title: Crystal structure of human soluble adenylate cyclase reveals a distinct, highly flexible allosteric bicarbonate binding pocket.
abstract: Soluble adenylate cyclases catalyse the synthesis of the second messenger cAMP through the cyclisation of ATP and are the only known enzymes to be directly activated by bicarbonate. Here, we report the first crystal structure of the human enzyme that reveals a pseudosymmetrical arrangement of two catalytic domains to produce a single competent active site and a novel discrete bicarbonate binding pocket. Crystal structures of the apo protein, the protein in complex with α,β-methylene adenosine 5'-triphosphate (AMPCPP) and calcium, with the allosteric activator bicarbonate, and also with a number of inhibitors identified using fragment screening, all show a flexible active site that undergoes significant conformational changes on binding of ligands. The resulting nanomolar-potent inhibitors that were developed bind at both the substrate binding pocket and the allosteric site, and can be used as chemical probes to further elucidate the function of this protein.
authors.affiliation: Astex Pharmaceuticals, Cambridge Science Park, Cambridge, CB4 0QA (UK).
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Saalau-Bethell
authors.forename: Valerio
authors.initials: V
authors.lastname: Berdini
authors.forename: Anne
authors.initials: A
authors.lastname: Cleasby
authors.forename: Miles
authors.initials: M
authors.lastname: Congreve
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Coyle
authors.forename: Victoria
authors.initials: V
authors.lastname: Lock
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Murray
authors.forename: M Alistair
authors.initials: MA
authors.lastname: O'Brien
authors.forename: Sharna J
authors.initials: SJ
authors.lastname: Rich
authors.forename: Tracey
authors.initials: T
authors.lastname: Sambrook
authors.forename: Mladen
authors.initials: M
authors.lastname: Vinkovic
authors.forename: Jeff R
authors.initials: JR
authors.lastname: Yon
authors.forename: Harren
authors.initials: H
authors.lastname: Jhoti
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000737:chemistry / Q000378:metabolism; D001639:Bicarbonates / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D020134:Catalytic Domain / Q000187:drug effects; D018360:Crystallography, X-Ray; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008958:Models, Molecular; D013329:Structure-Activity Relationship
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D001639:Bicarbonates; D004791:Enzyme Inhibitors; C579271:ADCY10 protein, human; D000262:Adenylyl Cyclases
keywords: allosterism; drug discovery; enzyme regulation; fragment screening; structural biology