1
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Cattin-Ortolá J, Kaufman JGG, Gillingham AK, Wagstaff JL, Peak-Chew SY, Stevens TJ, Boulanger J, Owen DJ, Munro S. Cargo selective vesicle tethering: The structural basis for binding of specific cargo proteins by the Golgi tether component TBC1D23. Sci Adv 2024; 10:eadl0608. [PMID: 38552021 DOI: 10.1126/sciadv.adl0608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 02/26/2024] [Indexed: 04/02/2024]
Abstract
The Golgi-localized golgins golgin-97 and golgin-245 capture transport vesicles arriving from endosomes via the protein TBC1D23. The amino-terminal domain of TBC1D23 binds to the golgins, and the carboxyl-terminal domain of TBC1D23 captures the vesicles, but how it recognizes specific vesicles was unclear. A search for binding partners of the carboxyl-terminal domain unexpectedly revealed direct binding to carboxypeptidase D and syntaxin-16, known cargo proteins of the captured vesicles. Binding is via a threonine-leucine-tyrosine (TLY) sequence present in both proteins next to an acidic cluster. A crystal structure reveals how this acidic TLY motif binds to TBC1D23. An acidic TLY motif is also present in the tails of other endosome-to-Golgi cargo, and these also bind TBC1D23. Structure-guided mutations in the carboxyl-terminal domain that disrupt motif binding in vitro also block vesicle capture in vivo. Thus, TBC1D23 attached to golgin-97 and golgin-245 captures vesicles by a previously undescribed mechanism: the recognition of a motif shared by cargo proteins carried by the vesicle.
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Affiliation(s)
- Jérôme Cattin-Ortolá
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Jonathan G G Kaufman
- Cambridge Institute for Medical Research, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Alison K Gillingham
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Jane L Wagstaff
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Sew-Yeu Peak-Chew
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Tim J Stevens
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Jérôme Boulanger
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - David J Owen
- Cambridge Institute for Medical Research, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Sean Munro
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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2
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Hu H, van Roon AMM, Ghanim GE, Ahsan B, Oluwole AO, Peak-Chew SY, Robinson CV, Nguyen THD. Structural basis of telomeric nucleosome recognition by shelterin factor TRF1. Sci Adv 2023; 9:eadi4148. [PMID: 37624885 PMCID: PMC10456876 DOI: 10.1126/sciadv.adi4148] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 07/26/2023] [Indexed: 08/27/2023]
Abstract
Shelterin and nucleosomes are the key players that organize mammalian chromosome ends into the protective telomere caps. However, how they interact with each other at telomeres remains unknown. We report cryo-electron microscopy structures of a human telomeric nucleosome both unbound and bound to the shelterin factor TRF1. Our structures reveal that TRF1 binds unwrapped nucleosomal DNA ends by engaging both the nucleosomal DNA and the histone octamer. Unexpectedly, TRF1 binding shifts the register of the nucleosomal DNA by 1 bp. We discovered that phosphorylation of the TRF1 C terminus and a noncanomical DNA binding surface on TRF1 are critical for its association with telomeric nucleosomes. These insights into shelterin-chromatin interactions have crucial implications for understanding telomeric chromatin organization and other roles of shelterin at telomeres including replication and transcription.
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Affiliation(s)
- Hongmiao Hu
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | | | | | - Bilal Ahsan
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Abraham O. Oluwole
- Department of Chemistry, University of Oxford, Oxford, OX1 3QZ UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, OX1 3QU UK
| | | | - Carol V. Robinson
- Department of Chemistry, University of Oxford, Oxford, OX1 3QZ UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, OX1 3QU UK
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3
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Yagita Y, Zavodszky E, Peak-Chew SY, Hegde RS. Mechanism of orphan subunit recognition during assembly quality control. Cell 2023; 186:3443-3459.e24. [PMID: 37480851 PMCID: PMC10501995 DOI: 10.1016/j.cell.2023.06.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 05/16/2023] [Accepted: 06/22/2023] [Indexed: 07/24/2023]
Abstract
Cells contain numerous abundant molecular machines assembled from multiple subunits. Imbalances in subunit production and failed assembly generate orphan subunits that are eliminated by poorly defined pathways. Here, we determined how orphan subunits of the cytosolic chaperonin CCT are recognized. Several unassembled CCT subunits recruited the E3 ubiquitin ligase HERC2 using ZNRD2 as an adaptor. Both factors were necessary for orphan CCT subunit degradation in cells, sufficient for CCT subunit ubiquitination with purified factors, and necessary for optimal cell fitness. Domain mapping and structure prediction defined the molecular features of a minimal HERC2-ZNRD2-CCT module. The structural model, whose key elements were validated in cells using point mutants, shows why ZNRD2 selectively recognizes multiple orphaned CCT subunits without engaging assembled CCT. Our findings reveal how failures during CCT assembly are monitored and provide a paradigm for the molecular recognition of orphan subunits, the largest source of quality control substrates in cells.
