title: Tailoring small molecules for an allosteric site on procaspase-6.
abstract: Although they represent attractive therapeutic targets, caspases have so far proven recalcitrant to the development of drugs targeting the active site. Allosteric modulation of caspase activity is an alternate strategy that potentially avoids the need for anionic and electrophilic functionality present in most active-site inhibitors. Caspase-6 has been implicated in neurodegenerative disease, including Huntington's and Alzheimer's diseases. Herein we describe a fragment-based lead discovery effort focused on caspase-6 in its active and zymogen forms. Fragments were identified for procaspase-6 using surface plasmon resonance methods and subsequently shown by X-ray crystallography to bind a putative allosteric site at the dimer interface. A fragment-merging strategy was employed to produce nanomolar-affinity ligands that contact residues in the L2 loop at the dimer interface, significantly stabilizing procaspase-6. Because rearrangement of the L2 loop is required for caspase-6 activation, our results suggest a strategy for the allosteric control of caspase activation with drug-like small molecules.
authors.affiliation: Departments of Structural Biology, Biochemical Pharmacology, Neuroscience, and Discovery Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080 (USA). murray.jeremy@gene.com.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Murray
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Giannetti
authors.forename: Micah
authors.initials: M
authors.lastname: Steffek
authors.forename: Paul
authors.initials: P
authors.lastname: Gibbons
authors.forename: Brian R
authors.initials: BR
authors.lastname: Hearn
authors.forename: Frederick
authors.initials: F
authors.lastname: Cohen
authors.forename: Christine
authors.initials: C
authors.lastname: Tam
authors.forename: Christine
authors.initials: C
authors.lastname: Pozniak
authors.forename: Brandon
authors.initials: B
authors.lastname: Bravo
authors.forename: Joe
authors.initials: J
authors.lastname: Lewcock
authors.forename: Priyadarshini
authors.initials: P
authors.lastname: Jaishankar
authors.forename: Cuong Q
authors.initials: CQ
authors.lastname: Ly
authors.forename: Xianrui
authors.initials: X
authors.lastname: Zhao
authors.forename: Yinyan
authors.initials: Y
authors.lastname: Tang
authors.forename: Preeti
authors.initials: P
authors.lastname: Chugha
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Arkin
authors.forename: John
authors.initials: J
authors.lastname: Flygare
authors.forename: Adam R
authors.initials: AR
authors.lastname: Renslo
mesh_terms: D000495:Allosteric Site; D001665:Binding Sites; D053178:Caspase 6 / Q000737:chemistry / Q000378:metabolism*; D018360:Crystallography, X-Ray; D019281:Dimerization; D015195:Drug Design; D004792:Enzyme Precursors / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D062105:Molecular Docking Simulation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D054852:Small Molecule Libraries / Q000737:chemistry* / Q000378:metabolism; D044366:Transition Temperature
chemical_list: D004792:Enzyme Precursors; D054852:Small Molecule Libraries; D053178:Caspase 6
keywords: caspase modulation; caspase-6; drug design; fragment merging; fragment screening