Anchored plasticity opens doors for selective inhibitor design in nitric oxide synthase.
Nitric oxide synthase (NOS) enzymes synthesize nitric oxide, a signal for vasodilatation and neurotransmission at low concentrations and a defensive cytotoxin at higher concentrations. The high active site conservation among all three NOS isozymes hinders the design of selective NOS inhibitors to treat inflammation, arthritis, stroke, septic shock and cancer. Our crystal structures and mutagenesis results identified an isozyme-specific induced-fit binding mode linking a cascade of conformational changes to a new specificity pocket. Plasticity of an isozyme-specific triad of distant second- and third-shell residues modulates conformational changes of invariant first-shell residues to determine inhibitor selectivity. To design potent and selective NOS inhibitors, we developed the anchored plasticity approach: anchor an inhibitor core in a conserved binding pocket, then extend rigid bulky substituents toward remote specificity pockets, which become accessible upon conformational changes of flexible residues. This approach exemplifies general principles for the design of selective enzyme inhibitors that overcome strong active site conservation.
Garcin
Elsa D
ED
The Scripps Research Institute, Department of Molecular Biology and Skaggs Institute for Chemical Biology, 10550 North Torrey Pines Road, MB4, La Jolla, California 92037, USA. egarcin@umbc.edu
Arvai
Andrew S
AS
Rosenfeld
Robin J
RJ
Kroeger
Matt D
MD
Crane
Brian R
BR
Andersson
Gunilla
G
Andrews
Glen
G
Hamley
Peter J
PJ
Mallinder
Philip R
PR
Nicholls
David J
DJ
St-Gallay
Stephen A
SA
Tinker
Alan C
AC
Gensmantel
Nigel P
NP
Mete
Antonio
A
Cheshire
David R
DR
Connolly
Stephen
S
Stuehr
Dennis J
DJ
Aberg
Anders
A
Wallace
Alan V
AV
Tainer
John A
JA
Getzoff
Elizabeth D
ED
D000595:Amino Acid Sequence; D000631:Aminopyridines / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D018360:Crystallography, X-Ray; D004195:Disease Models, Animal; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D007249:Inflammation / Q000188:drug therapy* / Q000201:enzymology*; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D008297:Male; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011799:Quinazolines / Q000737:chemistry / Q000494:pharmacology; D051381:Rats
D000631:Aminopyridines; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D011799:Quinazolines; D019001:Nitric Oxide Synthase