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Affiliation(s)
- Yuichi Yagita
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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4
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Höpfler M, Absmeier E, Peak-Chew SY, Vartholomaiou E, Passmore LA, Gasic I, Hegde RS. Mechanism of ribosome-associated mRNA degradation during tubulin autoregulation. Mol Cell 2023; 83:2290-2302.e13. [PMID: 37295431 PMCID: PMC10403363 DOI: 10.1016/j.molcel.2023.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 03/28/2023] [Accepted: 05/15/2023] [Indexed: 06/12/2023]
Abstract
Microtubules play crucial roles in cellular architecture, intracellular transport, and mitosis. The availability of free tubulin subunits affects polymerization dynamics and microtubule function. When cells sense excess free tubulin, they trigger degradation of the encoding mRNAs, which requires recognition of the nascent polypeptide by the tubulin-specific ribosome-binding factor TTC5. How TTC5 initiates the decay of tubulin mRNAs is unknown. Here, our biochemical and structural analysis reveals that TTC5 recruits the poorly studied protein SCAPER to the ribosome. SCAPER, in turn, engages the CCR4-NOT deadenylase complex through its CNOT11 subunit to trigger tubulin mRNA decay. SCAPER mutants that cause intellectual disability and retinitis pigmentosa in humans are impaired in CCR4-NOT recruitment, tubulin mRNA degradation, and microtubule-dependent chromosome segregation. Our findings demonstrate how recognition of a nascent polypeptide on the ribosome is physically linked to mRNA decay factors via a relay of protein-protein interactions, providing a paradigm for specificity in cytoplasmic gene regulation.
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Affiliation(s)
- Markus Höpfler
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Eva Absmeier
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Sew-Yeu Peak-Chew
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | | | - Lori A Passmore
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Ivana Gasic
- Department of Cell Biology, University of Geneva, Geneva, Switzerland
| | - Ramanujan S Hegde
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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5
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Böhning J, Dobbelstein AW, Sulkowski N, Eilers K, von Kügelgen A, Tarafder AK, Peak-Chew SY, Skehel M, Alva V, Filloux A, Bharat TAM. Architecture of the biofilm-associated archaic Chaperone-Usher pilus CupE from Pseudomonas aeruginosa. PLoS Pathog 2023; 19:e1011177. [PMID: 37058467 PMCID: PMC10104325 DOI: 10.1371/journal.ppat.1011177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 07/06/2022] [Accepted: 02/03/2023] [Indexed: 04/15/2023] Open
Abstract
Chaperone-Usher Pathway (CUP) pili are major adhesins in Gram-negative bacteria, mediating bacterial adherence to biotic and abiotic surfaces. While classical CUP pili have been extensively characterized, little is known about so-called archaic CUP pili, which are phylogenetically widespread and promote biofilm formation by several human pathogens. In this study, we present the electron cryomicroscopy structure of the archaic CupE pilus from the opportunistic human pathogen Pseudomonas aeruginosa. We show that CupE1 subunits within the pilus are arranged in a zigzag architecture, containing an N-terminal donor β-strand extending from each subunit into the next, where it is anchored by hydrophobic interactions, with comparatively weaker interactions at the rest of the inter-subunit interface. Imaging CupE pili on the surface of P. aeruginosa cells using electron cryotomography shows that CupE pili adopt variable curvatures in response to their environment, which might facilitate their role in promoting cellular attachment. Finally, bioinformatic analysis shows the widespread abundance of cupE genes in isolates of P. aeruginosa and the co-occurrence of cupE with other cup clusters, suggesting interdependence of cup pili in regulating bacterial adherence within biofilms. Taken together, our study provides insights into the architecture of archaic CUP pili, providing a structural basis for understanding their role in promoting cellular adhesion and biofilm formation in P. aeruginosa.
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Affiliation(s)
- Jan Böhning
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Adrian W. Dobbelstein
- Department of Protein Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Nina Sulkowski
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Kira Eilers
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Andriko von Kügelgen
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Abul K. Tarafder
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Sew-Yeu Peak-Chew
- Cell Biology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
| | - Mark Skehel
- Proteomics Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Vikram Alva
- Department of Protein Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Alain Filloux
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Tanmay A. M. Bharat
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- Structural Studies Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
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6
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Freund N, Taylor AI, Arangundy-Franklin S, Subramanian N, Peak-Chew SY, Whitaker AM, Freudenthal BD, Abramov M, Herdewijn P, Holliger P. A two-residue nascent-strand steric gate controls synthesis of 2'-O-methyl- and 2'-O-(2-methoxyethyl)-RNA. Nat Chem 2023; 15:91-100. [PMID: 36229679 PMCID: PMC7614059 DOI: 10.1038/s41557-022-01050-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [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: 09/24/2021] [Accepted: 08/29/2022] [Indexed: 01/17/2023]
Abstract
Steric exclusion is a key element of enzyme substrate specificity, including in polymerases. Such substrate specificity restricts the enzymatic synthesis of 2'-modified nucleic acids, which are of interest in nucleic-acid-based drug development. Here we describe the discovery of a two-residue, nascent-strand, steric control 'gate' in an archaeal DNA polymerase. We show that engineering of the gate to reduce steric bulk in the context of a previously described RNA polymerase activity unlocks the synthesis of 2'-modified RNA oligomers, specifically the efficient synthesis of both defined and random-sequence 2'-O-methyl-RNA (2'OMe-RNA) and 2'-O-(2-methoxyethyl)-RNA (MOE-RNA) oligomers up to 750 nt. This enabled the discovery of RNA endonuclease catalysts entirely composed of 2'OMe-RNA (2'OMezymes) for the allele-specific cleavage of oncogenic KRAS (G12D) and β-catenin CTNNB1 (S33Y) mRNAs, and the elaboration of mixed 2'OMe-/MOE-RNA aptamers with high affinity for vascular endothelial growth factor. Our results open up these 2'-modified RNAs-used in several approved nucleic acid therapeutics-for enzymatic synthesis and a wider exploration in directed evolution and nanotechnology.
