title: Structure of anthrax edema factor-calmodulin-adenosine 5'-(alpha,beta-methylene)-triphosphate complex reveals an alternative mode of ATP binding to the catalytic site.
abstract: Anthrax edema factor (EF) is a key virulence factor secreted by Bacillus anthracis. Here, we report a structure, at 3.0 A resolution, of the catalytic domain of EF (EF3) in complex with calmodulin (CaM) and adenosine 5'-(alpha,beta-methylene)-triphosphate (AMPCPP). Although the binding of the triphosphate of AMPCPP to EF3 can be superimposed on that of previously determined 3'deoxy-ATP (3'dATP) and 2'deoxy 3' anthraniloyl-ATP (2'd3' ANT-ATP) in EF3-CaM, the ribose and the adenine rings of AMPCPP are rotated approximately 105 and 180 degrees, respectively, relative to those of 3'dATP and 2'd3'ANT-ATP. Based on this model, K382 and F586 should play key roles in the recognition of adenine. However, mutations of these residues to alanine either separately or together cause only modest changes in Michaelis-Menten constants and IC50 values of AMPCPP and cAMP. Therefore, this alternate binding mode of the adenosine of AMPCPP binds to EF likely playing only a minor role in ATP binding and in catalysis.
authors.affiliation: Ben-May Institute for Cancer Research, The University of Chicago, 924 East 57th Street, Chicago, IL 60637, USA.
authors.forename: Yuequan
authors.initials: Y
authors.lastname: Shen
authors.forename: Qing
authors.initials: Q
authors.lastname: Guo
authors.forename: Natalia L
authors.initials: NL
authors.lastname: Zhukovskaya
authors.forename: Chester L
authors.initials: CL
authors.lastname: Drum
authors.forename: Andrew
authors.initials: A
authors.lastname: Bohm
authors.forename: Wei-Jen
authors.initials: WJ
authors.lastname: Tang
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000737:chemistry*; D000262:Adenylyl Cyclases / Q000737:chemistry*; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D001665:Binding Sites; D002147:Calmodulin / Q000737:chemistry*; D002384:Catalysis; D003067:Coenzymes / Q000737:chemistry; D003198:Computer Simulation; D004789:Enzyme Activation; D007700:Kinetics; D046911:Macromolecular Substances; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D002147:Calmodulin; D003067:Coenzymes; D046911:Macromolecular Substances; C030325:anthrax toxin; D000255:Adenosine Triphosphate; D000262:Adenylyl Cyclases; C002630:alpha,beta-methyleneadenosine 5'-triphosphate