1ahn

File:1ahn.gif

spinqualitylabelsall models 1ahn, resolution 2.6Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

E. COLI FLAVODOXIN AT 2.6 ANGSTROMS RESOLUTION

OverviewOverview

In Escherichia coli, flavodoxin is the physiological electron donor for, the reductive activation of the enzymes pyruvate formate-lyase, anaerobic, ribonucleotide reductase, and B12-dependent methionine synthase. As a, basis for studies of the interactions of flavodoxin with methionine, synthase, crystal structures of orthorhombic and trigonal forms of, oxidized recombinant flavodoxin from E. coli have been determined. The, orthorhombic form (space group P2(1)2(1)2(1), a = 126.4, b = 41.10, c =, 69.15 A, with two molecules per asymmetric unit) was solved initially by, molecular replacement at a resolution of 3.0 A, using coordinates from the, structure of the flavodoxin from Synechococcus PCC 7942 (Anacystis, nidulans). Data extending to 1.8-A resolution were collected at 140 K and, the structure was refined to an Rwork of 0.196 and an Rfree of 0.250 for, reflections with I > 0. The final model contains 3,224 non-hydrogen atoms, per asymmetric unit, including 62 flavin mononucleotide (FMN) atoms, 354, water molecules, four calcium ions, four sodium ions, two chloride ions, and two Bis-Tris buffer molecules. The structure of the protein in the, trigonal form (space group P312, a = 78.83, c = 52.07 A) was solved by, molecular replacement using the coordinates from the orthorhombic, structure, and was refined with all data from 10.0 to 2.6 A (R = 0.191;, Rfree = 0.249). The sequence Tyr 58-Tyr 59, in a bend near the FMN, has so, far been found only in the flavodoxins from E. coli and Haemophilus, influenzae, and may be important in interactions of flavodoxin with its, partners in activation reactions. The tyrosine residues in this bend are, influenced by intermolecular contacts and adopt different orientations in, the two crystal forms. Structural comparisons with flavodoxins from, Synechococcus PCC 7942 and Anaebaena PCC 7120 suggest other residues that, may also be critical for recognition by methionine synthase.

About this StructureAbout this Structure

1AHN is a Single protein structure of sequence from Escherichia coli with CA and FMN as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.

ReferenceReference

A flavodoxin that is required for enzyme activation: the structure of oxidized flavodoxin from Escherichia coli at 1.8 A resolution., Hoover DM, Ludwig ML, Protein Sci. 1997 Dec;6(12):2525-37. PMID:9416602

Page seeded by OCA on Tue Dec 18 14:15:13 2007