title: Parkin stabilizes microtubules through strong binding mediated by three independent domains.
abstract: Mutations of parkin, a protein-ubiquitin isopeptide ligase (E3), appear to be the most frequent cause of familial Parkinson's disease (PD). Our previous studies have demonstrated that parkin binds strongly to alpha/beta tubulin heterodimers and microtubules. Here we show that the strong binding between parkin and tubulin, as well as that between parkin and microtubules, was mediated by three independent domains: linker, RING1, and RING2. These redundant strong interactions made it virtually impossible to separate parkin from microtubules by high concentrations of salt (3.8 m) or urea (0.5 m). Parkin co-purified with tubulin and was found in highly purified tubulin preparation. Expression of either full-length parkin or any of its three microtubule-binding domains significantly attenuated colchicine-induced microtubule depolymerization. The abilities of parkin to bind to and stabilize microtubules were not affected by PD-linked mutations that abrogate its E3 ligase activity. Thus, the tubulin/microtubule-binding activity of parkin and its E3 ligase activity are independent. The strong binding between parkin and tubulin/microtubules through three redundant interaction domains may not only stabilize microtubules but also guarantee the anchorage of this E3 ligase on microtubules. Because many misfolded proteins are transported on microtubules, the localization of parkin on microtubules may provide an important environment for its E3 ligase activity toward misfolded substrates.
authors.affiliation: Department of Physiology and Biophysics, State University of New York at Buffalo 14214, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.forename: Qian
authors.initials: Q
authors.lastname: Jiang
authors.forename: Jinghui
authors.initials: J
authors.lastname: Zhao
authors.forename: Yong
authors.initials: Y
authors.lastname: Ren
authors.forename: Mark D
authors.initials: MD
authors.lastname: Sutton
authors.forename: Jian
authors.initials: J
authors.lastname: Feng
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D015153:Blotting, Western; D002460:Cell Line; D002845:Chromatography; D003078:Colchicine / Q000494:pharmacology; D018076:DNA, Complementary / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D008954:Models, Biological; D009154:Mutation; D017239:Paclitaxel / Q000494:pharmacology; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012492:Salts / Q000494:pharmacology; D014162:Transfection; D014404:Tubulin / Q000737:chemistry; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism*; D014508:Urea / Q000494:pharmacology
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D018076:DNA, Complementary; D012492:Salts; D014404:Tubulin; D014508:Urea; D044767:Ubiquitin-Protein Ligases; C111567:parkin protein; D017239:Paclitaxel; D003078:Colchicine