title: Modeling the yew tree tubulin and a comparison of its interaction with paclitaxel to human tubulin.
abstract: OBJECTIVE
  To explore possible ways in which yew tree tubulin is naturally resistant to paclitaxel. While the yew produces a potent cytotoxin, paclitaxel, it is immune to paclitaxel's cytotoxic action.
  
  
  METHODS
  Tubulin sequence data for plant species were obtained from Alberta 1000 Plants Initiative. Sequences were assembled with Trinity de novo assembly program and tubulin identified. Homology modeling using MODELLER software was done to generate structures for yew tubulin. Molecular dynamics simulations and molecular mechanics Poisson-Boltzmann calculations were performed with the Amber package to determine binding affinity of paclitaxel to yew tubulin. ClustalW2 program and PHYLIP package were used to perform phylogenetic analysis on plant tubulin sequences.
  
  
  RESULTS
  We specifically analyzed several important regions in tubulin structure: the high-affinity paclitaxel binding site, as well as the intermediate binding site and microtubule nanopores. Our analysis indicates that the high-affinity binding site contains several substitutions compared to human tubulin, all of which reduce the binding energy of paclitaxel.
  
  
  CONCLUSIONS
  The yew has achieved a significant reduction of paclitaxel's affinity for its tubulin by utilizing several specific residue changes in the binding pocket for paclitaxel.
authors: Department of Oncology, University of Alberta, Edmonton, Alberta, Canada. jackt@ualberta.ca
authors: Jack A
authors: JA
authors: Tuszynski
authors: Travis J A
authors: TJ
authors: Craddock
authors: Jonathan Y
authors: JY
authors: Mane
authors: Khaled
authors: K
authors: Barakat
authors: Chih-Yuan
authors: CY
authors: Tseng
authors: Melissa
authors: M
authors: Gajewski
authors: Philip
authors: P
authors: Winter
authors: Laleh
authors: L
authors: Alisaraie
authors: Jordan
authors: J
authors: Patterson
authors: Eric
authors: E
authors: Carpenter
authors: Weiwei
authors: W
authors: Wang
authors: Michael K
authors: MK
authors: Deyholos
authors: Linji
authors: L
authors: Li
authors: Xiao
authors: X
authors: Sun
authors: Yong
authors: Y
authors: Zhang
authors: Gane Ka-Shu
authors: GK
authors: Wong
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D006801:Humans; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D017239:Paclitaxel / Q000737:chemistry* / Q000494:pharmacology; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D020946:Taxus / Q000737:chemistry* / Q000235:genetics; D013816:Thermodynamics; D014197:Trees / Q000737:chemistry* / Q000235:genetics; D014404:Tubulin / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism
chemical_list: D014404:Tubulin; D017239:Paclitaxel