title: A unique mode of microtubule stabilization induced by peloruside A.
abstract: Microtubules are significant therapeutic targets for the treatment of cancer, where suppression of microtubule dynamicity by drugs such as paclitaxel forms the basis of clinical efficacy. Peloruside A, a macrolide isolated from New Zealand marine sponge Mycale hentscheli, is a microtubule-stabilizing agent that synergizes with taxoid drugs through a unique site and is an attractive lead compound in the development of combination therapies. We report here unique allosteric properties of microtubule stabilization via peloruside A and present a structural model of the peloruside-binding site. Using a strategy involving comparative hydrogen-deuterium exchange mass spectrometry of different microtubule-stabilizing agents, we suggest that taxoid-site ligands epothilone A and docetaxel stabilize microtubules primarily through improved longitudinal interactions centered on the interdimer interface, with no observable contributions from lateral interactions between protofilaments. The mode by which peloruside A achieves microtubule stabilization also involves the interdimer interface, but includes contributions from the alpha/beta-tubulin intradimer interface and protofilament contacts, both in the form of destabilizations. Using data-directed molecular docking simulations, we propose that peloruside A binds within a pocket on the exterior of beta-tubulin at a previously unknown ligand site, rather than on alpha-tubulin as suggested in earlier studies.
authors.affiliation: Division of Experimental Oncology, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, Canada.
authors.forename: J Torin
authors.initials: JT
authors.lastname: Huzil
authors.forename: John K
authors.initials: JK
authors.lastname: Chik
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Slysz
authors.forename: Holly
authors.initials: H
authors.lastname: Freedman
authors.forename: Jack
authors.initials: J
authors.lastname: Tuszynski
authors.forename: Richard E
authors.initials: RE
authors.lastname: Taylor
authors.forename: Dan L
authors.initials: DL
authors.lastname: Sackett
authors.forename: David C
authors.initials: DC
authors.lastname: Schriemer
mesh_terms: D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D019281:Dimerization; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000737:chemistry; D007783:Lactones / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D013058:Mass Spectrometry; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment; D014404:Tubulin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D050257:Tubulin Modulators / Q000737:chemistry / Q000378:metabolism
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D019086:Bridged Bicyclo Compounds, Heterocyclic; D007783:Lactones; D008024:Ligands; D010455:Peptides; D020033:Protein Isoforms; D014404:Tubulin; D050257:Tubulin Modulators; C414085:peloruside A; C004805:5'-guanylylmethylenebisphosphonate; D006160:Guanosine Triphosphate