title: Different Roles of N-Terminal and C-Terminal Domains in Calmodulin for Activation of Bacillus anthracis Edema Factor.
abstract: Bacillus anthracis adenylyl cyclase toxin edema factor (EF) is one component of the anthrax toxin and is essential for establishing anthrax disease. EF activation by the eukaryotic Ca2+-sensor calmodulin (CaM) leads to massive cAMP production resulting in edema. cAMP also inhibits the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase, thus reducing production of reactive oxygen species (ROS) used for host defense in activated neutrophils and thereby facilitating bacterial growth. Methionine (Met) residues in CaM, important for interactions between CaM and its binding partners, can be oxidized by ROS. We investigated the impact of site-specific oxidation of Met in CaM on EF activation using thirteen CaM-mutants (CaM-mut) with Met to leucine (Leu) substitutions. EF activation shows high resistance to oxidative modifications in CaM. An intact structure in the C-terminal region of oxidized CaM is sufficient for major EF activation despite altered secondary structure in the N-terminal region associated with Met oxidation. The secondary structures of CaM-mut were determined and described in previous studies from our group. Thus, excess cAMP production and the associated impairment of host defence may be afforded even under oxidative conditions in activated neutrophils.
authors.affiliation: Institute of Pharmacology, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover D-30625, Germany. luebker.carolin@mh-hannover.de.
authors.forename: Carolin
authors.initials: C
authors.lastname: Lübker
authors.affiliation: Institute of Pharmacy, University of Regensburg, Universitätsstr. 31, Regensburg D-93053, Germany. stefan.dove@chemie.uni-regensburg.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Dove
authors.affiliation: Ben May Department of Cancer Research, University of Chicago, 929 E. 57th Street, Chicago, IL 60637, USA. wtang@bsd.uchicago.edu.
authors.forename: Wei-Jen
authors.initials: WJ
authors.lastname: Tang
authors.affiliation: Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, GA 30602-2556, USA. ramonau@uga.edu.
authors.forename: Ramona J Bieber
authors.initials: RJ
authors.lastname: Urbauer
authors.affiliation: Department of Pharmacology and Toxicology, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA. moskovij@ku.edu.
authors.forename: Jackob
authors.initials: J
authors.lastname: Moskovitz
authors.affiliation: Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, GA 30602-2556, USA. urbauer@uga.edu.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Urbauer
authors.affiliation: Institute of Pharmacology, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover D-30625, Germany. seifert.roland@mh-hannover.de.
authors.forename: Roland
authors.initials: R
authors.lastname: Seifert
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics / Q000378:metabolism*; D019943:Amino Acid Substitution; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism*; D001408:Bacillus anthracis / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D002147:Calmodulin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D007930:Leucine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008715:Methionine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010084:Oxidation-Reduction; D017434:Protein Structure, Tertiary
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D002147:Calmodulin; C030325:anthrax toxin; D008715:Methionine; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; C106670:adenylyl cyclase 1; D007930:Leucine
keywords: (oxidized) calmodulin; (oxidized) calmodulin mutants; Bacillus anthracis edema factor; adenylyl cyclase toxin