Dataset Information

Alternative ubiquitin activation/conjugation cascades interact with N-end rule ubiquitin ligases to control degradation of RGS proteins.

ABSTRACT: Vertebrates express two enzymes for activation of ubiquitin-UBA1, which is responsible for activation of the vast majority of E2 conjugating enzymes, and UBA6, which uses the dedicated E2, USE1. However, targets and E3s for UBA6-USE1 are unknown. Here, we demonstrate that UBA6-USE1 functions with the UBR1-3 subfamily of N-recognin E3s to degrade the N-end rule substrates RGS4, RGS5, and Arg (R)-GFP. This pathway functions in the cytoplasm in parallel with the UBA1-UBE2A/B-UBR2 cascade, which promotes turnover of nuclear RGS4/5 proteins and an apparently phenotypically distinct pool of cytoplasmic RGS4/5. UBR2 promotes Lys48 (K48)-specific ubiquitin discharge from, and RGS4 ubiquitylation by, both USE1 and UBE2A in vitro. This work provides insight into the machinery employed by the UBA6-USE1 cascade to promote protein turnover and suggests that the UBA6 and UBA1 pathways can function in parallel with the same E3 to degrade the same targets in a spatially distinct manner.

SUBMITTER: Lee PC

PROVIDER: S-EPMC3151487 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature

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Alternative ubiquitin activation/conjugation cascades interact with N-end rule ubiquitin ligases to control degradation of RGS proteins.

Lee Peter C W PC Sowa Mathew E ME Gygi Steven P SP Harper J Wade JW

Molecular cell 20110801 3

Vertebrates express two enzymes for activation of ubiquitin-UBA1, which is responsible for activation of the vast majority of E2 conjugating enzymes, and UBA6, which uses the dedicated E2, USE1. However, targets and E3s for UBA6-USE1 are unknown. Here, we demonstrate that UBA6-USE1 functions with the UBR1-3 subfamily of N-recognin E3s to degrade the N-end rule substrates RGS4, RGS5, and Arg (R)-GFP. This pathway functions in the cytoplasm in parallel with the UBA1-UBE2A/B-UBR2 cascade, which pro ...[more]

PMID: 21816346

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Project description:The complement of fungal cell surface proteins is widely regulated by ubiquitination of membrane proteins, which results in their endocytosis and vacuolar degradation. For diverse fungal transporters, the specificity of ubiquitination is conferred by alpha arrestin adaptors, which recruit the Nedd4 family E3 ubiquitin ligase Rsp5. A recent study showed that one mammalian alpha arrestin also mediates ubiquitination and lysosomal trafficking of an activated plasma membrane receptor. Here we first screen all five widely-expressed human alpha arrestins for subcellular localization in ligand-stimulated and -unstimulated cells overexpressing the seven transmembrane receptor vasopressin 2. We then characterize the effects of alpha arrestins ARRDC3 and ARRDC4 upon activation of the seven transmembrane receptors vasopressin 2 and beta adrenergic 2. Using biochemical and imaging approaches, we show that ligand-activated receptors interact with alpha arrestins, and this results in recruitment of Nedd4 family E3 ubiquitin ligases and receptor ubiquitination - which are known to result in lysosomal trafficking. Our time course studies show these effects occur in the first 1-5 minutes after ligand activation, the same time that beta arrestins are known to have roles in receptor endocytic trafficking and kinase signaling. We tested the possibility that alpha and beta arrestins function coordinately and found co-immunoprecipitation and colocalization evidence to support this. Others recently reported that Arrdc3 knockout mice are lean and resistant to obesity. In the course of breeding our own Arrdc3-deficient mice, we observed two novel phenotypes in homozygotes: skin abnormalities, and embryonic lethality on normal chow diet, but not on high fat diet. Our findings suggest that alpha and beta arrestins function coordinately to maintain the optimal complement and function of cell surface proteins according to cellular physiological context and external signals. We discuss the implications of the alpha arrestin functions in fungi having evolved into coordinated alpha/beta arrestin functions in animals.

Dataset Information

Alternative ubiquitin activation/conjugation cascades interact with N-end rule ubiquitin ligases to control degradation of RGS proteins.

Publications

Alternative ubiquitin activation/conjugation cascades interact with N-end rule ubiquitin ligases to control degradation of RGS proteins.

Similar Datasets

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