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McShan AC, Flores-Solis D, Sun Y, Garfinkle SE, Toor JS, Young MC, Sgourakis NG. Conformational plasticity of RAS Q61 family of neoepitopes results in distinct features for targeted recognition. Nat Commun 2023; 14:8204. [PMID: 38081856 PMCID: PMC10713829 DOI: 10.1038/s41467-023-43654-9] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 11/15/2023] [Indexed: 12/18/2023] Open
Abstract
The conformational landscapes of peptide/human leucocyte antigen (pHLA) protein complexes encompassing tumor neoantigens provide a rationale for target selection towards autologous T cell, vaccine, and antibody-based therapeutic modalities. Here, using complementary biophysical and computational methods, we characterize recurrent RAS55-64 Q61 neoepitopes presented by the common HLA-A*01:01 allotype. We integrate sparse NMR restraints with Rosetta docking to determine the solution structure of NRASQ61K/HLA-A*01:01, which enables modeling of other common RAS55-64 neoepitopes. Hydrogen/deuterium exchange mass spectrometry experiments alongside molecular dynamics simulations reveal differences in solvent accessibility and conformational plasticity across a panel of common Q61 neoepitopes that are relevant for recognition by immunoreceptors. Finally, we predict binding and provide structural models of NRASQ61K antigens spanning the entire HLA allelic landscape, together with in vitro validation for HLA-A*01:191, HLA-B*15:01, and HLA-C*08:02. Our work provides a basis to delineate the solution surface features and immunogenicity of clinically relevant neoepitope/HLA targets for cancer therapy.
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Affiliation(s)
- Andrew C McShan
- Center for Computational and Genomic Medicine, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Dr NW, Atlanta, GA, 30318, USA
| | - David Flores-Solis
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA, 95064, USA
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, 37075, Göttingen, Germany
| | - Yi Sun
- Center for Computational and Genomic Medicine, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Samuel E Garfinkle
- Center for Computational and Genomic Medicine, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jugmohit S Toor
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA, 95064, USA
- Immunology Research Program, Henry Ford Cancer Institute, Henry Ford Health, Detroit, MI, 48202, USA
| | - Michael C Young
- Center for Computational and Genomic Medicine, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Nikolaos G Sgourakis
- Center for Computational and Genomic Medicine, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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2
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Flores-Solis D, Lushpinskaia IP, Polyansky AA, Changiarath A, Boehning M, Mirkovic M, Walshe J, Pietrek LM, Cramer P, Stelzl LS, Zagrovic B, Zweckstetter M. Driving forces behind phase separation of the carboxy-terminal domain of RNA polymerase II. Nat Commun 2023; 14:5979. [PMID: 37749095 PMCID: PMC10519987 DOI: 10.1038/s41467-023-41633-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [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: 01/09/2023] [Accepted: 09/10/2023] [Indexed: 09/27/2023] Open
Abstract
Eukaryotic gene regulation and pre-mRNA transcription depend on the carboxy-terminal domain (CTD) of RNA polymerase (Pol) II. Due to its highly repetitive, intrinsically disordered sequence, the CTD enables clustering and phase separation of Pol II. The molecular interactions that drive CTD phase separation and Pol II clustering are unclear. Here, we show that multivalent interactions involving tyrosine impart temperature- and concentration-dependent self-coacervation of the CTD. NMR spectroscopy, molecular ensemble calculations and all-atom molecular dynamics simulations demonstrate the presence of diverse tyrosine-engaging interactions, including tyrosine-proline contacts, in condensed states of human CTD and other low-complexity proteins. We further show that the network of multivalent interactions involving tyrosine is responsible for the co-recruitment of the human Mediator complex and CTD during phase separation. Our work advances the understanding of the driving forces of CTD phase separation and thus provides the basis to better understand CTD-mediated Pol II clustering in eukaryotic gene transcription.
