title: Structural Insights into the Inhibition of Tubulin by the Antitumor Agent 4β-(1,2,4-triazol-3-ylthio)-4-deoxypodophyllotoxin.
abstract: The colchicine domain is widely recognized as the binding site of microtubule depolymerization agents for anticancer drug design. Almost all of the drugs targeting the colchicine domain have been confirmed to bind to the tubulin β-subunit. Here we studied a crystal structure (2.3 Å) of the complex between tubulin and 4β-(1,2,4-triazol-3-ylthio)-4-deoxypodophyllotoxin (compound 1S) with superior antitumor activity, which was designed on the basis of the colchicine domain and synthesized in our previous work. A distinct binding model of the colchicine domain was found in the complexes of tubulin with compound 1S. From a comparison of the crystal structures of tubulin-compound 1S and tubulin-colchicine complexes, the side chains of the T7 loop of β-tubulin flip outward and the T5 loop of α-tubulin changes its conformation. It has been shown that the β-subunit T7 loop reversibly participates in resistance to straightening that opposes microtubule assembly by flipping in and out. Together with the biochemical results from compound 1S, the structural data highlight the main contributors in the α-subunits and the colchicine domain β-subunits: the dual-target binding sites in the α-T7 loop and β-H7-T7 loop of tubulin. Compound 1S can synchronously bind to αβ-tubulin. The structures also highlight common features for the design and development of novel potent microtubule destabilizing agents.
authors.affiliation: National Key Laboratory of Agromicrobiology, College of Food Sciences and Technology, Huazhong Agricultural University , Wuhan 430070, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei Key Laboratory of Industrial Microbiology, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology , Wuhan 430068, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhou
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, College of Life Sciences and Technology, Huazhong Agricultural University , Wuhan 430070, China.
authors.forename: Ze-Yuan
authors.initials: ZY
authors.lastname: Guan
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, College of Life Sciences and Technology, Huazhong Agricultural University , Wuhan 430070, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Yin
authors.affiliation: National Key Laboratory of Agromicrobiology, College of Food Sciences and Technology, Huazhong Agricultural University , Wuhan 430070, China.
authors.forename: Fusheng
authors.identifier: 0000-0002-5234-1590
authors.initials: F
authors.lastname: Chen
authors.affiliation: Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei Key Laboratory of Industrial Microbiology, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology , Wuhan 430068, China.
authors.forename: Ya-Jie
authors.identifier: 0000-0002-4032-2915
authors.initials: YJ
authors.lastname: Tang
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D004365:Drugs, Chinese Herbal; D008870:Microtubules / Q000378:metabolism; D011034:Podophyllotoxin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D058105:Polymerization; D011487:Protein Conformation; D013816:Thermodynamics; D014404:Tubulin / Q000187:drug effects*
chemical_list: D000970:Antineoplastic Agents; D004365:Drugs, Chinese Herbal; D014404:Tubulin; C014451:deoxypodophyllotoxin; D011034:Podophyllotoxin