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Affiliation(s)
- Niklas Freund
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Alexander I Taylor
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus, University of Cambridge, Cambridge, UK.
| | | | - Nithya Subramanian
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Sew-Yeu Peak-Chew
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Amy M Whitaker
- Laboratory of Genome Maintenance and Structural Biology, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
- Cancer Epigenetics Institute, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Bret D Freudenthal
- Laboratory of Genome Maintenance and Structural Biology, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Mikhail Abramov
- Medicinal Chemistry, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Piet Herdewijn
- Medicinal Chemistry, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Philipp Holliger
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
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7
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Taylor AI, Wan CJK, Donde MJ, Peak-Chew SY, Holliger P. A modular XNAzyme cleaves long, structured RNAs under physiological conditions and enables allele-specific gene silencing. Nat Chem 2022; 14:1295-1305. [PMID: 36064973 PMCID: PMC7613789 DOI: 10.1038/s41557-022-01021-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 07/08/2022] [Indexed: 11/07/2022]
Abstract
Nucleic-acid catalysts (ribozymes, DNA- and XNAzymes) cleave target (m)RNAs with high specificity but have shown limited efficacy in clinical applications. Here we report on the in vitro evolution and engineering of a highly specific modular RNA endonuclease XNAzyme, FR6_1, composed of 2'-deoxy-2'-fluoro-β-D-arabino nucleic acid (FANA). FR6_1 overcomes the activity limitations of previous DNA- and XNAzymes and can be retargeted to cleave highly structured full-length (>5 kb) BRAF and KRAS mRNAs at physiological Mg2+ concentrations with allelic selectivity for tumour-associated (BRAF V600E and KRAS G12D) mutations. Phosphorothioate-FANA modification enhances FR6_1 biostability and enables rapid KRAS mRNA knockdown in cultured human adenocarcinoma cells with a G12D-allele-specific component provided by in vivo XNAzyme cleavage activity. These results provide a starting point for the development of improved gene-silencing agents based on FANA or other XNA chemistries.
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Affiliation(s)
- Alexander I Taylor
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge, Cambridge, UK.
| | | | - Maria J Donde
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge, Cambridge, UK
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8
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Gomez-Navarro N, Maldutyte J, Poljak K, Peak-Chew SY, Orme J, Bisnett BJ, Lamb CH, Boyce M, Gianni D, Miller EA. Selective inhibition of protein secretion by abrogating receptor-coat interactions during ER export. Proc Natl Acad Sci U S A 2022; 119:e2202080119. [PMID: 35901214 PMCID: PMC9351455 DOI: 10.1073/pnas.2202080119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 06/01/2022] [Indexed: 01/03/2023] Open
Abstract
Protein secretion is an essential process that drives cell growth, movement, and communication. Protein traffic within the secretory pathway occurs via transport intermediates that bud from one compartment and fuse with a downstream compartment to deliver their contents. Here, we explore the possibility that protein secretion can be selectively inhibited by perturbing protein-protein interactions that drive capture into transport vesicles. Human proprotein convertase subtilisin/kexin type 9 (PCSK9) is a determinant of cholesterol metabolism whose secretion is mediated by a specific cargo adaptor protein, SEC24A. We map a series of protein-protein interactions between PCSK9, its endoplasmic reticulum (ER) export receptor SURF4, and SEC24A that mediate secretion of PCSK9. We show that the interaction between SURF4 and SEC24A can be inhibited by 4-phenylbutyrate (4-PBA), a small molecule that occludes a cargo-binding domain of SEC24. This inhibition reduces secretion of PCSK9 and additional SURF4 clients that we identify by mass spectrometry, leaving other secreted cargoes unaffected. We propose that selective small-molecule inhibition of cargo recognition by SEC24 is a potential therapeutic intervention for atherosclerosis and other diseases that are modulated by secreted proteins.
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Affiliation(s)
- Natalia Gomez-Navarro
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Julija Maldutyte
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Kristina Poljak
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Sew-Yeu Peak-Chew
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Jonathon Orme
- Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, CB2 0AA, United Kingdom
| | - Brittany J. Bisnett
- Department of Biochemistry, Duke University School of Medicine, Durham, NC27710, USA
| | - Caitlin H. Lamb
- Department of Biochemistry, Duke University School of Medicine, Durham, NC27710, USA
| | - Michael Boyce
- Department of Biochemistry, Duke University School of Medicine, Durham, NC27710, USA
| | - Davide Gianni
- Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, CB2 0AA, United Kingdom
| | - Elizabeth A. Miller
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
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9
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Welch LG, Peak-Chew SY, Begum F, Stevens TJ, Munro S. GOLPH3 and GOLPH3L are broad-spectrum COPI adaptors for sorting into intra-Golgi transport vesicles. J Cell Biol 2021; 220:e202106115. [PMID: 34473204 PMCID: PMC8421267 DOI: 10.1083/jcb.202106115] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [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: 06/18/2021] [Revised: 08/08/2021] [Accepted: 08/10/2021] [Indexed: 12/14/2022] Open
Abstract
The fidelity of Golgi glycosylation is, in part, ensured by compartmentalization of enzymes within the stack. The COPI adaptor GOLPH3 has been shown to interact with the cytoplasmic tails of a subset of Golgi enzymes and direct their retention. However, other mechanisms of retention, and other roles for GOLPH3, have been proposed, and a comprehensive characterization of the clientele of GOLPH3 and its paralogue GOLPH3L is lacking. GOLPH3's role is of particular interest as it is frequently amplified in several solid tumor types. Here, we apply two orthogonal proteomic methods to identify GOLPH3+3L clients and find that they act in diverse glycosylation pathways or have other roles in the Golgi. Binding studies, bioinformatics, and a Golgi retention assay show that GOLPH3+3L bind the cytoplasmic tails of their clients through membrane-proximal positively charged residues. Furthermore, deletion of GOLPH3+3L causes multiple defects in glycosylation. Thus, GOLPH3+3L are major COPI adaptors that impinge on most, if not all, of the glycosylation pathways of the Golgi.