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Affiliation(s)
- David Flores-Solis
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, 35075, Göttingen, Germany
| | - Irina P Lushpinskaia
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, 35075, Göttingen, Germany
| | - Anton A Polyansky
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Campus Vienna Biocenter 5, 1030, Vienna, Austria
- University of Vienna, Center for Molecular Biology, Department of Structural and Computational Biology, Campus Vienna Biocenter 5, 1030, Vienna, Austria
| | - Arya Changiarath
- Faculty of Biology, Johannes Gutenberg University Mainz (JGU), Gresemundweg 2, 55128, Mainz, Germany
- KOMET1, Institute of Physics, Johannes Gutenberg University Mainz (JGU), Staudingerweg 9, 55099, Mainz, Germany
| | - Marc Boehning
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077, Göttingen, Germany
| | - Milana Mirkovic
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Campus Vienna Biocenter 5, 1030, Vienna, Austria
- University of Vienna, Center for Molecular Biology, Department of Structural and Computational Biology, Campus Vienna Biocenter 5, 1030, Vienna, Austria
| | - James Walshe
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077, Göttingen, Germany
| | - Lisa M Pietrek
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue Strasße 3, 60438, Frankfurt am Main, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077, Göttingen, Germany
| | - Lukas S Stelzl
- Faculty of Biology, Johannes Gutenberg University Mainz (JGU), Gresemundweg 2, 55128, Mainz, Germany
- KOMET1, Institute of Physics, Johannes Gutenberg University Mainz (JGU), Staudingerweg 9, 55099, Mainz, Germany
- Institute of Molecular Biology (IMB), 55128, Mainz, Germany
| | - Bojan Zagrovic
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Campus Vienna Biocenter 5, 1030, Vienna, Austria
- University of Vienna, Center for Molecular Biology, Department of Structural and Computational Biology, Campus Vienna Biocenter 5, 1030, Vienna, Austria
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, 35075, Göttingen, Germany.
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077, Göttingen, Germany.
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3
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Lushpinskaia IP, Flores-Solis D, Zweckstetter M. Structure and phase separation of the C-terminal domain of RNA polymerase II. Biol Chem 2023; 404:839-844. [PMID: 37331973 DOI: 10.1515/hsz-2023-0136] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 06/01/2023] [Indexed: 06/20/2023]
Abstract
The repetitive heptads in the C-terminal domain (CTD) of RPB1, the largest subunit of RNA Polymerase II (Pol II), play a critical role in the regulation of Pol II-based transcription. Recent findings on the structure of the CTD in the pre-initiation complex determined by cryo-EM and the novel phase separation properties of key transcription components offers an expanded mechanistic interpretation of the spatiotemporal distribution of Pol II during transcription. Current experimental evidence further suggests an exquisite balance between CTD's local structure and an array of multivalent interactions that drive phase separation of Pol II and thus shape its transcriptional activity.
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Affiliation(s)
- Irina P Lushpinskaia
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, D-35075 Göttingen, Germany
| | - David Flores-Solis
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, D-35075 Göttingen, Germany
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, D-35075 Göttingen, Germany
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, D-37077 Göttingen, Germany
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4
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Yu T, Flores-Solis D, Eastep GN, Becker S, Zweckstetter M. Phosphatidylserine-dependent structure of synaptogyrin remodels the synaptic vesicle membrane. Nat Struct Mol Biol 2023:10.1038/s41594-023-01004-9. [PMID: 37217654 DOI: 10.1038/s41594-023-01004-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 04/21/2023] [Indexed: 05/24/2023]
Abstract
Synaptic vesicles are small membrane-enclosed organelles that store neurotransmitters at presynaptic terminals. The uniform morphology of synaptic vesicles is important for brain function, because it enables the storage of well-defined amounts of neurotransmitters and thus reliable synaptic transmission. Here, we show that the synaptic vesicle membrane protein synaptogyrin cooperates with the lipid phosphatidylserine to remodel the synaptic vesicle membrane. Using NMR spectroscopy, we determine the high-resolution structure of synaptogyrin and identify specific binding sites for phosphatidylserine. We further show that phosphatidylserine binding changes the transmembrane structure of synaptogyrin and is critical for membrane bending and the formation of small vesicles. Cooperative binding of phosphatidylserine to both a cytoplasmic and intravesicular lysine-arginine cluster in synaptogyrin is required for the formation of small vesicles. Together with other synaptic vesicle proteins, synaptogyrin thus can sculpt the membrane of synaptic vesicles.
