8UFP

Structure of human neuronal nitric oxide synthase R354A/G357D mutant heme domain in complex with 4-methyl-7-(4-methyl-2,3,4,5-tetrahydrobenzo[f][1,4]oxazepin-7-yl)quinolin-2-amine dihydrochloride

Summary for 8UFP

• Entry DOI: 10.2210/pdb8ufp/pdb
• Descriptor: Nitric oxide synthase, brain, PROTOPORPHYRIN IX CONTAINING FE, (7M)-4-methyl-7-(4-methyl-2,3,4,5-tetrahydro-1,4-benzoxazepin-7-yl)quinolin-2-amine, ... (6 entities in total)
• Functional Keywords: nitric oxide synthase inhibitor, heme enzyme, oxidoreductase
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 2
• Total formula weight: 100845.83

Authors

Li, H.,Poulos, T.L. (deposition date: 2023-10-04, release date: 2024-03-13, Last modification date: 2024-04-03)

Primary citation

Li, H.,Hardy, C.D.,Reidl, C.T.,Jing, Q.,Xue, F.,Cinelli, M.,Silverman, R.B.,Poulos, T.L.
Crystallographic and Computational Insights into Isoform-Selective Dynamics in Nitric Oxide Synthase.
Biochemistry, 63:788-796, 2024

PubMed Abstract: In our efforts to develop inhibitors selective for neuronal nitric oxide synthase (nNOS) over endothelial nitric oxide synthase (eNOS), we found that nNOS can undergo conformational changes in response to inhibitor binding that does not readily occur in eNOS. One change involves movement of a conserved tyrosine, which hydrogen bonds to one of the heme propionates, but in the presence of an inhibitor, changes conformation, enabling part of the inhibitor to hydrogen bond with the heme propionate. This movement does not occur as readily in eNOS and may account for the reason why these inhibitors bind more tightly to nNOS. A second structural change occurs upon the binding of a second inhibitor molecule to nNOS, displacing the pterin cofactor. Binding of this second site inhibitor requires structural changes at the dimer interface, which also occurs more readily in nNOS than in eNOS. Here, we used a combination of crystallography, mutagenesis, and computational methods to better understand the structural basis for these differences in NOS inhibitor binding. Computational results show that a conserved tyrosine near the primary inhibitor binding site is anchored more tightly in eNOS than in nNOS, allowing for less flexibility of this residue. We also find that the inefficiency of eNOS to bind a second inhibitor molecule is likely due to the tighter dimer interface in eNOS compared with nNOS. This study provides a better understanding of how subtle structural differences in NOS isoforms can result in substantial dynamic differences that can be exploited in the development of isoform-selective inhibitors.

PubMed: 38417024
DOI: 10.1021/acs.biochem.3c00601

Experimental method

X-RAY DIFFRACTION (1.9 Å)