PMID:20878669

Citation	Komori, H, Seo, D, Sakurai, T and Higuchi, Y (2010) Crystal structure analysis of Bacillus subtilis ferredoxin-NADP(+) oxidoreductase and the structural basis for its substrate selectivity. Protein Sci. 19:2279-90
Abstract	Bacillus subtilis yumC encodes a novel type of ferredoxin-NADP+ oxidoreductase (FNR) with a primary sequence and oligomeric conformation distinct from those of previously known FNRs. In this study, the crystal structure of B. subtilis FNR (BsFNR) complexed with NADP+ has been determined. BsFNR features two distinct binding domains for FAD and NADPH in accordance with its structural similarity to Escherichia coli NADPH-thioredoxin reductase (TdR) and TdR-like protein from Thermus thermophilus HB8 (PDB code: 2ZBW). The deduced mode of NADP+ binding to the BsFNR molecule is nonproductive in that the nicotinamide and isoalloxazine rings are over 15 Å apart. A unique C-terminal extension, not found in E. coli TdR but in TdR-like protein from T. thermophilus HB8, covers the re-face of the isoalloxazine moiety of FAD. In particular, Tyr50 in the FAD-binding region and His324 in the C-terminal extension stack on the si- and re-faces of the isoalloxazine ring of FAD, respectively. Aromatic residues corresponding to Tyr50 and His324 are also found in the plastid-type FNR superfamily of enzymes, and the residue corresponding to His324 has been reported to be responsible for nucleotide specificity. In contrast to the plastid-type FNRs, replacement of His324 with Phe or Ser had little effect on the specificity or reactivity of BsFNR with NAD(P)H, whereas replacement of Arg190, which interacts with the 2'-phosphate of NADP+, drastically decreased its affinity toward NADPH. This implies that BsFNR adopts the same nucleotide binding mode as the TdR enzyme family and that aromatic residue on the re-face of FAD is hardly relevant to the nucleotide selectivity.
Links	PubMed PMC3009396 Online version:10.1002/pro.508
Keywords	Amino Acid Sequence; Bacillus subtilis/enzymology; Crystallography, X-Ray; Ferredoxin-NADP Reductase/chemistry; Ferredoxin-NADP Reductase/metabolism; Molecular Sequence Data; Protein Structure, Secondary; Sequence Homology, Amino Acid; Structure-Activity Relationship; Substrate Specificity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BACSU:FENR2		GO:0055114: oxidation-reduction process	ECO:0000314:		P		NADPH-binding domain must rotate 60° relative to the FAD-binding domain in order for hydride (movement of electrons and protons) transfer to take place as seen as figure 2d.	complete CACAO 4770
BACSU:FENR2	Contributes to	GO:0004324: ferredoxin-NADP+ reductase activity	ECO:0000314:		F		Figure 2: Showsstructure of the BsFNR monomer in complex with NADP+ (Form I). FAD- and NAD(P)H-binding domains are shown in green and lightgreen. FAD is in yellow and NADP+ in blue. Overall structure of the BsFNR dimer in complex with NADP+.	complete
BACSU:FENR2	Contributes to	GO:0004324 : ferredoxin-NADP+ reductase activity	ECO:0000315:		F		Figure 2: Showsstructure of the BsFNR monomer in complex with NADP+ (Form I). FAD- and NAD(P)H-binding domains are shown in green and lightgreen. FAD is in yellow and NADP+ in blue. Overall structure of the BsFNR dimer in complex with NADP+.	complete

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