Ubiquitin recognition in endocytic trafficking – with or without ESCRT-0

Abstract

The ability to sense and adapt to the constantly changing environment is important for all organisms. Cell surface receptors and transporters are key for the fast response to extracellular stimuli and, thus, their abundance on the plasma membrane has to be strictly controlled. Heteromeric endosomal sorting complexes required for transport (ESCRTs) are responsible for mediating the post-translational degradation of endocytosed plasma membrane proteins in eukaryotes and are essential both in animals and plants. ESCRTs bind and sort ubiquitylated cargoes for vacuolar degradation. Although many components that comprise the multi-subunit ESCRT-0, ESCRT-I, ESCRT-II and ESCRT-III complexes are conserved in eukaryotes, plant and animal ESCRTs have diverged during the course of evolution. Homologues of ESCRT-0, which recognises ubiquitylated cargo, have emerged in metazoan and fungi but are not found in plants. Instead, the Arabidopsis genome encodes plant-specific ubiquitin adaptors and a greater number of target of Myb protein 1 (TOM1) homologues than in mammals. In this Review, we summarise and discuss recent findings on ubiquitin-binding proteins in Arabidopsis that could have equivalent functions to ESCRT-0. We further hypothesise that SH3 domain-containing proteins might serve as membrane curvature-sensing endophilin and amphiphysin homologues during plant endocytosis.

Global BioID-based SARS-CoV-2 proteins proximal interactome unveils novel ties between viral polypeptides and host factors involved in multiple COVID19-associated mechanisms

“…ADAM9 (Disintegrin and metalloproteinase domain-containing protein 9) cleaves multiple substrates involved in angiogenesis, may act as an alpha secretase for APP and has been involved in viral infection mechanisms 89 complex which directs endosomes towards lysosome and is crucial in multivesicular body formation. These proteins are dedicated to downregulating membrane receptors abundance 95 . Interestingly, the ESCRT-0 complex has also been involved in IL-2 and GM-CSF/L signal transduction 96 ).…”

TOLs Function as Ubiquitin Receptors in the Early Steps of the ESCRT Pathway in Higher Plants

“…Plants contain orthologs of most of the ESCRT proteins but lack canonical ESCRT-0 subunits (Winter and Hauser, 2006). Plantspecific substitutes for this subunit could be several ubiquitin receptors in the early endocytic pathway of plants (Mosesso et al, 2019). In Arabidopsis the conserved scaffolding protein, apoptosis-linked gene-2 interacting protein X (ALIX), binds membranes, ubiquitin, and K63-linked ubiquitin chains, and interacts with Vacuolar Sorting Protein 23A (VPS23A) and FYVE1 (Fab1, YOTB, Vac1, and EEA1)/FREE1 (FYVE DOMAIN PROTEIN REQUIRED FOR ENDOSOMAL SORTING 1), essential for ESCRT-I as well as ESCRT-III function (Cardona-Lopez et al, 2015;Kalinowska et al, 2015;Shen et al, 2018).…”

Protein Trafficking or Cell Signaling: A Dilemma for the Adaptor Protein TOM1

“…TOLs, components of the plant ESCRT machinery, function as a sorting tool for cargo degradation in the vacuole pathway (Moulinier-Anzola et al, 2020). TOLs interact with ubiquitinated cargo via their VHS and GAT domains, associate with phosphoinositides for membrane targeting at early endosomes, late endosomes, the Golgi apparatus, and the plasma membrane, and likely interface with ESCRT-I proteins (Korbei et al, 2013;Mosesso et al, 2019;Moulinier-Anzola et al, 2020). Multiple TOL isoforms with overlapping functions have been identified in plants, which may be required to quickly remove membrane cargo under environmental changes that require rapid adaptation.…”