title: Mitochondrial type I nitric oxide synthase physically interacts with cytochrome c oxidase.
abstract: Nitric oxide (NO) regulates key aspects of cell metabolism through reversible inhibition of cytochrome c oxidase (CcOX), the terminal electron acceptor (complex IV) of the mitochondrial respiratory chain, in competition with oxygen. Recently, a constitutive mitochondrial NOS corresponding to a neuronal NOS-I isoform (mtNOS-I) has been identified in several tissues. The role of this enzyme might be to generate NO close enough to its target without a significant overall increase in cellular NO concentrations. An effective, selective, and specific NO action might be guaranteed further by a physical interaction between mtNOS-I and CcOX. This possibility has never been investigated. Here we demonstrate that mtNOS-I is associated with CcOX, as proven by electron microscopic immunolocalization and co-immunoprecipitation studies. By affinity chromatography, we found that association is due to physical interaction of mtNOS-I with the C-terminal peptide of the Va subunit of CcOX, which displays a consensus sequence for binding to the PDZ domain of mtNOS-I previously unreported for CcOX. The molecular details of the interaction have been analyzed by means of molecular modeling and molecular dynamics simulations. This is the first evidence of a protein-protein interaction mediated by PDZ domains involving CcOX.
authors.affiliation: Department of Biology-LIME, University ROMA TRE, Viale Guglielmo Marconi 446, 00146 Rome, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Persichini
authors.forename: Valeria
authors.initials: V
authors.lastname: Mazzone
authors.forename: Fabio
authors.initials: F
authors.lastname: Polticelli
authors.forename: Sandra
authors.initials: S
authors.lastname: Moreno
authors.forename: Giorgio
authors.initials: G
authors.lastname: Venturini
authors.forename: Emilio
authors.initials: E
authors.lastname: Clementi
authors.forename: Marco
authors.initials: M
authors.lastname: Colasanti
mesh_terms: D000818:Animals; D002525:Cerebellar Cortex / Q000378:metabolism* / Q000648:ultrastructure; D003198:Computer Simulation; D003576:Electron Transport Complex IV / Q000378:metabolism*; D005260:Female; D008297:Male; D051379:Mice; D008928:Mitochondria / Q000201:enzymology* / Q000648:ultrastructure; D008958:Models, Molecular; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000648:ultrastructure; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D019001:Nitric Oxide Synthase / Q000378:metabolism* / Q000648:ultrastructure; D052248:Nitric Oxide Synthase Type I; D011485:Protein Binding; D025941:Protein Interaction Mapping / Q000379:methods*; D014018:Tissue Distribution
chemical_list: D009419:Nerve Tissue Proteins; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496321:Nos1 protein, mouse; D003576:Electron Transport Complex IV