A unique mode of microtubule stabilization induced by peloruside A.
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.
Huzil
J Torin
JT
Division of Experimental Oncology, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, Canada.
Chik
John K
JK
Slysz
Gordon W
GW
Freedman
Holly
H
Tuszynski
Jack
J
Taylor
Richard E
RE
Sackett
Dan L
DL
Schriemer
David C
DC
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
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