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Affiliation(s)
| | | | | | | | - Sean Munro
- MRC Laboratory of Molecular Biology, Cambridge, UK
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10
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Zavodszky E, Peak-Chew SY, Juszkiewicz S, Narvaez AJ, Hegde RS. Identification of a quality-control factor that monitors failures during proteasome assembly. Science 2021; 373:998-1004. [PMID: 34446601 DOI: 10.1126/science.abc6500] [Citation(s) in RCA: 18] [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: 05/06/2020] [Revised: 06/22/2021] [Accepted: 07/15/2021] [Indexed: 12/11/2022]
Abstract
In eukaryotic cells, half of all proteins function as subunits within multiprotein complexes. Imbalanced synthesis of subunits leads to unassembled intermediates that must be degraded to minimize cellular toxicity. Here, we found that excess PSMC5, a subunit of the proteasome base, was targeted for degradation by the HERC1 ubiquitin ligase in mammalian cells. HERC1 identified unassembled PSMC5 by its cognate assembly chaperone PAAF1. Because PAAF1 only dissociates after assembly, HERC1 could also engage later assembly intermediates such as the PSMC4-PSMC5-PAAF1 complex. A missense mutant of HERC1 that causes neurodegeneration in mice was impaired in the recognition and ubiquitination of the PSMC5-PAAF1 complex. Thus, proteasome assembly factors can serve as adaptors for ubiquitin ligases to facilitate elimination of unassembled intermediates and maintain protein homeostasis.
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11
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Juszkiewicz S, Slodkowicz G, Lin Z, Freire-Pritchett P, Peak-Chew SY, Hegde RS. Ribosome collisions trigger cis-acting feedback inhibition of translation initiation. eLife 2020; 9:e60038. [PMID: 32657267 PMCID: PMC7381030 DOI: 10.7554/elife.60038] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 07/10/2020] [Indexed: 12/19/2022] Open
Abstract
Translation of aberrant mRNAs can cause ribosomes to stall, leading to collisions with trailing ribosomes. Collided ribosomes are specifically recognised by ZNF598 to initiate protein and mRNA quality control pathways. Here we found using quantitative proteomics of collided ribosomes that EDF1 is a ZNF598-independent sensor of ribosome collisions. EDF1 stabilises GIGYF2 at collisions to inhibit translation initiation in cis via 4EHP. The GIGYF2 axis acts independently of the ZNF598 axis, but each pathway's output is more pronounced without the other. We propose that the widely conserved and highly abundant EDF1 monitors the transcriptome for excessive ribosome density, then triggers a GIGYF2-mediated response to locally and temporarily reduce ribosome loading. Only when collisions persist is translation abandoned to initiate ZNF598-dependent quality control. This tiered response to ribosome collisions would allow cells to dynamically tune translation rates while ensuring fidelity of the resulting protein products.
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Affiliation(s)
- Szymon Juszkiewicz
- MRC Laboratory of Molecular Biology, Francis Crick AvenueCambridgeUnited Kingdom
| | - Greg Slodkowicz
- MRC Laboratory of Molecular Biology, Francis Crick AvenueCambridgeUnited Kingdom
| | - Zhewang Lin
- MRC Laboratory of Molecular Biology, Francis Crick AvenueCambridgeUnited Kingdom
| | | | - Sew-Yeu Peak-Chew
- MRC Laboratory of Molecular Biology, Francis Crick AvenueCambridgeUnited Kingdom
| | - Ramanujan S Hegde
- MRC Laboratory of Molecular Biology, Francis Crick AvenueCambridgeUnited Kingdom
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12
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Flynn SM, Chen C, Artan M, Barratt S, Crisp A, Nelson GM, Peak-Chew SY, Begum F, Skehel M, de Bono M. MALT-1 mediates IL-17 neural signaling to regulate C. elegans behavior, immunity and longevity. Nat Commun 2020; 11:2099. [PMID: 32350248 PMCID: PMC7190641 DOI: 10.1038/s41467-020-15872-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 03/26/2020] [Indexed: 12/27/2022] Open
Abstract
Besides pro-inflammatory roles, the ancient cytokine interleukin-17 (IL-17) modulates neural circuit function. We investigate IL-17 signaling in neurons, and the extent it can alter organismal phenotypes. We combine immunoprecipitation and mass spectrometry to biochemically characterize endogenous signaling complexes that function downstream of IL-17 receptors in C. elegans neurons. We identify the paracaspase MALT-1 as a critical output of the pathway. MALT1 mediates signaling from many immune receptors in mammals, but was not previously implicated in IL-17 signaling or nervous system function. C. elegans MALT-1 forms a complex with homologs of Act1 and IRAK and appears to function both as a scaffold and a protease. MALT-1 is expressed broadly in the C. elegans nervous system, and neuronal IL-17-MALT-1 signaling regulates multiple phenotypes, including escape behavior, associative learning, immunity and longevity. Our data suggest MALT1 has an ancient role modulating neural circuit function downstream of IL-17 to remodel physiology and behavior.
