H-1 AND N-15 RESONANCE ASSIGNMENTS OF OXIDIZED FLAVODOXIN FROM ANACYSTIS-NIDULANS WITH 3D NMR

Proton and nitrogen-15 sequence-specific nuclear magnetic resonance assignments have been determined for recombinant oxidized flavodoxin from Anacystis nidulans (169 residues, M(r) 19048). Assignments were obtained by using N-15-H-1 heteronuclear three-dimensional (3D) NMR spectroscopy on a uniformly nitrogen-15 enriched sample of the protein, pH 6.6, at 30-degrees-C. For 165 residues, the backbone and a large fraction of the side-chain proton resonances have been assigned. Medium- and long-range NOE's have been used to characterize the secondary structure. In solution, flavodoxin consists of a five-stranded parallel beta-sheet involving residues 3-9, 31-37, 49-56, 81-89, 114-117, and 141-144. Medium-range NOE's indicate the presence of several helices. Several N-15 and H-1 resonances of the flavin mononucleotide (FMN) prosthetic group have been assigned. The FMN-binding site has been investigated by using polypeptide-FMN NOE's.