Trulsson, F. | Search bioRxiv

bioRxiv2020

Identification of proximal SUMO-dependent interactors using SUMO-ID

The fast dynamics and reversibility of posttranslational modifications by the ubiquitin family pose significant challenges for research. Here we present SUMO-ID, a technology that merges proximity biotinylation by TurboID and protein-fragment complementation to find SUMO-dependent interactors of proteins of interest. We developed an optimized split-TurboID version and show SUMO interaction-dependent labelling of proteins proximal to PML and RANGAP1. SUMO-dependent interactors of PML are involved in transcription, DNA damage, stress response and SUMO modification and are highly enriched in SUMO Interacting Motifs, but may only represent a subset of the total PML proximal proteome. Likewise, SUMO-ID also allowed us to identify novel interactors of SUMOylated SALL1, a less characterized SUMO substrate. Thus, SUMO-ID is a powerful tool that allows to study the consequences of SUMO-dependent interactions, and may further unravel the complexity of the ubiquitin code.

biochemistry↗

bioRxiv2020

ER-embedded UBE2J1/RNF26 ubiquitylation complex in spatio-temporal control of the endolysosomal pathway

The endolysosomal system fulfills a wide variety of cellular functions, many of which are modulated through interactions with other organelles. In particular, the ER exerts spatiotemporal constraints on the organization and motility of endosomes and lysosomes. We have recently described the ER transmembrane E3 ubiquitin ligase RNF26 to control perinuclear positioning and transport dynamics of the endolysosomal vesicular network. We now report that the ubiquitin conjugating enzyme UBE2J1, also anchored in the ER membrane, collaborates with RNF26 in this context, and that the cellular activity of this E2/E3 pair, localized in a perinuclear ER subdomain, is underpinned by transmembrane interactions. Through modification of its substrate SQSTM1/p62, the ER-embedded UBE2J1/RNF26 ubiquitylation complex recruits endosomal adaptors to immobilize their cognate vesicles in the perinuclear region. The resulting spatiotemporal compartmentalization of the endolysosomal system between the perinuclear vesicle cloud and the cell periphery facilitates timely downregulation of endocytosed cargoes, such as EGFR.

cell biology↗