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Affiliation(s)
- Sean M Flynn
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Changchun Chen
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
- Umeå Center for Molecular Medicine, Wallenberg Center for Molecular Medicine, Umeå University, SE-901 87, Umeå, Sweden
| | - Murat Artan
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Stephen Barratt
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Alastair Crisp
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Geoffrey M Nelson
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, 02115, USA
| | - Sew-Yeu Peak-Chew
- Biological Mass Spectrometry and Proteomics, Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Farida Begum
- Biological Mass Spectrometry and Proteomics, Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Mark Skehel
- Biological Mass Spectrometry and Proteomics, Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Mario de Bono
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom.
- Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400, Klosterneuburg, Austria.
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Williams TD, Peak-Chew SY, Paschke P, Kay RR. Akt and SGK protein kinases are required for efficient feeding by macropinocytosis. J Cell Sci 2019; 132:jcs.224998. [PMID: 30617109 DOI: 10.1242/jcs.224998] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 12/19/2018] [Indexed: 12/20/2022] Open
Abstract
Macropinocytosis is an actin-driven process of large-scale and non-specific fluid uptake used for feeding by some cancer cells and the macropinocytosis model organism Dictyostelium discoideum In Dictyostelium, macropinocytic cups are organized by 'macropinocytic patches' in the plasma membrane. These contain activated Ras, Rac and phospholipid PIP3, and direct actin polymerization to their periphery. We show that a Dictyostelium Akt (PkbA) and an SGK (PkbR1) protein kinase act downstream of PIP3 and, together, are nearly essential for fluid uptake. This pathway enables the formation of larger macropinocytic patches and macropinosomes, thereby dramatically increasing fluid uptake. Through phosphoproteomics, we identify a RhoGAP, GacG, as a PkbA and PkbR1 target, and show that it is required for efficient macropinocytosis and expansion of macropinocytic patches. The function of Akt and SGK in cell feeding through control of macropinosome size has implications for cancer cell biology.
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Affiliation(s)
| | | | - Peggy Paschke
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
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14
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Abstract
Nanoscale objects of increasing complexity can be constructed from DNA or RNA. However, the scope of potential applications could be enhanced by expanding beyond the moderate chemical diversity of natural nucleic acids. Here, we explore the construction of nano-objects made entirely from alternative building blocks: synthetic genetic polymers not found in nature, also called xeno nucleic acids (XNAs). Specifically, we describe assembly of 70 kDa tetrahedra elaborated in four different XNA chemistries (2'-fluro-2'-deoxy-ribofuranose nucleic acid (2'F-RNA), 2'-fluoroarabino nucleic acids (FANA), hexitol nucleic acids (HNA), and cyclohexene nucleic acids (CeNA)), as well as mixed designs, and a ∼600 kDa all-FANA octahedron, visualised by electron microscopy. Our results extend the chemical scope for programmable nanostructure assembly, with implications for the design of nano-objects and materials with an expanded range of structural and physicochemical properties, including enhanced biostability.
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Affiliation(s)
- Alexander I Taylor
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
- Department of Biology/Centre for Applied Synthetic Biology, Concordia University, 7141 Rue Sherbrooke, Montreal, H4B 1R6, Canada.
| | - Fabienne Beuron
- Division of Structural Biology, The Institute of Cancer Research, Chester Beatty Laboratories), 237 Fulham Road, London, SW3 6JB, UK
| | - Sew-Yeu Peak-Chew
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Edward P Morris
- Division of Structural Biology, The Institute of Cancer Research, Chester Beatty Laboratories), 237 Fulham Road, London, SW3 6JB, UK
| | - Piet Herdewijn
- Rega Institute, KU Leuven, Minderbroedersstraat 10, 3000, Leuven, Belgium
- Institute of Systems and Synthetic Biology, Université Evry, 5 rue Henri Desbrueres, 91030, Evry Cedex, France
| | - Philipp Holliger
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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15
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Pinheiro VB, Taylor AI, Cozens C, Abramov M, Renders M, Zhang S, Chaput JC, Wengel J, Peak-Chew SY, McLaughlin SH, Herdewijn P, Holliger P. Synthetic genetic polymers capable of heredity and evolution. Science 2012; 336:341-4. [PMID: 22517858 PMCID: PMC3362463 DOI: 10.1126/science.1217622] [Citation(s) in RCA: 489] [Impact Index Per Article: 40.8] [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] [Indexed: 11/02/2022]
Abstract
Genetic information storage and processing rely on just two polymers, DNA and RNA, yet whether their role reflects evolutionary history or fundamental functional constraints is currently unknown. With the use of polymerase evolution and design, we show that genetic information can be stored in and recovered from six alternative genetic polymers based on simple nucleic acid architectures not found in nature [xeno-nucleic acids (XNAs)]. We also select XNA aptamers, which bind their targets with high affinity and specificity, demonstrating that beyond heredity, specific XNAs have the capacity for Darwinian evolution and folding into defined structures. Thus, heredity and evolution, two hallmarks of life, are not limited to DNA and RNA but are likely to be emergent properties of polymers capable of information storage.
