title: Crystal structure of the flavohemoglobin from Alcaligenes eutrophus at 1.75 A resolution.
abstract: The molecular structure of the flavohemoglobin from Alcaligenes eutrophus has been determined to a resolution of 1.75 A and refined to an R-factor of 19.6%. The protein comprises two fused modules: a heme binding module, which belongs to the globin family, and an FAD binding oxidoreductase module, which adopts a fold like ferredoxin reductase. The most striking deviation of the bacterial globin structure from those of other species is the movement of helix E in a way to provide more space in the vicinity of the distal heme binding site. A comparison with other members of the ferredoxin reductase family shows similar tertiary structures for the individual FAD and NAD binding domains but largely different interdomain orientations. The heme and FAD molecules approach each other to a minimal distance of 6.3 A and adopt an interplanar angle of 80 degrees. The electron transfer from FAD to heme occurs in a predominantly polar environment and may occur directly or be mediated by a water molecule.
authors.affiliation: Max-Planck-Institut fur Biophysik, Frankfurt, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Ermler
authors.forename: R A
authors.initials: RA
authors.lastname: Siddiqui
authors.forename: R
authors.initials: R
authors.lastname: Cramm
authors.forename: B
authors.initials: B
authors.lastname: Friedrich
mesh_terms: D000421:Alcaligenes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004579:Electron Transport; D005287:Ferredoxin-NADP Reductase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D005420:Flavoproteins / Q000737:chemistry; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D006420:Hemeproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009243:NAD / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D005420:Flavoproteins; D006420:Hemeproteins; C086193:flavohemoprotein, Bacteria; D009243:NAD; D005182:Flavin-Adenine Dinucleotide; D006418:Heme; D005287:Ferredoxin-NADP Reductase