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Substrate clustering potently regulates the activity of WW-HECT domain–containing ubiquitin ligases

The Nedd4 family of HECT domain–containing E3 ligases ubiquitinate many transcription factors and signaling proteins, and their activity is tightly regulated. Normally, intramolecular interactions curb the catalytic activity of the HECT domain, but these can be broken by the binding of PY motifs, fo...

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Detalles Bibliográficos
Autores principales: Mund, Thomas, Pelham, Hugh R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Biochemistry and Molecular Biology 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5892558/
https://www.ncbi.nlm.nih.gov/pubmed/29463679
http://dx.doi.org/10.1074/jbc.RA117.000934
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author Mund, Thomas
Pelham, Hugh R.
author_facet Mund, Thomas
Pelham, Hugh R.
author_sort Mund, Thomas
collection PubMed
description The Nedd4 family of HECT domain–containing E3 ligases ubiquitinate many transcription factors and signaling proteins, and their activity is tightly regulated. Normally, intramolecular interactions curb the catalytic activity of the HECT domain, but these can be broken by the binding of PY motifs, found on substrate molecules and adaptors, to the WW domains characteristic of this E3 ligase family. This raises the prospect of substrates automatically activating the ligases, frustrating the purpose of ligase regulation. Here we show that soluble protein substrates and adaptors such as α arrestins, even with multiple PY elements, cannot activate ligase activity efficiently. However, we found that polymerization or membrane tethering of these substrates dramatically increases the ligase activity both in vivo and in vitro. Aggregation of luciferase-containing substrates upon heat shock had a similar effect and could also expose cryptic PY elements in the substrates. We inferred that ligase activation critically requires a substantial array of clustered PY motifs and that the formation of such arrays on membranes or in polymeric aggregates may be an essential step in this mode of ligase regulation. We conclude that recruitment of α arrestins to membrane receptors and aggregation of unstable proteins after heat shock may be physiologically relevant mechanisms for triggering ubiquitination by Nedd4 family HECT domain–containing E3 ligases.
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spelling pubmed-58925582018-04-12 Substrate clustering potently regulates the activity of WW-HECT domain–containing ubiquitin ligases Mund, Thomas Pelham, Hugh R. J Biol Chem Cell Biology The Nedd4 family of HECT domain–containing E3 ligases ubiquitinate many transcription factors and signaling proteins, and their activity is tightly regulated. Normally, intramolecular interactions curb the catalytic activity of the HECT domain, but these can be broken by the binding of PY motifs, found on substrate molecules and adaptors, to the WW domains characteristic of this E3 ligase family. This raises the prospect of substrates automatically activating the ligases, frustrating the purpose of ligase regulation. Here we show that soluble protein substrates and adaptors such as α arrestins, even with multiple PY elements, cannot activate ligase activity efficiently. However, we found that polymerization or membrane tethering of these substrates dramatically increases the ligase activity both in vivo and in vitro. Aggregation of luciferase-containing substrates upon heat shock had a similar effect and could also expose cryptic PY elements in the substrates. We inferred that ligase activation critically requires a substantial array of clustered PY motifs and that the formation of such arrays on membranes or in polymeric aggregates may be an essential step in this mode of ligase regulation. We conclude that recruitment of α arrestins to membrane receptors and aggregation of unstable proteins after heat shock may be physiologically relevant mechanisms for triggering ubiquitination by Nedd4 family HECT domain–containing E3 ligases. American Society for Biochemistry and Molecular Biology 2018-04-06 2018-02-20 /pmc/articles/PMC5892558/ /pubmed/29463679 http://dx.doi.org/10.1074/jbc.RA117.000934 Text en © 2018 by The American Society for Biochemistry and Molecular Biology, Inc. Author's Choice—Final version free via Creative Commons CC-BY license (http://creativecommons.org/licenses/by/4.0) .
spellingShingle Cell Biology
Mund, Thomas
Pelham, Hugh R.
Substrate clustering potently regulates the activity of WW-HECT domain–containing ubiquitin ligases
title Substrate clustering potently regulates the activity of WW-HECT domain–containing ubiquitin ligases
title_full Substrate clustering potently regulates the activity of WW-HECT domain–containing ubiquitin ligases
title_fullStr Substrate clustering potently regulates the activity of WW-HECT domain–containing ubiquitin ligases
title_full_unstemmed Substrate clustering potently regulates the activity of WW-HECT domain–containing ubiquitin ligases
title_short Substrate clustering potently regulates the activity of WW-HECT domain–containing ubiquitin ligases
title_sort substrate clustering potently regulates the activity of ww-hect domain–containing ubiquitin ligases
topic Cell Biology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5892558/
https://www.ncbi.nlm.nih.gov/pubmed/29463679
http://dx.doi.org/10.1074/jbc.RA117.000934
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