title: Calmodulin-induced structural changes in endothelial nitric oxide synthase.
abstract: We have derived structures of intact calmodulin (CaM)-free and CaM-bound endothelial nitric oxide synthase (eNOS) by reconstruction from cryo-electron micrographs. The CaM-free reconstruction is well fitted by the oxygenase domain dimer, but the reductase domains are not visible, suggesting they are mobile and thus delocalized. Additional protein is visible in the CaM-bound reconstruction, concentrated in volumes near two basic patches on each oxygenase domain. One of these corresponds with a presumptive docking site for the reductase domain FMN-binding module. The other is proposed to correspond with a docking site for CaM. A model is suggested in which CaM binding and docking position the reductase domains near the oxygenase domains and promote docking of the FMN-binding modules required for electron transfer.
authors.affiliation: Division of Molecular Biology and Biochemistry and Division of Cell Biology and Biophysics, University of Missouri at Kansas City, 5007 Rockhill Rd, Kansas City, MO 64110-2499, USA. persechinia@umkc.edu
authors.forename: Anthony
authors.initials: A
authors.lastname: Persechini
authors.forename: Quang-Kim
authors.initials: QK
authors.lastname: Tran
authors.forename: D J
authors.initials: DJ
authors.lastname: Black
authors.forename: Edward P
authors.initials: EP
authors.lastname: Gogol
mesh_terms: D000818:Animals; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D002417:Cattle; D008958:Models, Molecular; D052250:Nitric Oxide Synthase Type III / Q000737:chemistry* / Q000378:metabolism*; D010105:Oxygenases / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D051381:Rats
chemical_list: D002147:Calmodulin; D010105:Oxygenases; D052250:Nitric Oxide Synthase Type III