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Affiliation(s)
- Vitor B. Pinheiro
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK
| | | | | | - Mikhail Abramov
- REGA Institute, Katholieke Universiteit Leuven, Minderbroederstraat 10, B 3000, Leuven, Belgium
| | - Marleen Renders
- REGA Institute, Katholieke Universiteit Leuven, Minderbroederstraat 10, B 3000, Leuven, Belgium
| | - Su Zhang
- Center for Evolutionary Medicine and Informatics, The Biodesign Institute at Arizona State University, 1001 S. McAllister Avenue, Tempe, AZ 85287-5301, USA
| | - John C. Chaput
- Center for Evolutionary Medicine and Informatics, The Biodesign Institute at Arizona State University, 1001 S. McAllister Avenue, Tempe, AZ 85287-5301, USA
| | - Jesper Wengel
- Nucleic Acid Center, Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Sew-Yeu Peak-Chew
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK
| | | | - Piet Herdewijn
- REGA Institute, Katholieke Universiteit Leuven, Minderbroederstraat 10, B 3000, Leuven, Belgium
| | - Philipp Holliger
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK
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16
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Connell E, Darios F, Broersen K, Gatsby N, Peak-Chew SY, Rickman C, Davletov B. Mechanism of arachidonic acid action on syntaxin-Munc18. EMBO Rep 2007; 8:414-9. [PMID: 17363971 PMCID: PMC1852766 DOI: 10.1038/sj.embor.7400935] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [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: 11/30/2006] [Revised: 01/23/2007] [Accepted: 01/29/2007] [Indexed: 12/19/2022] Open
Abstract
Syntaxin and Munc18 are, in tandem, essential for exocytosis in all eukaryotes. Recently, it was shown that Munc18 inhibition of neuronal syntaxin 1 can be overcome by arachidonic acid, indicating that this common second messenger acts to disrupt the syntaxin-Munc18 interaction. Here, we show that arachidonic acid can stimulate syntaxin 1 alone, indicating that it is syntaxin 1 that undergoes a structural change in the syntaxin 1-Munc18 complex. Arachidonic acid is incapable of dissociating Munc18 from syntaxin 1 and, crucially, Munc18 remains associated with syntaxin 1 after arachidonic-acid-induced syntaxin 1 binding to synaptosomal-associated protein 25 kDa (SNAP25). We also show that the same principle operates in the case of the ubiquitous syntaxin 3 isoform, highlighting the conserved nature of the mechanism of arachidonic acid action. Neuronal soluble N-ethyl maleimide sensitive factor attachment protein receptors (SNAREs) can be isolated from brain membranes in a complex with endogenous Munc18, consistent with a proposed function of Munc18 in vesicle docking and fusion.
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Affiliation(s)
- Emma Connell
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
| | - Frédéric Darios
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
| | - Kerensa Broersen
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
| | - Naomi Gatsby
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
| | - Sew-Yeu Peak-Chew
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
| | - Colin Rickman
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
| | - Bazbek Davletov
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
- Tel: +44 1223 402071; Fax: +44 1223 402310; E-mail:
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17
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Schmid EM, Ford MGJ, Burtey A, Praefcke GJK, Peak-Chew SY, Mills IG, Benmerah A, McMahon HT. Role of the AP2 beta-appendage hub in recruiting partners for clathrin-coated vesicle assembly. PLoS Biol 2007; 4:e262. [PMID: 16903783 PMCID: PMC1540706 DOI: 10.1371/journal.pbio.0040262] [Citation(s) in RCA: 188] [Impact Index Per Article: 11.1] [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: 04/19/2006] [Accepted: 06/06/2006] [Indexed: 11/19/2022] Open
Abstract
Adaptor protein complex 2 α and β-appendage domains act as hubs for the assembly of accessory protein networks involved in clathrin-coated vesicle formation. We identify a large repertoire of β-appendage interactors by mass spectrometry. These interact with two distinct ligand interaction sites on the β-appendage (the “top” and “side” sites) that bind motifs distinct from those previously identified on the α-appendage. We solved the structure of the β-appendage with a peptide from the accessory protein Eps15 bound to the side site and with a peptide from the accessory cargo adaptor β-arrestin bound to the top site. We show that accessory proteins can bind simultaneously to multiple appendages, allowing these to cooperate in enhancing ligand avidities that appear to be irreversible in vitro. We now propose that clathrin, which interacts with the β-appendage, achieves ligand displacement in vivo by self-polymerisation as the coated pit matures. This changes the interaction environment from liquid-phase, affinity-driven interactions, to interactions driven by solid-phase stability (“matricity”). Accessory proteins that interact solely with the appendages are thereby displaced to areas of the coated pit where clathrin has not yet polymerised. However, proteins such as β-arrestin (non-visual arrestin) and autosomal recessive hypercholesterolemia protein, which have direct clathrin interactions, will remain in the coated pits with their interacting receptors. Formation of clathrin-coated vesicles, important in endocytosis, relies on accessory proteins assembled by adaptor protein complex 2 (AP2). Here, mass spectrometry and crystallization identifies proteins recruited by AP2's β-appendage for this purpose.
