title: Insights into the Distinct Mechanisms of Action of Taxane and Non-Taxane Microtubule Stabilizers from Cryo-EM Structures.
abstract: A number of microtubule (MT)-stabilizing agents (MSAs) have demonstrated or predicted potential as anticancer agents, but a detailed structural basis for their mechanism of action is still lacking. We have obtained high-resolution (3.9-4.2Å) cryo-electron microscopy (cryo-EM) reconstructions of MTs stabilized by the taxane-site binders Taxol and zampanolide, and by peloruside, which targets a distinct, non-taxoid pocket on β-tubulin. We find that each molecule has unique distinct structural effects on the MT lattice structure. Peloruside acts primarily at lateral contacts and has an effect on the "seam" of heterologous interactions, enforcing a conformation more similar to that of homologous (i.e., non-seam) contacts by which it regularizes the MT lattice. In contrast, binding of either Taxol or zampanolide induces MT heterogeneity. In doubly bound MTs, peloruside overrides the heterogeneity induced by Taxol binding. Our structural analysis illustrates distinct mechanisms of these drugs for stabilizing the MT lattice and is of relevance to the possible use of combinations of MSAs to regulate MT activity and improve therapeutic potential.
authors.affiliation: Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Kellogg
authors.affiliation: Graduate Group in Comparative Biochemistry, UC Berkeley, CA 94720, USA.
authors.forename: Nisreen M A
authors.initials: NMA
authors.lastname: Hejab
authors.affiliation: Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA.
authors.forename: Stuart
authors.initials: S
authors.lastname: Howes
authors.affiliation: Centre for Biodiscovery, Victoria University of Wellington, 6140, Wellington, New Zealand.
authors.forename: Peter
authors.initials: P
authors.lastname: Northcote
authors.affiliation: Centre for Biodiscovery, Victoria University of Wellington, 6140, Wellington, New Zealand.
authors.forename: John H
authors.initials: JH
authors.lastname: Miller
authors.affiliation: Chemical and Physical Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
authors.forename: J Fernando
authors.initials: JF
authors.lastname: Díaz
authors.affiliation: Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Downing
authors.affiliation: Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; QB3 Institute and Molecular and Cell Biology Department, University of California, Berkeley, CA 94720-3220, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA 94720-3220, USA. Electronic address: enogales@lbl.gov.
authors.forename: Eva
authors.initials: E
authors.lastname: Nogales
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry; D001665:Binding Sites; D001952:Bridged-Ring Compounds / Q000737:chemistry*; D020285:Cryoelectron Microscopy; D007091:Image Processing, Computer-Assisted; D018942:Macrolides / Q000737:chemistry; D008870:Microtubules / Q000737:chemistry*; D017239:Paclitaxel / Q000737:chemistry; D011506:Proteins / Q000737:chemistry; D043823:Taxoids / Q000737:chemistry*; D014404:Tubulin / Q000737:chemistry
chemical_list: D000970:Antineoplastic Agents; D001952:Bridged-Ring Compounds; D018942:Macrolides; D011506:Proteins; D043823:Taxoids; D014404:Tubulin; C444900:zampanolide; C080625:taxane; D017239:Paclitaxel
keywords: Taxol; cryo-EM; microtubule; microtubule-stabilizing agents; peloruside; zampanolide