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Abstract
The post-translational modification of proteins with ubiquitin plays a central role in nearly all aspects of eukaryotic biology. Historically, studies have focused on the conjugation of ubiquitin to lysine residues in substrates, but it is now clear that ubiquitylation can also occur on cysteine, serine, and threonine residues, as well as on the N-terminal amino group of proteins. Paradigm-shifting reports of non-proteinaceous substrates have further extended the reach of ubiquitylation beyond the proteome to include intracellular lipids and sugars. Additionally, results from bacteria have revealed novel ways to ubiquitylate (and deubiquitylate) substrates without the need for any of the enzymatic components of the canonical ubiquitylation cascade. Focusing mainly upon recent findings, this review aims to outline the current understanding of non-lysine ubiquitylation and speculate upon the molecular mechanisms and physiological importance of this non-canonical modification.
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Kelsall IR, McCrory EH, Xu Y, Scudamore CL, Nanda SK, Mancebo-Gamella P, Wood NT, Knebel A, Matthews SJ, Cohen P. HOIL-1 ubiquitin ligase activity targets unbranched glucosaccharides and is required to prevent polyglucosan accumulation. EMBO J 2022; 41:e109700. [PMID: 35274759 PMCID: PMC9016349 DOI: 10.15252/embj.2021109700] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 01/05/2022] [Accepted: 02/16/2022] [Indexed: 01/12/2023] Open
Abstract
HOIL-1, a component of the linear ubiquitin chain assembly complex (LUBAC), ubiquitylates serine and threonine residues in proteins by esterification. Here, we report that mice expressing an E3 ligase-inactive HOIL-1[C458S] mutant accumulate polyglucosan in brain, heart and other organs, indicating that HOIL-1's E3 ligase activity is essential to prevent these toxic polysaccharide deposits from accumulating. We found that HOIL-1 monoubiquitylates glycogen and α1:4-linked maltoheptaose in vitro and identify the C6 hydroxyl moiety of glucose as the site of ester-linked ubiquitylation. The monoubiquitylation of maltoheptaose was accelerated > 100-fold by the interaction of Met1-linked or Lys63-linked ubiquitin oligomers with the RBR domain of HOIL-1. HOIL-1 also transferred pre-formed ubiquitin oligomers to maltoheptaose en bloc, producing polyubiquitylated maltoheptaose in one catalytic step. The Sharpin and HOIP components of LUBAC, but not HOIL-1, bound to unbranched and infrequently branched glucose polymers in vitro, but not to highly branched mammalian glycogen, suggesting a potential function in targeting HOIL-1 to unbranched glucosaccharides in cells. We suggest that monoubiquitylation of unbranched glucosaccharides may initiate their removal from cells, preventing precipitation as polyglucosan.
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Affiliation(s)
- Ian R Kelsall
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Elisha H McCrory
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Yingqi Xu
- Cross-Faculty NMR Centre, Department of Life Sciences, Imperial College London, London, UK
| | | | - Sambit K Nanda
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Paula Mancebo-Gamella
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Nicola T Wood
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Axel Knebel
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Stephen J Matthews
- Cross-Faculty NMR Centre, Department of Life Sciences, Imperial College London, London, UK
| | - Philip Cohen
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
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Cohen P, Kelsall IR, Nanda SK, Zhang J. HOIL-1, an atypical E3 ligase that controls MyD88 signalling by forming ester bonds between ubiquitin and components of the Myddosome. Adv Biol Regul 2020; 75:100666. [PMID: 31615747 PMCID: PMC7132539 DOI: 10.1016/j.jbior.2019.100666] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 09/19/2019] [Accepted: 09/30/2019] [Indexed: 12/18/2022]
Abstract
Components of bacteria and viruses activate Toll-Like Receptors in host cells, triggering the formation of the Myddosome and a signalling network that culminates in the production and release of the inflammatory mediators required to combat pathogenic infection. The Myddosome initiates signalling by recruiting and activating five E3 ligases that generate hybrid ubiquitin chains and attach them to components of the Myddosome. These ubiquitin chains act as a scaffold for the recruitment and activation of ubiquitin-binding proteins, which include the "master" protein kinases TAK1 and IKKβ that drive inflammatory mediator production, as well as other proteins like ABIN1 and A20 that restrict activation of the network to prevent the overproduction of these substances that can lead to autoimmunity and organ damage. Here we review recent developments in our understanding of this network, focusing on the unexpected discovery that the E3 ligase HOIL-1 initiates the formation of hybrid ubiquitin chains by forming an ester bond between the first ubiquitin and the protein components of the Myddosome.