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Affiliation(s)
- Eva M Schmid
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Marijn G. J Ford
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Anne Burtey
- Department of Infectious Diseases, Institut Cochin, Paris, France
| | - Gerrit J. K Praefcke
- Center for Molecular Medicine Cologne, Institute for Genetics, University of Cologne, Köln, Germany
| | - Sew-Yeu Peak-Chew
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Ian G Mills
- The Oncology Department, University of Cambridge Hutchison/MRC Cancer Research Centre, Cambridge, United Kingdom
| | | | - Harvey T McMahon
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
- * To whom correspondence should be addressed. E-mail:
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18
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Mittal R, Peak-Chew SY, McMahon HT. Acetylation of MEK2 and I kappa B kinase (IKK) activation loop residues by YopJ inhibits signaling. Proc Natl Acad Sci U S A 2006; 103:18574-9. [PMID: 17116858 PMCID: PMC1654131 DOI: 10.1073/pnas.0608995103] [Citation(s) in RCA: 223] [Impact Index Per Article: 12.4] [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] [Indexed: 01/04/2023] Open
Abstract
To overcome host defenses, bacterial pathogens of the genus Yersinia inject specific effector proteins into colonized mammalian cells. One such virulence factor, YopJ, inhibits the host inflammatory response and induces apoptosis of immune cells by blocking multiple signaling pathways, including the MAPK and NF-kappaB pathways. In this study, we show that YopJ exerts its deleterious effects by catalyzing the acetylation of two serine residues in the activation loop of the MAP kinase kinase, MEK2. This covalent modification prevents the phosphorylation of these serine residues that is required for activation of MEK2 and downstream signal propagation. We also show that YopJ causes acetylation of a threonine residue in the activation loop of both the alpha and beta subunits of the NF-kappaB pathway kinase, IKK. These results establish a hitherto uncharacterized mode of action for bacterial toxins and suggest the possibility that serine/threonine acetylation may occur even under nonpathogenic conditions and may be a widespread protein modification regulating protein function in eukaryotic cells.
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Affiliation(s)
- Rohit Mittal
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
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19
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Abstract
SNAP-25 (25 kDa synaptosome-associated protein) is found in cells that release neurotransmitters and hormones, and plays a central role in the fusion of secretory vesicles with the plasma membrane. SNAP-25 has been shown to interact specifically with syntaxin 1, a 35 kDa membrane protein, to mediate the fusion process. Here, we investigated whether other known syntaxin isoforms found at the plasma membrane can serve as binding partners for SNAP-25 in vivo. In our analysis, we employed rat phaeochromocytoma PC12 cells that are often used as a model of neuronal functions. We now show that these cells contain large amounts of SNAP-25, which interacts not only with syntaxin 1, but also with ubiquitous syntaxins 2, 3 and 4. The plasma membrane syntaxins appear to occupy complementary domains at the plasma membrane. In defined reactions, the ubiquitous plasma membrane syntaxin isoforms, when in binary complexes with SNAP-25, readily bound vesicular synaptobrevin to form SDS-resistant SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) complexes implicated in membrane fusion. However, vesicular synaptotagmin and cytosolic complexin, both implicated in the fusion process, exhibited differential ability to interact with the SNARE complexes formed by syntaxins 1-4, suggesting that the plasma membrane syntaxins may mediate vesicle fusion events with different properties.
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Affiliation(s)
- Mark Bajohrs
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, U.K
| | - Frédéric Darios
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, U.K
| | - Sew-Yeu Peak-Chew
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, U.K
| | - Bazbek Davletov
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, U.K
- To whom correspondence should be addressed (email )
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20
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Praefcke GJK, Ford MGJ, Schmid EM, Olesen LE, Gallop JL, Peak-Chew SY, Vallis Y, Babu MM, Mills IG, McMahon HT. Evolving nature of the AP2 alpha-appendage hub during clathrin-coated vesicle endocytosis. EMBO J 2004; 23:4371-83. [PMID: 15496985 PMCID: PMC526462 DOI: 10.1038/sj.emboj.7600445] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Accepted: 09/21/2004] [Indexed: 11/08/2022] Open
Abstract
Clathrin-mediated endocytosis involves the assembly of a network of proteins that select cargo, modify membrane shape and drive invagination, vesicle scission and uncoating. This network is initially assembled around adaptor protein (AP) appendage domains, which are protein interaction hubs. Using crystallography, we show that FxDxF and WVxF peptide motifs from synaptojanin bind to distinct subdomains on alpha-appendages, called 'top' and 'side' sites. Appendages use both these sites to interact with their binding partners in vitro and in vivo. Occupation of both sites simultaneously results in high-affinity reversible interactions with lone appendages (e.g. eps15 and epsin1). Proteins with multiple copies of only one type of motif bind multiple appendages and so will aid adaptor clustering. These clustered alpha(appendage)-hubs have altered properties where they can sample many different binding partners, which in turn can interact with each other and indirectly with clathrin. In the final coated vesicle, most appendage binding partners are absent and thus the functional status of the appendage domain as an interaction hub is temporal and transitory giving directionality to vesicle assembly.
