tailieunhanh - Báo cáo khoa học: The E3 ubiquitin ligase Itch regulates sorting nexin 9 through an unconventional substrate recognition domain

The level of intracellular proteins is mainly regulated through modifications by ubiquitin ligases that target them for degradation. Members of the NEDD4 family of E3 ubiquitin ligases, such as Itch (atrophin-1 interacting protein 4), possess up to four WW domains for specific association with PY motif-containing substrates. | The E3 ubiquitin ligase Itch regulates sorting nexin 9 through an unconventional substrate recognition domain Claudia Baumann Cecilia K. Lindholm Donata Rimoldi and Frederic Levy1 Ludwig Institute for Cancer Research Ltd University of Lausanne Switzerland Keywords E3 ligase Itch protein-protein interaction sorting nexin 9 ubiquitin Correspondence C. Baumann Ludwig Institute for Cancer Research Ltd Chemin des Boveresses 155 CH-1066 Epalinges Switzerland Fax 41 21 692 59 95 Tel 41 21 692 59 77 E-mail Present address Philip Morris InternationalSA Neuchatel Switzerland Debiopharm SA Lausanne Switzerland Received 9 January 2010 revised 20 April 2010 accepted 27 April 2010 doi The level of intracellular proteins is mainly regulated through modifications by ubiquitin ligases that target them for degradation. Members of the NEDD4 family of E3 ubiquitin ligases such as Itch atrophin-1 interacting protein 4 possess up to four WW domains for specific association with PY motif-containing substrates. We have identified sorting nexin 9 SNX9 a protein involved in endocytic processes as a new substrate of Itch. Itch ubiquitylates SNX9 and regulates intracellular SNX9 levels. Using truncated proteins we found that the interaction with SNX9 is mediated by the proline-rich domain PRD of Itch a domain distinct from the conventional WW recognition domain and the SH3 domain of SNX9. Interaction with the PRD of Itch is essential for SNX9 ubiquitylation and degradation. Furthermore this effect is specific for Itch as NEDD4 a related PRD-containing E3 ligase does not bind SNX9. SNX18 a second member of the SNX family containing an SH3 domain was also found to bind to Itch. Our results indicate that the pool of substrates of NEDD4 family E3 ubiquitin ligases extends beyond proteins containing PY motifs. Structured digital abstract MINT-7889719 SNX18 uniprotkb Q96RF0 physically interacts MI 0915 with ITCH uni-protkb Q96J02 by anti