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Affiliation(s)
- Philip Cohen
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Scotland, United Kingdom.
| | - Ian R Kelsall
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Scotland, United Kingdom
| | - Sambit K Nanda
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Scotland, United Kingdom
| | - Jiazhen Zhang
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Scotland, United Kingdom
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Kelsall IR, Kristariyanto YA, Knebel A, Wood NT, Kulathu Y, Alpi AF. Coupled monoubiquitylation of the co-E3 ligase DCNL1 by Ariadne-RBR E3 ubiquitin ligases promotes cullin-RING ligase complex remodeling. J Biol Chem 2018; 294:2651-2664. [PMID: 30587576 PMCID: PMC6393609 DOI: 10.1074/jbc.ra118.005861] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/07/2018] [Indexed: 12/29/2022] Open
Abstract
Cullin-RING E3 ubiquitin ligases (CRLs) are large and diverse multisubunit protein complexes that contribute to about one-fifth of ubiquitin-dependent protein turnover in cells. CRLs are activated by the attachment of the ubiquitin-like protein neural precursor cell expressed, developmentally down-regulated 8 (NEDD8) to the cullin subunits. This cullin neddylation is essential for a plethora of CRL-regulated cellular processes and is vital for life. In mammals, neddylation is promoted by the five co-E3 ligases, defective in cullin neddylation 1 domain-containing 1–5 (DCNL1–5); however, their functional regulation within the CRL complex remains elusive. We found here that the ubiquitin-associated (UBA) domain–containing DCNL1 is monoubiquitylated when bound to CRLs and that this monoubiquitylation depends on the CRL-associated Ariadne RBR ligases TRIAD1 (ARIH2) and HHARI (ARIH1) and strictly requires the DCNL1's UBA domain. Reconstitution of DCNL1 monoubiquitylation in vitro revealed that autoubiquitylated TRIAD1 mediates binding to the UBA domain and subsequently promotes a single ubiquitin attachment to DCNL1 in a mechanism previously dubbed coupled monoubiquitylation. Moreover, we provide evidence that DCNL1 monoubiquitylation is required for efficient CRL activity, most likely by remodeling CRLs and their substrate receptors. Collectively, this work identifies DCNL1 as a critical target of Ariadne RBR ligases and coupled monoubiquitylation of DCNL1 as an integrated mechanism that affects CRL activity and client–substrate ubiquitylation at multiple levels.
