Intracellular Formation of "Undisruptable" Dimers of Inducible Nitric Oxide Synthase
Overproduction of nitric oxide (NO) by inducible NO synthase (iNOS) has been implicated in the pathogenesis of many diseases. iNOS is active only as a homodimer. Dimerization of iNOS represents a potentially critical target for therapeutic intervention. In this study, we show that intracellular iNOS...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 100; no. 24; pp. 14263 - 14268 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
25.11.2003
National Acad Sciences |
Subjects | |
Online Access | Get full text |
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Summary: | Overproduction of nitric oxide (NO) by inducible NO synthase (iNOS) has been implicated in the pathogenesis of many diseases. iNOS is active only as a homodimer. Dimerization of iNOS represents a potentially critical target for therapeutic intervention. In this study, we show that intracellular iNOS forms dimers that are "undisruptable" by boiling, denaturants, or reducing agents. Undisruptable (UD) dimers are clearly distinguishable from the easily dissociated dimers formed by iNOS in vitro. UD dimers do not form in Escherichia coli-expressed iNOS and could not be assembled in vitro, which suggests that an in vivo cellular process is required for their formation. iNOS UD dimers are not affected by intracellular depletion of H4B. However, the mutation of Cys-115 (critical for zinc binding) greatly affects the formation of UD dimers. This study reveals insight into the mechanisms of in vivo iNOS dimer formation. UD dimers represent a class of iNOS dimers that had not been suspected. This unanticipated finding revises our understanding of the mechanisms of iNOS dimerization and lays the groundwork for future studies aimed at modulating iNOS activity in vivo. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 This paper was submitted directly (Track II) to the PNAS office. To whom correspondence should be addressed at: Baylor College of Medicine, One Baylor Plaza, BCM 285 Room 672E, Houston, TX 77030. E-mail: teissa@bcm.tmc.edu. Edited by Louis J. Ignarro, University of California School of Medicine, Los Angeles, CA Abbreviations: iNOS, inducible NO synthase; l-NAME, Nω-nitro-l-Arg methyl ester; H4B, tetrahydrobiopterin; DAHP, 2,4-diamino-6-hydroxypyrimidine; UD, undisruptable. |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.2435290100 |