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Affiliation(s)
- Taekyung Yu
- German Center for Neurodegenerative Diseases (DZNE), Göttingen, Germany
| | | | - Gunnar N Eastep
- German Center for Neurodegenerative Diseases (DZNE), Göttingen, Germany
| | - Stefan Becker
- Department for NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Göttingen, Germany.
- Department for NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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5
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Flores-Solis D, Mendoza A, Rentería-González I, Casados-Vazquez LE, Trasviña-Arenas CH, Jiménez-Sandoval P, Benítez-Cardoza CG, Del Río-Portilla F, Brieba LG. Solution structure of the inhibitor of cysteine proteases 1 from Entamoeba histolytica reveals a possible auto regulatory mechanism. Biochim Biophys Acta Proteins Proteom 2020; 1868:140512. [PMID: 32731033 DOI: 10.1016/j.bbapap.2020.140512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 07/07/2020] [Accepted: 07/24/2020] [Indexed: 10/23/2022]
Abstract
The genome of Entamoeba histolytica encodes approximately 50 Cysteine Proteases (CPs) whose activity is regulated by two Inhibitors of Cysteine Proteases (ICPs), EhICP1 and EhICP2. The main difference between both EhICPs is the acquisition of a 17 N-terminal targeting signal in EhICP2 and three exposed cysteine residues in EhICP1. The three exposed cysteines in EhICP1 potentiate the formation of cross-linking species that drive heterogeneity. Here we solved the NMR structure of EhICP1 using a mutant protein without accessible cysteines. Our structural data shows that EhICP1 adopts an immunoglobulin fold composed of seven β-strands, and three solvent exposed loops that resemble the structures of EhICP2 and chagasin. EhICP1 and EhICP2 are able to inhibit the archetypical cysteine protease papain by intercalating their BC loops into the protease active site independently of the character of the residue (serine or threonine) responsible to interact with the active site of papain. EhICP1 and EhICP2 present signals of functional divergence as they clustered in different clades. Two of the three exposed cysteines in EhICP1 are located at the DE loop that intercalates into the CP substrate-binding cleft. We propose that the solvent exposed cysteines of EhICP1 play a role in regulating its inhibitory activity and that in oxidative conditions, the cysteines of EhICP1 react to form intra and intermolecular disulfide bonds that render an inactive inhibitor. EhICP2 is not subject to redox regulation, as this inhibitor does not contain a single cysteine residue. This proposed redox regulation may be related to the differential cellular localization between EhICP1 and EhICP2.
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Affiliation(s)
- David Flores-Solis
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Circuito exterior s/n, Coyoacán, Ciudad de Mexico 04510, Mexico
| | - Angeles Mendoza
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Circuito exterior s/n, Coyoacán, Ciudad de Mexico 04510, Mexico
| | - Itzel Rentería-González
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, km. 9.6 Libramiento Norte Carretera Irapuato-León, CP 36821 Irapuato, Guanajuato, Mexico
| | - Luz E Casados-Vazquez
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, km. 9.6 Libramiento Norte Carretera Irapuato-León, CP 36821 Irapuato, Guanajuato, Mexico
| | - Carlos H Trasviña-Arenas
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, km. 9.6 Libramiento Norte Carretera Irapuato-León, CP 36821 Irapuato, Guanajuato, Mexico
| | - Pedro Jiménez-Sandoval
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, km. 9.6 Libramiento Norte Carretera Irapuato-León, CP 36821 Irapuato, Guanajuato, Mexico
| | - Claudia G Benítez-Cardoza
- Laboratorio de Investigación Bioquímica, Programa Institucional en Biomedicina Molecular ENMyH-Instituto Politécnico Nacional, Guillermo Massieu Helguera No. 239, La Escalera Ticoman, 07320, D.F, Mexico
| | - Federico Del Río-Portilla
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Circuito exterior s/n, Coyoacán, Ciudad de Mexico 04510, Mexico.
| | - Luis G Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, km. 9.6 Libramiento Norte Carretera Irapuato-León, CP 36821 Irapuato, Guanajuato, Mexico.
