PDBsum entry 1m7v

Oxidoreductase

PDB id: 1m7v

Contents

Protein chain

361 a.a. *

Ligands

ARG

HEM

THG

Waters ×258

* Residue conservation analysis

PDB id:

1m7v

Name:

Oxidoreductase

Title:

Structure of a nitric oxide synthase heme protein from bacillus subtilis with tetrahydrofolate and arginine bound

Structure:

Nitric oxide synthase. Chain: a. Engineered: yes

Source:

Bacillus subtilis. Organism_taxid: 1423. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PDB file)

Resolution:

1.95Å R-factor: 0.225 R-free: 0.239

Authors:

K.Pant,A.M.Bilwes,S.Adak,D.J.Stuehr,B.R.Crane

Key ref:

K.Pant et al. (2002). Structure of a nitric oxide synthase heme protein from Bacillus subtilis. Biochemistry, 41, 11071-11079. PubMed id: 12220171 DOI: 10.1021/bi0263715

Date:

22-Jul-02 Release date: 30-Oct-02

Protein chain

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

Seq: 363 a.a.

Struc: 361 a.a.*

* PDB and UniProt seqs differ at 17 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] + 2 × L-arginine (Bound ligand (Het Group name = ARG) corresponds exactly) + 4 × O2 = 3 × oxidized [flavodoxin] + 2 × L-citrulline + 2 × nitric oxide + 4 × H2O + 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/bi0263715

Biochemistry 41:11071-11079 (2002)

PubMed id: 12220171

Structure of a nitric oxide synthase heme protein from Bacillus subtilis.

K.Pant, A.M.Bilwes, S.Adak, D.J.Stuehr, B.R.Crane.

ABSTRACT

Eukaryotic nitric oxide synthases (NOSs) produce nitric oxide to mediate intercellular signaling and protect against pathogens. Recently, proteins homologous to mammalian NOS oxygenase domains have been found in prokaryotes and one from Bacillus subtilis (bsNOS) has been demonstrated to produce nitric oxide [Adak, S., Aulak, K. S., and Stuehr, D. J. (2002) J. Biol. Chem. 277, 16167-16171]. We present structures of bsNOS complexed with the active cofactor tetrahydrofolate and the substrate L-arginine (L-Arg) or the intermediate N(omega)-hydroxy-L-arginine (NHA) to 1.9 or 2.2 A resolution, respectively. The bsNOS structure is similar to those of the mammalian NOS oxygenase domains (mNOS(ox)) except for the absence of an N-terminal beta-hairpin hook and zinc-binding region that interact with pterin and stabilize the mNOS(ox) dimer. Changes in patterns of residue conservation between bacterial and mammalian NOSs correlate to different binding modes for pterin side chains. Residue conservation on a surface patch surrounding an exposed heme edge indicates a likely interaction site for reductase proteins in all NOSs. The heme pockets of bsNOS and mNOS(ox) recognize L-Arg and NHA similarly, although a change from Val to Ile beside the substrate guanidinium may explain the 10-20-fold slower dissociation of product NO from the bacterial enzyme. Overall, these structures suggest that bsNOS functions naturally to produce nitrogen oxides from L-Arg and NHA in a pterin-dependent manner, but that the regulation and purpose of NO production by NOS may be quite different in B. subtilis than in mammals.