PDBsum entry 2fc2

Oxidoreductase

PDB id: 2fc2

Contents

Protein chains

362 a.a. *

Ligands

HEM-_NO

HBI ×2

HAR ×2

_NO ×2

HEM

Waters ×699

* Residue conservation analysis

PDB id:

2fc2

Name:

Oxidoreductase

Title:

No-heme complex in a bacterial nitric oxide synthase. An fe(iii)-no may cause nitrosation.

Structure:

Nitric oxide synthase. Chain: a, b. Engineered: yes

Source:

Bacillus subtilis. Organism_taxid: 1423. Expressed in: escherichia coli. Expression_system_taxid: 562

Biol. unit:

Dimer (from PDB file)

Resolution:

2.20Å R-factor: 0.259 R-free: 0.274

Authors:

K.Pant,B.R.Crane

Key ref:

K.Pant and B.R.Crane (2006). Nitrosyl-heme structures of Bacillus subtilis nitric oxide synthase have implications for understanding substrate oxidation. Biochemistry, 45, 2537-2544. PubMed id: 16489746 DOI: 10.1021/bi0518848

Date:

10-Dec-05 Release date: 22-Aug-06

Protein chains

O34453  (NOSO_BACSU) -  Nitric oxide synthase oxygenase from Bacillus subtilis (strain 168)

Seq: 363 a.a.

Struc: 363 a.a.*

* PDB and UniProt seqs differ at 15 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.1.14.14.47 - nitric-oxide synthase (flavodoxin).
• Reaction: 3 reduced [flavodoxin] + 2 L-arginine + 4 O2 = 3 oxidized [flavodoxin] + 2 L-citrulline + 2 nitric oxide + 4 H2O + 5 H⁺

3 × reduced [flavodoxin] (Bound ligand (Het Group name = HAR) matches with 92.31% similarity) + 2 × L-arginine + 4 × O2 = 3 × oxidized [flavodoxin] + 2 × L-citrulline + 2 × nitric oxide + 4 × H2O (Bound ligand (Het Group name = NO) corresponds exactly) + 5 × H(+)

• Cofactor: 5,6,7,8-tetrahydrobiopterin; Ferriheme b

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

reference

DOI no: 10.1021/bi0518848

Biochemistry 45:2537-2544 (2006)

PubMed id: 16489746

Nitrosyl-heme structures of Bacillus subtilis nitric oxide synthase have implications for understanding substrate oxidation.

K.Pant, B.R.Crane.

ABSTRACT

The crystal structures of nitrosyl-heme complexes of a prokaryotic nitric oxide synthase (NOS) from Bacillus subtilis (bsNOS) reveal changes in active-site hydrogen bonding in the presence of the intermediate N(omega)-hydroxy-l-arginine (NOHA) compared to the substrate l-arginine (l-Arg). Correlating with a Val-to-Ile residue substitution in the bsNOS heme pocket, the Fe(II)-NO complex with both l-Arg and NOHA is more bent than the Fe(II)-NO, l-Arg complex of mammalian eNOS [Li, H., Raman, C. S., Martasek, P., Masters, B. S. S., and Poulos, T. L. (2001) Biochemistry 40, 5399-5406]. Structures of the Fe(III)-NO complex with NOHA show a nearly linear nitrosyl group, and in one subunit, partial nitrosation of bound NOHA. In the Fe(II)-NO complexes, the protonated NOHA N(omega) atom forms a short hydrogen bond with the heme-coordinated NO nitrogen, but active-site water molecules are out of hydrogen bonding range with the distal NO oxygen. In contrast, the l-Arg guanidinium interacts more weakly and equally with both NO atoms, and an active-site water molecule hydrogen bonds to the distal NO oxygen. This difference in hydrogen bonding to the nitrosyl group by the two substrates indicates that interactions provided by NOHA may preferentially stabilize an electrophilic peroxo-heme intermediate in the second step of NOS catalysis.