2D37

The Crystal Structure of Flavin Reductase HpaC complexed with NAD+

Summary for 2D37

• Entry DOI: 10.2210/pdb2d37/pdb
• Related: 2D36 2D38
• Descriptor: hypothetical NADH-dependent FMN oxidoreductase, FLAVIN MONONUCLEOTIDE, NICOTINAMIDE-ADENINE-DINUCLEOTIDE, ... (4 entities in total)
• Functional Keywords: flavin reductase, oxidoreductase
• Biological source: Sulfolobus tokodaii
• Total number of polymer chains: 1
• Total formula weight: 21276.91

Authors

Okai, M.,Kudo, N.,Lee, W.C.,Kamo, M.,Nagata, K.,Tanokura, M. (deposition date: 2005-09-26, release date: 2006-05-30, Last modification date: 2024-03-13)

Primary citation

Okai, M.,Kudo, N.,Lee, W.C.,Kamo, M.,Nagata, K.,Tanokura, M.
Crystal structures of the short-chain flavin reductase HpaC from Sulfolobus tokodaii strain 7 in its three states: NAD(P)(+)(-)free, NAD(+)(-)bound, and NADP(+)(-)bound
Biochemistry, 45:5103-5110, 2006

PubMed Abstract: 4-Hydroxyphenylacetate (4-HPA) is oxidized as an energy source by two component enzymes, the large component (HpaB) and the small component (HpaC). HpaB is a 4-HPA monooxygenase that utilizes FADH(2) supplied by a flavin reductase HpaC. We determined the crystal structure of HpaC (ST0723) from the aerobic thermoacidophilic crenarchaeon Sulfolobus tokodaii strain 7 in its three states [NAD(P)(+)-free, NAD(+)-bound, and NADP(+)-bound]. HpaC exists as a homodimer, and each monomer was found to contain an FMN. HpaC preferred FMN to FAD because there was not enough space to accommodate the AMP moiety of FAD in its flavin-binding site. The most striking difference between the NAD(P)(+)-free and the NAD(+)/NADP(+)-bound structures was observed in the N-terminal helix. The N-terminal helices in the NAD(+)/NADP(+)-bound structures rotated ca. 20 degrees relative to the NAD(P)(+)-free structure. The bound NAD(+) has a compact folded conformation with nearly parallel stacking rings of nicotinamide and adenine. The nicotinamide of NAD(+) stacked the isoalloxazine ring of FMN so that NADH could directly transfer hydride. The bound NADP(+) also had a compact conformation but was bound in a reverse direction, which was not suitable for hydride transfer.

PubMed: 16618099
DOI: 10.1021/bi052313i

Experimental method

X-RAY DIFFRACTION (1.7 Å)