title: Interaction with adenylate cyclase toxin fromBordetella pertussisaffects the metal binding properties of calmodulin.
abstract: Adenylate cyclase toxin domain (CyaA-ACD) is a calmodulin (CaM)-dependent adenylate cyclase involved inBordetella pertussispathogenesis. Calcium (Ca2+) and magnesium (Mg2+) concentrations impact CaM-dependent CyaA-ACD activation, but the structural mechanisms remain unclear. In this study, NMR, dynamic light scattering, and native PAGE were used to probe Mg2+-induced transitions in CaM's conformation in the presence of CyaA-ACD. Mg2+binding was localized to sites I and II, while sites III and IV remained Ca2+loaded when CaM was bound to CyaA-ACD. 2Mg2+/2Ca2+-loaded CaM/CyaA-ACD was elongated, whereas mutation of site I altered global complex conformation. These data suggest that CyaA-ACD interaction moderates CaM's Ca2+- and Mg2+-binding capabilities, which may contribute to pathobiology.
authors.affiliation: Department of Microbiology Miami University Oxford OH USA.
authors.forename: Tzvia I
authors.initials: TI
authors.lastname: Springer
authors.affiliation: Department of Microbiology Miami University Oxford OH USA; Present address: Department of Pharmacology Cleveland Center for Membrane and Structural Biology Case Western Reserve University Cleveland OH 44106 USA.
authors.forename: Corey C
authors.initials: CC
authors.lastname: Emerson
authors.affiliation: Cell, Molecular, and Structural Biology Program Miami University Oxford OH USA.
authors.forename: Christian W
authors.initials: CW
authors.lastname: Johns
authors.affiliation: Department of Microbiology Miami University Oxford OH USA; Cell, Molecular, and Structural Biology Program Miami University Oxford OH USA.
authors.forename: Natosha L
authors.identifier: 0000-0002-8891-5023
authors.initials: NL
authors.lastname: Finley
keywords: adenylate cyclase; calcium; calmodulin; magnesium; nuclear magnetic resonance