Bro1 binds the Vps20 subunit ofESCRT‐IIIand promotesESCRT‐IIIregulation by Doa4

Abstract

The budding of intralumenal vesicles (ILVs) at endosomes requires membrane scission by the ESCRT‐III complex. This step is negatively regulated in yeast by Doa4, the ubiquitin hydrolase that deubiquitinates transmembrane proteins sorted as cargoes into ILVs. Doa4 acts non‐enzymatically to inhibit ESCRT‐III membrane scission activity by directly binding the Snf7 subunit of ESCRT‐III. This interaction inhibits the remodeling/disassembly of Snf7 polymers required for the ILV membrane scission reaction. Thus, Doa4 is thought to have a structural role that delays ILV budding while it also functions enzymatically to deubiquitinate ILV cargoes. In this study, we show that Doa4 binding to Snf7 in vivo is antagonized by another ESCRT‐III subunit, Vps20. Doa4 is restricted from interacting with Snf7 in yeast expressing a mutant Vps20 allele that constitutively binds Doa4. This inhibitory effect of Vps20 is suppressed by overexpression of another ESCRT‐III‐associated protein, Bro1. We show that Bro1 binds directly to Vps20, suggesting that Bro1 has a central role in relieving the antagonistic relationship that Vps20 has toward Doa4.

The Bro1-like domain-containing protein, AtBro1, modulates growth and abiotic stress responses in Arabidopsis

“…For example, in yeast (Odorizzi et al, 2003), the viability of bro1 cells is reduced during nutrient starvation, resulting in defective regulation of cell proliferation (Nickas and Yaffe, 1996). Doa4, a ubiquitin thiolesterase that regulates membrane scission in endosomes, requires Bro1 for its recruitment to endosomal membranes (Luhtala and Odorizzi, 2004;Buysse et al, 2022). In anaerobic parasitic amoebozoans, multivascular body (MVB) formation during phagocytosis has been reported to be mediated by EhADH112, a Bro1 domain protein, on the cell surface and in endosomal compartments (Bañuelos et al, 2012;Pashkova et al, 2013).…”