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Affiliation(s)
- Ian R Kelsall
- From the MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Yosua A Kristariyanto
- From the MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Axel Knebel
- From the MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Nicola T Wood
- From the MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Yogesh Kulathu
- From the MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Arno F Alpi
- From the MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
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Scott DC, Hammill JT, Min J, Rhee DY, Connelly M, Sviderskiy VO, Bhasin D, Chen Y, Ong SS, Chai SC, Goktug AN, Huang G, Monda JK, Low J, Kim HS, Paulo JA, Cannon JR, Shelat AA, Chen T, Kelsall IR, Alpi AF, Pagala V, Wang X, Peng J, Singh B, Harper JW, Schulman BA, Guy RK. Blocking an N-terminal acetylation-dependent protein interaction inhibits an E3 ligase. Nat Chem Biol 2017; 13:850-857. [PMID: 28581483 PMCID: PMC5577376 DOI: 10.1038/nchembio.2386] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 04/07/2017] [Indexed: 12/25/2022]
Abstract
N-terminal acetylation is an abundant modification influencing protein functions. Since ≈80% of mammalian cytosolic proteins are N-terminally acetylated, this potentially represents an untapped target for chemical control of their functions. Structural studies have revealed that, like lysine acetylation, N-terminal acetylation converts a positively charged amine into a hydrophobic handle that mediates protein interactions, suggesting it may be a druggable target. We report the development of chemical probes targeting the N-terminal acetylation-dependent interaction between an E2 conjugating enzyme (UBE2M, aka UBC12) and DCN1 (aka DCUN1D1), a subunit of a multiprotein E3 ligase for the ubiquitin-like protein NEDD8. The inhibitors are highly selective with respect to other protein acetyl amide binding sites, inhibit NEDD8 ligation in vitro and in cells, and suppress the anchorage-independent growth of a cell line harboring DCN1 amplification. Overall, the data demonstrate that N-terminal acetyl-dependent protein interactions are druggable targets, and provide insights into targeting multiprotein E2–E3 ligases.
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Affiliation(s)
- Daniel C Scott
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.,Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Jared T Hammill
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Jaeki Min
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - David Y Rhee
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Michele Connelly
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Vladislav O Sviderskiy
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Deepak Bhasin
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Yizhe Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Su-Sien Ong
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Sergio C Chai
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Asli N Goktug
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Guochang Huang
- Laboratory of Epithelial Cancer Biology, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| | - Julie K Monda
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Jonathan Low
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Ho Shin Kim
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Joe R Cannon
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Anang A Shelat
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Ian R Kelsall
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Arno F Alpi
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Vishwajeeth Pagala
- St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Xusheng Wang
- St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Junmin Peng
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.,St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Bhuvanesh Singh
- Laboratory of Epithelial Cancer Biology, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| | - J Wade Harper
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Brenda A Schulman
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.,Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - R Kip Guy
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
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Kelsall IR, Duda DM, Olszewski JL, Hofmann K, Knebel A, Langevin F, Wood N, Wightman M, Schulman BA, Alpi AF. TRIAD1 and HHARI bind to and are activated by distinct neddylated Cullin-RING ligase complexes. EMBO J 2013; 32:2848-60. [PMID: 24076655 PMCID: PMC3817463 DOI: 10.1038/emboj.2013.209] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 09/04/2013] [Indexed: 11/26/2022] Open
Abstract
RING (Really Interesting New Gene)-in-between-RING (RBR) enzymes are a distinct class of E3 ubiquitin ligases possessing a cluster of three zinc-binding domains that cooperate to catalyse ubiquitin transfer. The regulation and biological function for most members of the RBR ligases is not known, and all RBR E3s characterized to date are auto-inhibited for in vitro ubiquitylation. Here, we show that TRIAD1 and HHARI, two members of the Ariadne subfamily ligases, associate with distinct neddylated Cullin-RING ligase (CRL) complexes. In comparison to the modest E3 ligase activity displayed by isolated TRIAD1 or HHARI, binding of the cognate neddylated CRL to TRIAD1 or HHARI greatly stimulates RBR ligase activity in vitro, as determined by auto-ubiquitylation, their ability to stimulate dissociation of a thioester-linked UBCH7∼ubiquitin intermediate, and reactivity with ubiquitin-vinyl methyl ester. Moreover, genetic evidence shows that RBR ligase activity impacts both the levels and activities of neddylated CRLs in vivo. Cumulatively, our work proposes a conserved mechanism of CRL-induced Ariadne RBR ligase activation and further suggests a reciprocal role of this special class of RBRs as regulators of distinct CRLs. Ubiquitin ligases of the distinct Cullin-RING ligase (CRL) and RING-between-RING (RBR) families physically and functionally interact, suggesting how RBR ligase auto-inhibition may be relieved in Ariadne-subfamily members.
