Phosphorylation of threonine 497 in endothelial nitric-oxide synthase coordinates the coupling of L-arginine metabolism to efficient nitric oxide production
- There is evidence that endothelial nitric-oxide synthase (eNOS) is regulated by reciprocal dephosphorylation of Thr497 and phosphorylation of Ser1179. To examine the interrelationship between these sites, cells were transfected with wild-type (WT), T497A, T497D, S1179D, and T497A/S1179D eNOS and activity, NO release and eNOS localization were assessed. Although eNOS T497A, S1179D and T497A/S1179D eNOS had greater enzymatic activity than did WT eNOS in lysates, basal production of NO from cells was markedly reduced in cells transfected with T497A and T497A/S1179D eNOS but augmented in cells transfected with S1179D eNOS. Stimulating cells with ATP or ionophore normalized the loss of function seen with T497A and T497A/S1179D eNOS to levels observed with WT and S1179D eNOS, respectively. Despite these functional differences, the localization of eNOS mutants were similar to WT. Because both T497A and T497A/S1179D eNOS exhibited higher enzyme activity but reduced production of NO, we examined whether these mutations were “uncoupling” NO synthesis. T497A and T497A/S1179D eNOS generated 2-3 times more superoxide anion than WT eNOS, and both basal and stimulated interactions of T497A/S1179D eNOS with hsp90 were reduced in co-immunoprecipitation experiments. Thus, the phosphorylation/dephosphorylation of Thr497 may be an intrinsic switch mechanism that determines whether eNOS generates NO versus superoxide in cells.
Author: | Michelle I. Lin, David FultonORCiD, Roger Babbitt, Ingrid FlemingORCiDGND, Rudi BusseGND, Kirkwood A. PritchardORCiD, William C. SessaORCiD |
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URN: | urn:nbn:de:hebis:30:3-760915 |
DOI: | https://doi.org/10.1074/jbc.M302836200 |
ISSN: | 0021-9258 |
Pubmed Id: | https://pubmed.ncbi.nlm.nih.gov/12952971 |
Parent Title (English): | Journal of biological chemistry |
Publisher: | American Society for Biochemistry and Molecular Biology Publications |
Place of publication: | Bethesda, Md |
Document Type: | Article |
Language: | English |
Date of Publication (online): | 2021/01/04 |
Year of first Publication: | 2003 |
Publishing Institution: | Universitätsbibliothek Johann Christian Senckenberg |
Release Date: | 2024/02/04 |
Volume: | 278.2003 |
Issue: | 45 |
Page Number: | 8 |
First Page: | 44719 |
Last Page: | 44726 |
Institutes: | Medizin |
Dewey Decimal Classification: | 6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit |
Sammlungen: | Universitätspublikationen |
Licence (German): | Creative Commons - CC BY - Namensnennung 4.0 International |