PDBsum entry 1f20

Oxidoreductase

PDB id: 1f20

Contents

Protein chain

435 a.a. *

Ligands

FAD

NAP

GOL ×5

FMT ×3

Waters ×479

* Residue conservation analysis

PDB id:

1f20

Name:

Oxidoreductase

Title:

Crystal structure of rat neuronal nitric-oxide synthase fad/NADP+ domain at 1.9a resolution.

Structure:

Nitric-oxide synthase. Chain: a. Engineered: yes

Source:

Rattus norvegicus. Norway rat. Organism_taxid: 10116. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.90Å R-factor: 0.186 R-free: 0.206

Authors:

J.Zhang,P.Martasek,B.S.Masters,J.P.Kim

Key ref:

J.Zhang et al. (2001). Crystal structure of the FAD/NADPH-binding domain of rat neuronal nitric-oxide synthase. Comparisons with NADPH-cytochrome P450 oxidoreductase. J Biol Chem, 276, 37506-37513. PubMed id: 11473123 DOI: 10.1074/jbc.M105503200

Date:

22-May-00 Release date: 10-Oct-01

Protein chain

P29476  (NOS1_RAT) -  Nitric oxide synthase 1 from Rattus norvegicus

Seq: 1429 a.a.

Struc: 435 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.1.14.13.39 - nitric-oxide synthase (NADPH).
• Reaction: 2 L-arginine + 3 NADPH + 4 O2 + H⁺ = 2 L-citrulline + 2 nitric oxide + 3 NADP⁺ + 4 H2O

2 × L-arginine + 3 × NADPH + 4 × O2 (Bound ligand (Het Group name = NAP) corresponds exactly) + H(+) = 2 × L-citrulline + 2 × nitric oxide + 3 × NADP(+) + 4 × H2O

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1074/jbc.M105503200

J Biol Chem 276:37506-37513 (2001)

PubMed id: 11473123

Crystal structure of the FAD/NADPH-binding domain of rat neuronal nitric-oxide synthase. Comparisons with NADPH-cytochrome P450 oxidoreductase.

J.Zhang, P.Martàsek, R.Paschke, T.Shea, B.S.Siler Masters, J.J.Kim.

ABSTRACT

Nitric-oxide synthase (NOS) is composed of a C-terminal, flavin-containing reductase domain and an N-terminal, heme-containing oxidase domain. The reductase domain, similar to NADPH-cytochrome P450 reductase, can be further divided into two different flavin-containing domains: (a) the N terminus, FMN-containing portion, and (b) the C terminus FAD- and NADPH-binding portion. The crystal structure of the FAD/NADPH-containing domain of rat neuronal nitric-oxide synthase, complexed with NADP(+), has been determined at 1.9 A resolution. The protein is fully capable of reducing ferricyanide, using NADPH as the electron donor. The overall polypeptide fold of the domain is very similar to that of the corresponding module of NADPH-cytochrome P450 oxidoreductase (CYPOR) and consists of three structural subdomains (from N to C termini): (a) the connecting domain, (b) the FAD-binding domain, and (c) the NADPH-binding domain. A comparison of the structure of the neuronal NOS FAD/NADPH domain and CYPOR reveals the strict conservation of the flavin-binding site, including the tightly bound water molecules, the mode of NADP(+) binding, and the aromatic residue that lies at the re-face of the flavin ring, strongly suggesting that the hydride transfer mechanisms in the two enzymes are very similar. In contrast, the putative FMN domain-binding surface of the NOS protein is less positively charged than that of its CYPOR counterpart, indicating a different nature of interactions between the two flavin domains and a different mode of regulation in electron transfer between the two flavins involving the autoinhibitory element and the C-terminal 33 residues, both of which are absent in CYPOR.

Selected figure(s)

Figure 2.
Fig. 2. A stereo ribbon diagram of the nNOS-FAD/NBD structure. From N to C termini (bottom to top): the connecting domain is shown in red, the FAD domain is shown in green, and the NADPH domain is shown in blue. The cofactors, NADP+ and FAD, are shown with ball and sticks in red and yellow, respectively. Both N and C termini are also indicated. This figure was prepared with Molscript (34) and rendered with Raster3D (35).

Figure 5.
Fig. 5. Residues in the vicinity of the FAD isoalloxazine ring. The pyrimidine side of the FAD ring makes an extensive hydrogen bonding network with the main chain atoms (carbonyl oxygens of Thr1191 and Ala^1193 and the amide nitrogen of Ala^1193) of the polypeptide and two tightly bound water molecules, W1 and W2. The water molecule W2 might play a role of general acid/base in the protonation/deprotonation of the N1 atom of the flavin that is necessary during catalysis. The hydroxyl group of Ser1176 lies on the same plane as the FAD ring and is 3.7 Å away from the N5 atom of FAD. It also makes hydrogen bonds with Asp1393 and the O4 atom of the FAD ring. The carboxylate of Asp1393 makes a hydrogen bond with His1032 and is 3.7 Å away from the sulfhydryl group of Cys1349. Hydrogen bonds are indicated by thick dashed lines, and distances between 3.3 and 3.7 Å are indicated by thin dashed lines. The color scheme used is as follows: oxygen, dark gray; nitrogen, medium gray; and carbon, light gray.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2001, 276, 37506-37513) copyright 2001.

Figures were selected by an automated process.