Characterizing the Epothilone Binding Site on β-Tubulin by Photoaffinity Labeling: Identification of β-Tubulin Peptides TARGSQQY and TSRGSQQY as Targets of an Epothilone Photoprobe for Polymerized Tubulin

详细信息    查看全文

• 作者：Adwait R. Ranade ; LeeAnn Higgins ; Todd W. Markowski ; Nicole Glaser ; Dmitry Kashin ; Ruoli Bai ; Kwon Ho Hong ; Ernest Hamel ; Gerhard Höfle ; Gunda I. Georg
• 刊名：Journal of Medicinal Chemistry
• 出版年：2016
• 出版时间：April 14, 2016
• 年：2016
• 卷：59
• 期：7
• 页码：3499-3514
• 全文大小：946K
• 年卷期：0
• ISSN：1520-4804

文摘

Photoaffinity labeling with an epothilone A photoprobe led to the identification of the β-tubulin peptides TARGSQQY and TSRGSQQY as targets of the photoprobe for polymerized tubulin. These peptides represent residues 274–281 in different β-tubulin isotypes. Placing the carbene producing 21-diazo/triazolo moiety of the photoprobe in the vicinity of the TARGSQQY peptide in a homology model of TBB3 predicted a binding pose and conformation of the photoprobe that are very similar to the ones reported for 1) the high resolution cocrystal structure of epothilone A with an α,β-tubulin complex and for 2) a saturation transfer difference NMR and transferred NOESY NMR study of dimeric and polymerized tubulin. Our findings thus provide additional support for these models as physiologically the most relevant among several modes of binding that have been proposed for epothilone A in the taxane pocket of β-tubulin.