always a mixture of two components is connected with the fact that the monomer molecules has two flavin binding sites, at the dimer interface and at the molecular surface.
authors.affiliation: Research Laboratory of Resources Utilization, Tokyo Institute of Technology, Yokohama.
authors.forename: A
authors.initials: A
authors.lastname: Kita
authors.forename: S
authors.initials: S
authors.lastname: Kasai
authors.forename: K
authors.initials: K
authors.lastname: Miki
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D005420:Flavoproteins / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010776:Photobacterium / Q000737:chemistry*; D014965:X-Rays
chemical_list: D001426:Bacterial Proteins; D005420:Flavoproteins