title: Activation of particulate guanylyl cyclase by Vibrio vulnificus hemolysin.
abstract: Recently we reported that Vibrio vulnificus hemolysin, an exotoxin produced by V. vulnificus, dilates rat thoracic aorta via elevated cGMP levels without affecting nitric oxide synthase. We investigated the mechanism further by observing the guanylyl cyclase activities in cytosolic, membrane, unfractionated, or reconstituted preparations. Hemolysin did not activate guanylyl cyclase in the membrane or cytosolic fraction, while it activated guanylyl cyclase in unfractionated or reconstituted preparation. The increased activity was not inhibited by the HS-142-1, a microbial polysaccharide which antagonizes atrial natriuretic peptide receptor, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor. However, it was attenuated by 6-(phenylamino)-5,8-quinolinedione (LY 83.583), which inhibits the catalytic domain of both guanylyl cyclases, and by cholesterol, which blocks hemolysin-incorporation into the membrane. Removing ATP, a cofactor of particulate guanylyl cyclase, attenuated the activation and ATPgammaS, a non-phosphorylating analog, restored it. These results suggest that V. vulnificus hemolysin activates particulate guanylyl cyclase via hemolysin incorporation into the vascular smooth muscle cell membrane in cooperation with certain unidentified cytosolic component(s).
authors.affiliation: Department of Pharmacology, Research Institute of Medical Sciences, Chonnam University Medical School, Kwangju, South Korea.
authors.forename: H
authors.initials: H
authors.lastname: Kook
authors.forename: J H
authors.initials: JH
authors.lastname: Rhee
authors.forename: S E
authors.initials: SE
authors.lastname: Lee
authors.forename: S Y
authors.initials: SY
authors.lastname: Kang
authors.forename: S S
authors.initials: SS
authors.lastname: Chung
authors.forename: K W
authors.initials: KW
authors.lastname: Cho
authors.forename: Y H
authors.initials: YH
authors.lastname: Baik
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000648:ultrastructure; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006162:Guanylate Cyclase / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D010069:Oxadiazoles / Q000494:pharmacology; D011134:Polysaccharides / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014733:Vibrio / Q000737:chemistry*