PDBsum entry 4cx2

Oxidoreductase

PDB id: 4cx2

Contents

Protein chains

405 a.a.

Ligands

HEM ×2

H2B ×2

HW1 ×2

ACT ×4

Metals

_ZN

Waters ×483

PDB id:

4cx2

Name:

Oxidoreductase

Title:

Structure of bovine endothelial nitric oxide synthase heme domain in complex with 6-(5-(((3r,4r)-4-((6-amino-4-methylpyridin-2-yl)methyl) pyrrolidin-3-yl)oxy)pentyl)-4-methylpyridin-2-amine

Structure:

Nitric oxide synthase, endothelial. Chain: a, b. Fragment: heme domain, residues 40-482. Synonym: constitutive nos, cnos, ec-nos, endothelial nos, enos, nos type iii, nosiii, endothelial nitric oxide synthase. Engineered: yes. Mutation: yes

Source:

Bos taurus. Cattle. Organism_taxid: 9913. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

2.04Å R-factor: 0.164 R-free: 0.201

Authors:

H.Li,T.L.Poulos

Key ref:

H.Li et al. (2014). The mobility of a conserved tyrosine residue controls isoform-dependent enzyme-inhibitor interactions in nitric oxide synthases. Biochemistry, 53, 5272-5279. PubMed id: 25089924 DOI: 10.1021/bi500561h

Date:

03-Apr-14 Release date: 13-Aug-14

Protein chains

P29473  (NOS3_BOVIN) -  Nitric oxide synthase 3 from Bos taurus

Seq: 1205 a.a.

Struc: 405 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

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

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

reference

DOI no: 10.1021/bi500561h

Biochemistry 53:5272-5279 (2014)

PubMed id: 25089924

The mobility of a conserved tyrosine residue controls isoform-dependent enzyme-inhibitor interactions in nitric oxide synthases.

H.Li, J.Jamal, S.Delker, C.Plaza, H.Ji, Q.Jing, H.Huang, S.Kang, R.B.Silverman, T.L.Poulos.

ABSTRACT

Many pyrrolidine-based inhibitors highly selective for neuronal nitric oxide synthase (nNOS) over endothelial NOS (eNOS) exhibit dramatically different binding modes. In some cases, the inhibitor binds in a 180° flipped orientation in nNOS relative to eNOS. From the several crystal structures we have determined, we know that isoform selectivity correlates with the rotamer position of a conserved tyrosine residue that H-bonds with a heme propionate. In nNOS, this Tyr more readily adopts the out-rotamer conformation, while in eNOS, the Tyr tends to remain fixed in the original in-rotamer conformation. In the out-rotamer conformation, inhibitors are able to form better H-bonds with the protein and heme, thus increasing inhibitor potency. A segment of polypeptide that runs along the surface near the conserved Tyr has long been thought to be the reason for the difference in Tyr mobility. Although this segment is usually disordered in both eNOS and nNOS, sequence comparisons and modeling from a few structures show that this segment is structured quite differently in eNOS and nNOS. In this study, we have probed the importance of this surface segment near the Tyr by making a few mutants in the region followed by crystal structure determinations. In addition, because the segment near the conserved Tyr is highly ordered in iNOS, we also determined the structure of an iNOS-inhibitor complex. This new structure provides further insight into the critical role that mobility plays in isoform selectivity.