Open AccessImportance of Val567 on heme environment and substrate recognition of neuronal nitric oxide synthase
Author(s) -
Olsbu Inger K.,
Zoppellaro Giorgio,
Andersson K. Kristoffer,
Boucher JeanLuc,
Hersleth HansPetter
Publication year - 2018
Publication title -
febs open bio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.718
H-Index - 31
ISSN - 2211-5463
DOI - 10.1002/2211-5463.12503
Subject(s) - heme , nitric oxide , heme oxygenase , chemistry , nitric oxide synthase , active site , oxygenase , biochemistry , substrate (aquarium) , binding site , stereochemistry , mutant , biophysics , enzyme , biology , ecology , organic chemistry , gene
Nitric oxide ( NO ) produced by mammalian nitric oxide synthases ( mNOS s) is an important mediator in a variety of physiological functions. Crystal structures of mNOS s have shown strong conservation of the active‐site residue Val567 (numbering for rat neuronal NOS , nNOS ). NOS ‐like proteins have been identified in several bacterial pathogens, and these display striking sequence identity to the oxygenase domain of mNOS ( NOS oxy), with the exception of a Val to Ile mutation at the active site. Preliminary studies have highlighted the importance of this Val residue in NO ‐binding, substrate recognition, and oxidation in mNOS s. To further elucidate the role of this valine in substrate and substrate analogue recognition, we generated five Val567 mutants of the oxygenase domain of the neuronal NOS ( nNOS oxy) and used UV‐visible and EPR spectroscopy to investigate the effects of these mutations on the heme distal environment, the stability of the heme‐Fe II ‐ CO complexes, and the binding of a series of substrate analogues. Our results are consistent with Val567 playing an important role in preserving the integrity of the active site for substrate binding, stability of heme‐bound gaseous ligands, and potential NO production.