Proteomic analysis reveals novel ligands and substrates for LNX1 E3 ubiquitin ligase

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dc.contributor.authorLenihan, Joan A.
dc.contributor.authorSaha, Orthis
dc.contributor.authorYoung, Paul W.
dc.contributor.funderIrish Research Council
dc.contributor.funderScience Foundation Ireland
dc.date.accessioned2018-02-06T13:36:27Z
dc.date.available2018-02-06T13:36:27Z
dc.date.issued2017
dc.description.abstractLigand of Numb protein X1 (LNX1) is an E3 ubiquitin ligase that contains a catalytic RING (Really Interesting New Gene) domain and four PDZ (PSD-95, DlgA, ZO-1) domains. LNX1 can ubiquitinate Numb, as well as a number of other ligands. However, the physiological relevance of these interactions in vivo remain unclear. To gain functional insights into the LNX family, we have characterised the LNX1 interactome using affinity purification and mass spectrometry. This approach identified a large number of novel LNX1-interacting proteins, as well as confirming known interactions with NUMB and ERC2. Many of the novel interactions mapped to the LNX PDZ domains, particularly PDZ2, and many showed specificity for LNX1 over the closely related LNX2. We show that PPFIA1 (liprin-α1), KLHL11, KIF7 and ERC2 are substrates for ubiquitination by LNX1. LNX1 ubiquitination of liprin-α1 is dependent on a PDZ binding motif containing a carboxyl terminal cysteine that binds LNX1 PDZ2. Surprisingly, the neuronally-expressed LNX1p70 isoform, that lacks the RING domain, was found to promote ubiquitination of PPFIA1 and KLHL11, albeit to a lesser extent than the longer RING-containing LNX1p80 isoform. Of several E3-ligases identified in the LNX1 interactome we confirm interactions of LNX1 with MID2/TRIM1 and TRIM27. On this basis we propose a model whereby LNX1p70, despite lacking a catalytic RING domain, may function as a scaffold to promote ubiquitination of its ligands through recruitment of other E3-ligases. These findings provide functional insights into the LNX protein family, particularly the neuronal LNX1p70 isoform.en
dc.description.sponsorshipIrish Research Council (EMBARK)en
dc.description.statusPeer revieweden
dc.description.versionPublished Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.articleide0187352
dc.identifier.citationLenihan, J. A., Saha, O. and Young, P. W. (2017) 'Proteomic analysis reveals novel ligands and substrates for LNX1 E3 ubiquitin ligase', PLOS ONE, 12(11), e0187352 (18pp). doi: 10.1371/journal.pone.0187352en
dc.identifier.doi10.1371/journal.pone.0187352
dc.identifier.endpage18
dc.identifier.issued11
dc.identifier.journaltitlePLoS ONEen
dc.identifier.startpage1
dc.identifier.urihttps://hdl.handle.net/10468/5379
dc.identifier.volume12
dc.language.isoenen
dc.publisherPublic Library of Scienceen
dc.relation.projectinfo:eu-repo/grantAgreement/SFI/SFI Research Frontiers Programme (RFP)/08/RFP/NSC1382/IE/Investigation of the function of the LNX family of E3 ubiquitin ligases in the nervous system/
dc.relation.urihttp://journals.plos.org/plosone/article?id=10.1371/journal.pone.0187352
dc.rights© 2017, Lenihan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectPhosphotyrosine-binding domainen
dc.subjectMammalian numben
dc.subjectProteinen
dc.subjectFamilyen
dc.subjectDifferentiationen
dc.subjectIdentificationen
dc.subjectUbiquitylationen
dc.subjectSpecificityen
dc.subjectCellsen
dc.subjectTighten
dc.titleProteomic analysis reveals novel ligands and substrates for LNX1 E3 ubiquitin ligaseen
dc.typeArticle (peer-reviewed)en
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