TY - JOUR TI - Site-specific monoubiquitination downregulates Rab5 by disrupting effector binding and guanine nucleotide conversion AU - Shin, Donghyuk AU - Na, Wooju AU - Lee, Ji-Hyung AU - Kim, Gyuhee AU - Baek, Jiseok AU - Park, Seok Hee AU - Choi, Cheol Yong AU - Lee, Sangho A2 - Pfeffer, Suzanne R VL - 6 PY - 2017 DA - 2017/10/02 SP - e29154 C1 - eLife 2017;6:e29154 DO - 10.7554/eLife.29154 UR - https://doi.org/10.7554/eLife.29154 AB - Rab GTPases, which are involved in intracellular trafficking pathways, have recently been reported to be ubiquitinated. However, the functions of ubiquitinated Rab proteins remain unexplored. Here we show that Rab5 is monoubiquitinated on K116, K140, and K165. Upon co-transfection with ubiquitin, Rab5 exhibited abnormalities in endosomal localization and EGF-induced EGF receptor degradation. Rab5 K140R and K165R mutants restored these abnormalities, whereas K116R did not. We derived structural models of individual monoubiquitinated Rab5 proteins (mUbRab5s) by solution scattering and observed different conformational flexibilities in a site-specific manner. Structural analysis combined with biochemical data revealed that interactions with downstream effectors were impeded in mUbRab5K140, whereas GDP release and GTP loading activities were altered in mUbRab5K165. By contrast, mUbRab5K116 apparently had no effect. We propose a regulatory mechanism of Rab5 where monoubiquitination downregulates effector recruitment and GDP/GTP conversion in a site-specific manner. KW - Rab5 KW - ubiquitination KW - SAXS JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -