Phosphorylation-Dependent Activation of the ESCRT Function of ALIX in Cytokinetic Abscission and Retroviral Budding.

Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77230, USA; Experimental Therapeutics Academic Program, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA. AbMax Biotechnology, Beijing 100085, China. Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77230, USA. Experimental Therapeutics Academic Program, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA; Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77230, USA; Experimental Therapeutics Academic Program, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA. Electronic address: jkuang@mdanderson.org.

Developmental cell. 2016;(3):331-43
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Abstract

The modular adaptor protein ALIX is a key player in multiple ESCRT-III-mediated membrane remodeling processes. ALIX is normally present in a closed conformation due to an intramolecular interaction that renders ALIX unable to perform its ESCRT functions. Here we demonstrate that M phase-specific phosphorylation of the intramolecular interaction site within the proline-rich domain (PRD) of ALIX transforms cytosolic ALIX from closed to open conformation. Defining the role of this mechanism of ALIX regulation in three classical ESCRT-mediated processes revealed that phosphorylation of the intramolecular interaction site in the PRD is required for ALIX to function in cytokinetic abscission and retroviral budding, but not in multivesicular body sorting of activated epidermal growth factor receptor. Thus, phosphorylation of the intramolecular interaction site in the PRD is one of the major mechanisms that activates the ESCRT function of ALIX.