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Mitochondrial type I nitric oxide synthase physically interacts with cytochrome c oxidase
Tiziana Persichini1, Valeria Mazzone, Fabio Polticelli
1Department of Biology-LIME, University ROMA TRE, Viale Guglielmo Marconi 446, 00146 Rome, Italy.
Neuroscience Letters
|June 1, 2005
Summary
Mitochondrial nitric oxide synthase (mtNOS-I) physically interacts with cytochrome c oxidase (CcOX). This protein-protein interaction, mediated by PDZ domains, precisely regulates cell metabolism by controlling CcOX activity.
Area of Science:
- Cellular metabolism
- Mitochondrial function
- Enzyme regulation
Background:
- Nitric oxide (NO) regulates cell metabolism by inhibiting cytochrome c oxidase (CcOX), the mitochondrial respiratory chain's complex IV.
- A constitutive neuronal nitric oxide synthase isoform (mtNOS-I) exists in mitochondria, potentially generating localized NO.
- The physical interaction between mtNOS-I and CcOX has not been previously investigated.
Purpose of the Study:
- To investigate the physical association between mitochondrial nitric oxide synthase (mtNOS-I) and cytochrome c oxidase (CcOX).
- To elucidate the molecular mechanism underlying the mtNOS-I and CcOX interaction.
Main Methods:
- Electron microscopic immunolocalization
- Co-immunoprecipitation studies
- Affinity chromatography
- Molecular modeling and dynamics simulations
Main Results:
- Demonstrated physical association between mtNOS-I and CcOX.
- Identified the interaction occurs via mtNOS-I's PDZ domain binding to the C-terminal peptide of CcOX subunit Va.
- Revealed a novel PDZ-mediated protein-protein interaction involving CcOX.
Conclusions:
- mtNOS-I is physically associated with CcOX within mitochondria.
- This interaction precisely targets CcOX, ensuring localized NO signaling for metabolic regulation.
- Provides the first evidence of a PDZ domain-mediated interaction involving CcOX.