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Affiliation(s)
- Ian R Kelsall
- 1] Scottish Institute for Cell Signalling, College of Life Sciences, University of Dundee, Dundee, UK [2] Medical Research Council Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee, UK
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Kelsall IR, Langenick J, MacKay C, Patel KJ, Alpi AF. The Fanconi anaemia components UBE2T and FANCM are functionally linked to nucleotide excision repair. PLoS One 2012; 7:e36970. [PMID: 22615860 PMCID: PMC3352854 DOI: 10.1371/journal.pone.0036970] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2012] [Accepted: 04/10/2012] [Indexed: 11/24/2022] Open
Abstract
The many proteins that function in the Fanconi anaemia (FA) monoubiquitylation pathway initiate replicative DNA crosslink repair. However, it is not clear whether individual FA genes participate in DNA repair pathways other than homologous recombination and translesion bypass. Here we show that avian DT40 cell knockouts of two integral FA genes – UBE2T and FANCM are unexpectedly sensitive to UV-induced DNA damage. Comprehensive genetic dissection experiments indicate that both of these FA genes collaborate to promote nucleotide excision repair rather than translesion bypass to protect cells form UV genotoxicity. Furthermore, UBE2T deficiency impacts on the efficient removal of the UV-induced photolesion cyclobutane pyrimidine dimer. Therefore, this work reveals that the FA pathway shares two components with nucleotide excision repair, intimating not only crosstalk between the two major repair pathways, but also potentially identifying a UBE2T-mediated ubiquitin-signalling response pathway that contributes to nucleotide excision repair.
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Affiliation(s)
- Ian R. Kelsall
- Scottish Institute for Cell Signalling, University of Dundee, Dundee, United Kingdom
| | | | - Craig MacKay
- Scottish Institute for Cell Signalling, University of Dundee, Dundee, United Kingdom
| | - Ketan J. Patel
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Arno F. Alpi
- Scottish Institute for Cell Signalling, University of Dundee, Dundee, United Kingdom
- * E-mail:
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Kelsall IR, Voss M, Munro S, Cuthbertson DJR, Cohen PTW. R3F, a novel membrane-associated glycogen targeting subunit of protein phosphatase 1 regulates glycogen synthase in astrocytoma cells in response to glucose and extracellular signals. J Neurochem 2011; 118:596-610. [DOI: 10.1111/j.1471-4159.2011.07345.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Voss M, Paterson J, Kelsall IR, Martín-Granados C, Hastie CJ, Peggie MW, Cohen PTW. Ppm1E is an in cellulo AMP-activated protein kinase phosphatase. Cell Signal 2010; 23:114-24. [PMID: 20801214 DOI: 10.1016/j.cellsig.2010.08.010] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 08/17/2010] [Indexed: 11/27/2022]
Abstract
Activation of 5'-AMP-activated protein kinase (AMPK) is believed to be the mechanism by which the pharmaceuticals, metformin and phenformin, exert their beneficial effects for treatment of type 2 diabetes. These biguanide drugs elevate 5'-AMP, which allosterically activates AMPK and promotes phosphorylation on Thr172 of AMPK catalytic α subunits. Although kinases phosphorylating this site have been identified, phosphatases that dephosphorylate it are unknown. The aim of this study is to identify protein phosphatase(s) that dephosphorylate AMPKα-Thr172 within cells. Our initial data indicated that members of the protein phosphatase Mg/Mn(2+)-dependent [corrected] (PPM) family and not those of the PPP family of protein serine/threonine phosphatases may be directly or indirectly inhibited by phenformin. Using antibodies raised to individual Ppm phosphatases that facilitated the assessment of their activities, phenformin stimulation of cells was found to decrease the Mg(2+)/Mn(2+)-dependent [corrected] protein serine/threonine phosphatase activity of Ppm1E and Ppm1F, but not that attributable to other PPM family members, including Ppm1A/PP2Cα. Depletion of Ppm1E, but not Ppm1A, using lentiviral-mediated stable gene silencing, increased AMPKα-Thr172 phosphorylation approximately three fold in HEK293 cells. In addition, incubation of cells with low concentrations of phenformin and depletion of Ppm1E increased AMPK phosphorylation synergistically. Ppm1E and the closely related Ppm1F interact weakly with AMPK and assays with lysates of cells stably depleted of Ppm1F suggest [corrected] that this phosphatase contributes to dephosphorylation of AMPK. The data indicate that Ppm1E and probably PpM1F are in cellulo AMPK phosphatases and that Ppm1E is a potential anti-diabetic drug target.