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Affiliation(s)
| | - Marijn G J Ford
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Eva M Schmid
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Lene E Olesen
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Jennifer L Gallop
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Sew-Yeu Peak-Chew
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Yvonne Vallis
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - M Madan Babu
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Ian G Mills
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Harvey T McMahon
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
- Laboratory of Molecular Biology, Medical Research Council, Hills Road, Cambridge CB2 2QH, UK. Tel.: +44 1223 402311; Fax: +44 1223 402310; E-mail:
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21
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Lee MJ, Gergely F, Jeffers K, Peak-Chew SY, Raff JW. Msps/XMAP215 interacts with the centrosomal protein D-TACC to regulate microtubule behaviour. Nat Cell Biol 2001; 3:643-9. [PMID: 11433296 DOI: 10.1038/35083033] [Citation(s) in RCA: 221] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The XMAP215/ch-TOG/Msps family of microtubule-associated proteins (MAPs) promote microtubule growth in vitro and are concentrated at centrosomes in vivo. We show here that Msps (mini-spindles protein) interacts with the centrosomal protein D-TACC, and that this interaction strongly influences microtubule behaviour in Drosophila embryos. If D-TACC levels are reduced, Msps does not concentrate at the centrosomes efficiently and the centrosomal microtubules appear to be destabilized. If D-TACC levels are increased, both D-TACC and Msps accumulate around the centrosomes/spindle poles, and the centrosomal microtubules appear to be stabilized. We show that the interaction between D-TACC and Msps is evolutionarily conserved. We propose that D-TACC and Msps normally cooperate to stabilize centrosomal microtubules by binding to their minus ends and binding to their plus ends as they grow out from the centrosome.
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Affiliation(s)
- M J Lee
- Department of Genetics, Wellcome/CRC Institute, Tennis Court Road, Cambridge CB2 1QR, UK
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22
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Clayton GM, Peak-Chew SY, Evans RM, Schwabe JW. The structure of the ultraspiracle ligand-binding domain reveals a nuclear receptor locked in an inactive conformation. Proc Natl Acad Sci U S A 2001; 98:1549-54. [PMID: 11171988 PMCID: PMC29294 DOI: 10.1073/pnas.98.4.1549] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Ultraspiracle (USP) is the invertebrate homologue of the mammalian retinoid X receptor (RXR). RXR plays a uniquely important role in differentiation, development, and homeostasis through its ability to serve as a heterodimeric partner to many other nuclear receptors. RXR is able to influence the activity of its partner receptors through the action of the ligand 9-cis retinoic acid. In contrast to RXR, USP has no known high-affinity ligand and is thought to be a silent component in the heterodimeric complex with partner receptors such as the ecdysone receptor. Here we report the 2.4-A crystal structure of the USP ligand-binding domain. The structure shows that a conserved sequence motif found in dipteran and lepidopteran USPs, but not in mammalian RXRs, serves to lock USP in an inactive conformation. It also shows that USP has a large hydrophobic cavity, implying that there is almost certainly a natural ligand for USP. This cavity is larger than that seen previously for most other nuclear receptors. Intriguingly, this cavity has partial occupancy by a bound lipid, which is likely to resemble the natural ligand for USP.
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Affiliation(s)
- G M Clayton
- Medical Research Council, Laboratory of Molecular Biology, Cambridge CB2 2QH, United Kingdom
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Abstract
Cells lacking the GTPase Ypt6p have defects in intracellular traffic and are temperature sensitive. Their growth is severely impaired by additional mutation of IMH1, which encodes a non-essential Golgi-associated coiled-coil protein. A screen for mutants that, like ypt6, specifically impair the growth of imh1 cells led to the identification of RIC1. Ric1p forms a tight complex with a previously uncharacterized protein, Rgp1p. The Ric1p-Rgp1p complex binds Ypt6p in a nucleotide-dependent manner, and purified Ric1p-Rgp1 stimulates guanine nucleotide exchange on Ypt6p in vitro. Deletion of RIC1 or RGP1, like that of YPT6, blocks the recycling of the exocytic SNARE Snc1p from early endosomes to the Golgi and causes temperature-sensitive growth, but this defect can be relieved by overexpression of YPT6. Ric1p largely colocalizes with the late Golgi marker Sec7p. Ypt6p shows a similar distribution, but this is altered when RIC1 or RGP1 is mutated. We infer that the Ric1p-Rgp1p complex serves to activate Ypt6p on Golgi membranes by nucleotide exchange, and that this is required for efficient fusion of endosome-derived vesicles with the Golgi.
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Affiliation(s)
- S Siniossoglou
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
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Sazanov LA, Peak-Chew SY, Fearnley IM, Walker JE. Resolution of the membrane domain of bovine complex I into subcomplexes: implications for the structural organization of the enzyme. Biochemistry 2000; 39:7229-35. [PMID: 10852722 DOI: 10.1021/bi000335t] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Complex I (NADH:ubiquinone oxidoreductase) purified from bovine heart mitochondria was treated with the detergent N, N-dimethyldodecylamine N-oxide (LDAO). The enzyme dissociated into two known subcomplexes, Ialpha and Ibeta, containing mostly hydrophilic and hydrophobic subunits, and a previously undetected fragment referred to as Igamma. Subcomplex Igamma contains the hydrophobic subunits ND1, ND2, ND3, and ND4L which are encoded in the mitochondrial genome, and the nuclear-encoded subunit KFYI. During size-exclusion chromatography in the presence of LDAO, subcomplex Ialpha lost several subunits and formed another characterized subcomplex known as Ilambda. Similarly, subcomplex Ibeta dissociated into two smaller subcomplexes, one of which contains the hydrophobic subunits ND4 and ND5; subcomplex Igamma released a fragment containing ND1 and ND2. These results suggest that in the intact complex subunits ND1 and ND2 are likely to be in a different region of the membrane domain than subunits ND4 and ND5. The compositions of the various subcomplexes and fragments of complex I provide an organization of the subunits of the enzyme in the framework of the known low resolution structure of the enzyme.
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Affiliation(s)
- L A Sazanov
- Medical Research Council Dunn Human Nutrition Unit, Cambridge, UK
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