Cited by 389Neutrophil, Myeloperoxidase and Oxidative MechanismsRedox biology and oxidative stressNitric Oxide and Endothelin Effects

Mechanism of Ca2+ Activation of the NADPH Oxidase 5 (NOX5)

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Bánfi, Botond, Tirone, Fabiana, Durussel, Isabelle, Knisz, Judit, Moskwa, Patryk, Molnár, Gergely Zoltán, Krause, Karl-Heinz, Cox, Jos A.·2004·Journal of Biological Chemistry

Abstract

NADPH oxidase 5 (NOX5) is a homologue of the gp91(phox) subunit of the phagocyte NADPH oxidase. NOX5 is expressed in lymphoid organs and testis and distinguished from the other NADPH oxidases by its unique N terminus, which contains three canonical EF-hands, Ca(2+)-binding domains. Upon heterologous expression, NOX5 was shown to generate superoxide in response to intracellular Ca(2+) elevations. In this study, we have analyzed the mechanism of Ca(2+) activation of NOX5. In a cell-free system, Ca(2+) elevations triggered superoxide production by NOX5 (K(m) = 1.06 microm) in an NADPH- and FAD-dependent but cytosol-independent manner. That result indicated a role for the N-terminal EF-hands in NOX5 activation. Therefore, we generated recombinant proteins of NOX5 N terminus and investigated their interactions with Ca(2+). Flow dialysis experiments showed that NOX5 N terminus contained four Ca(2+)-binding sites and allowed us to define the hitherto unidentified fourth, non-canonical EF-hand. The EF-hands of NOX5 formed two pairs: the very N-terminal pair had relatively low affinity for Ca(2+), whereas the more C-terminal pair bound Ca(2+) with high affinity. Ca(2+) binding caused a marked conformation change in the N terminus, which exposed its hydrophobic core, and became able to bind melittin, a model peptide for calmodulin targets. Using a pull-down assay, we demonstrate that the regulatory N terminus and the catalytic C terminus of NOX5 interact in a Ca(2+)-dependent way. Our results indicate that the Ca(2+)-induced conformation change of NOX5 N terminus led to enzyme activation through an intra-molecular interaction. That represents a novel mechanism of activation among NAD(P)H oxidases and Ca(2+)-activated enzymes.

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Crossref · 10.1074/jbc.m310268200

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Authors
Bánfi, B., Tirone, F., Durussel, I., Knisz, J., Moskwa, P., Molnár, G. Z., Krause, K.-H., & Cox, J. A.
Affiliations
  • University of Geneva (CH)
  • University Hospital of Geneva (CH)
  • Semmelweis University (HU)
Corresponding author
Cox, Jos A.
Venue
Journal of Biological Chemistry
Publisher
Elsevier BV
Published
2004-04
Volume
279
Issue
18
Pages
18583-18591
ISSN
0021-9258 (ISSN-L)
OpenAlex
W2105940831
Cited by
389
References
54
Citations by year
2026: 9 · 2025: 4 · 2024: 9 · 2023: 15 · 2022: 16 · 2021: 16 · 2020: 25 · 2019: 26 · 2018: 18 · 2017: 13 · 2016: 15 · 2015: 22 · 2014: 18 · 2013: 17 · 2012: 25
FWCI
7.59
Type
journal article
Language
en
Open access
Locations
  • Journal of Biological Chemistry (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Archive ouverte UNIGE (University of Geneva) (submittedVersion, cc-by)
  • Archive ouverte UNIGE (University of Geneva) (submittedVersion)
Funders
  • National Institute on Aging (R01AG019519, AG19519)
  • National Institute of Allergy and Infectious Diseases (AI 20866, R01AI020866)
Topics
  • Life Sciences › Immunology and Microbiology › Immunology › Neutrophil, Myeloperoxidase and Oxidative Mechanisms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Redox biology and oxidative stress
  • Health Sciences › Medicine › Physiology › Nitric Oxide and Endothelin Effects
Keywords
NADPH oxidase 5, calcium activation, EF-hand, superoxide production, calcium binding sites, conformational change, intramolecular interactions
MeSH terms
NADPH Oxidase 5, Amino Acid Sequence, Binding Sites, Calcium, Cell Line, Cell-Free System, Enzyme Activation, Humans, Kinetics, Melitten, Membrane Proteins, Peptide Fragments, Protein Conformation, Superoxides, NADPH Oxidases

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