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Affiliation(s)
- Martin Voss
- Medical Research Council Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee, Scotland, UK
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Paterson J, Kelsall IR, Cohen PTW. Disruption of the striated muscle glycogen-targeting subunit of protein phosphatase 1: influence of the genetic background. J Mol Endocrinol 2008; 40:47-59. [PMID: 18234908 DOI: 10.1677/jme-07-0120] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A prediabetic phenotype of glucose intolerance, insulin resistance and obesity was observed at approximately 12 months of age in mice homozygous for a null allele of the major skeletal muscle glycogen-targeting subunit G(M) of protein phosphatase 1 (PP1) and derived from a 129/Ola donor strain. In this study, backcrossing of these G(M)-/- mice (termed obese G(M)-/- mice) onto two different genetic backgrounds gave rise to lean, glucose-tolerant, insulin-sensitive G(M)-/- mice (termed lean G(M)-/- mice), indicating that at least one variant gene in the 129/Ola background, not present in the C57BL/6 or 129s2/sV background, is required for the development of the prediabetic phenotype of obese mice. Slightly elevated AMP-activated protein kinase alpha2 activity in the skeletal muscle of lean C57BL/6 mice was also observed to a lesser extent in the obese G(M)-/- mice. Normal or slightly raised in vivo glucose transport in lean C57BL/6 G(M)-/- mice compared with decreased glucose transport in the obese G(M)-/- mice supports the tenet that adequate transport of glucose may be a key factor in preventing the development of the prediabetic phenotype. The pH 6.8/pH 8.6 activity ratio of phosphorylase kinase was increased in lean C57BL/6 G(M)-/- mice compared with controls indicating that phosphorylase kinase is an in vivo substrate of PP1-G(M).
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Affiliation(s)
- James Paterson
- Medical Research Council Protein Phosphorylation Unit, College of Life Sciences, Sir James Black Centre, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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Kelsall IR, Munro S, Hallyburton I, Treadway JL, Cohen PTW. The hepatic PP1 glycogen-targeting subunit interaction with phosphorylaseacan be blocked by C-terminal tyrosine deletion or an indole drug. FEBS Lett 2007; 581:4749-53. [PMID: 17870073 DOI: 10.1016/j.febslet.2007.08.073] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2007] [Revised: 08/28/2007] [Accepted: 08/29/2007] [Indexed: 11/16/2022]
Abstract
The inhibition of hepatic glycogen-associated protein phosphatase-1 (PP1-G(L)) by glycogen phosphorylase a prevents the dephosphorylation and activation of glycogen synthase, suppressing glycogen synthesis when glycogenolysis is activated. Here, we show that a peptide ((280)LGPYY(284)) comprising the last five amino acids of G(L) retains high-affinity interaction with phosphorylase a and that the two tyrosines play crucial roles. Tyr284 deletion abolishes binding of phosphorylase a to G(L) and replacement by phenylalanine is insufficient to restore high-affinity binding. We show that a phosphorylase inhibitor blocks the interaction of phosphorylase a with the G(L) C-terminus, suggesting that the latter interaction could be targeted to develop an anti-diabetic drug.
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Affiliation(s)
- Ian R Kelsall
- Medical Research Council, Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
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