PDBsum entry 1mjt

Oxidoreductase

PDB id: 1mjt

Contents

Protein chains

346 a.a. *

Ligands

GLC-FRU ×2

HEM ×2

NAD ×2

ITU ×2

Waters ×382

* Residue conservation analysis

References listed in PDB file

Key reference

• Title: Crystal structure of sanos, A bacterial nitric oxide synthase oxygenase protein from staphylococcus aureus.
• Authors: L.E.Bird, J.Ren, J.Zhang, N.Foxwell, A.R.Hawkins, I.G.Charles, D.K.Stammers.
• Ref.: Structure, 2002, 10, 1687-1696. [DOI no: 10.1016/S0969-2126(02)00911-5]
• PubMed id: 12467576

Abstract

Prokaryotic genes related to the oxygenase domain of mammalian nitric oxide synthases (NOSs) have recently been identified. Although they catalyze the same reaction as the eukaryotic NOS oxygenase domain, their biological function(s) are unknown. In order to explore rationally the biochemistry and evolution of the prokaryotic NOS family, we have determined the crystal structure of SANOS, from methicillin-resistant Staphylococcus aureus (MRSA), to 2.4 A. Haem and S-ethylisothiourea (SEITU) are bound at the SANOS active site, while the intersubunit site, occupied by the redox cofactor tetrahydrobiopterin (H(4)B) in mammalian NOSs, has NAD(+) bound in SANOS. In common with all bacterial NOSs, SANOS lacks the N-terminal extension responsible for stable dimerization in mammalian isoforms, but has alternative interactions to promote dimer formation.

Figure 3.
Figure 3. Detailed Structural Analysis of SANOS(A) Stereo diagram showing the dimer interface of SANOS. The main chains are shown as ribbons and coils, with the A chain colored green and the B chain colored blue. The side chains of key residues involved in the interface interactions are shown as balls and sticks and colored orange and cyan for the A and B chains, respectively. The yellow dashed lines represent the hydrogen bonds between the two chains. The four segments from each chain are labeled I-IV (residues 233-240, 259-280, 288-291, and 314-330, respectively).(B) Electrostatic surface (A chain) and ribbons (B chain) showing the charge distribution on the molecular surface and the dimer interface. The positively and negatively charged areas are colored blue and red, respectively. All ligands for both monomers are shown as dark yellow-colored space-filling representations. The side chains that are only conserved among bacterial NOSs are shown as balls and sticks, with the nitrogen and oxygen atoms colored in blue and red, respectively.(C) Stereo view of one set of ligand binding sites of SANOS. The main chain backbone of the A and B chains are colored dark and light gray, respectively. Haem, SEITU, and the nicotinamide and ribose moieties of NAD^+ are colored by atoms, with carbon atoms in dark gray. The haem iron is shown as a magenta sphere. The side chains of key residues are drawn as ball-and-stick representations and colored by atoms, with their carbon atoms in cyan. Water molecules are represented as red spheres. The broken yellow lines indicate hydrogen bonds between the substrates and the protein. SEITU, H[4]B, and a section of the hook from bovine eNOS that interacts with the pterin (colored orange) have been overlaid onto the SANOS interface ligand binding site.

The above figure is reprinted by permission from Cell Press: Structure (2002, 10, 1687-1696) copyright 2002.