Dissecting the Role of K61/K59 Residue in VPS4 Functions

ESCRTs (Endosomal Sorting Complexes Required for Transport) are required for the formation of the intraluminal vesicles in the multivesicular bodies and are involved in other topologically similar processes such as cytokinesis, nuclear envelope sealing and viral egress. The final complex ESCRT-III is disassembled by the recruitment and activation of the AAA-ATPase VPS4 to the endosomal membranes. This recruitment is due to the binding of VPS4 N-terminal MIT with MIM1 and MIM2 domains present in the CHMPs proteins. By analyzing different cellular membrane remodeling events in which VPS4 is involved, here we provide evidence that the K61 residue, mapping within the MIT domain of VPS4B (K59 in VPS4A), is involved in VPS4 functioning. Posttranslational modifications of this residue might modulate MIT-MIM2 binding affinity and, as a consequence, VPS4 functions.