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6
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Sgourakis N, McShan A, Natarajan K, Jiang J, Park J, Overall S, Toor JS, Kumirov V, Flores-Solis D, Badstubner M, Kovrigin EL, Bagshaw CR, Pallesen J, Procko E, Margulies DH. Getting in the groove: Editing of MHC-I antigen repertoires by molecular chaperones is governed by a network of protein dynamics. The Journal of Immunology 2019. [DOI: 10.4049/jimmunol.202.supp.177.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Molecular chaperones TAPBPR (TAP-binding protein related) and tapasin associate with class-I major histocompatibility complex (MHC-I) molecules to promote optimization (editing) of peptide cargo. Using solution NMR, we investigate the molecular mechanism of peptide exchange performed by the 90 kDa chaperone protein complex. We identify TAPBPR-induced conformational changes on conserved MHC-I surfaces, consistent with our independently determined X-ray structure of the empty complex. Conformational dynamics present in the empty MHC-I are stabilized by TAPBPR in a peptide-deficient complex, and become progressively dampened with increasing peptide occupancy. Incoming peptides are recognized by the chaperoned groove according to the global stability of the final pMHC-I product, and anneal in a native-like conformation. Our results demonstrate an inverse relationship between MHC-I occupancy by peptide and the affinity of TAPBPR for such pMHC-I molecules, where the lifetime of transiently bound peptides controls the dynamic regulation of a conformational switch, located near the TAPBPR binding site, which triggers TAPBPR release. We further discuss the role of protein dynamics in shaping chaperone specificity towards different human and murine class-I MHC allotypes, and present the high-resolution cryoEM structure of a human A*02/TAPBPR complex with novel insights into the antigen editing mechanism. These results suggest a similar mechanism for the editing function of tapasin in the peptide-loading complex, and provide a molecular blueprint for the design of novel chaperones with tailored antigen editing functions.
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Affiliation(s)
| | | | - Kannan Natarajan
- 2National Institute of Allergy and Infectious Diseases, National Institutes of Health
| | - Jiansheng Jiang
- 2National Institute of Allergy and Infectious Diseases, National Institutes of Health
| | - Jihye Park
- 3university of Illinois at Urbana-Champaign
| | | | | | | | | | | | | | | | | | | | - David H Margulies
- 2National Institute of Allergy and Infectious Diseases, National Institutes of Health
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7
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McShan AC, Natarajan K, Kumirov VK, Flores-Solis D, Jiang J, Badstübner M, Toor JS, Bagshaw CR, Kovrigin EL, Margulies DH, Sgourakis NG. Peptide exchange on MHC-I by TAPBPR is driven by a negative allostery release cycle. Nat Chem Biol 2018; 14:811-820. [PMID: 29988068 PMCID: PMC6202177 DOI: 10.1038/s41589-018-0096-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [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: 10/12/2017] [Revised: 05/02/2018] [Accepted: 05/21/2018] [Indexed: 01/09/2023]
Abstract
Chaperones TAPBPR and tapasin associate with class-I major histocompatibility complexes (MHC-I) to promote optimization (editing) of peptide cargo. Here, we use solution NMR to investigate the mechanism of peptide exchange. We identify TAPBPR-induced conformational changes on conserved MHC-I molecular surfaces, consistent with our independently determined X-ray structure of the complex. Dynamics present in the empty MHC-I are stabilized by TAPBPR, and become progressively dampened with increasing peptide occupancy. Incoming peptides are recognized according to the global stability of the final pMHC-I product, and anneal in a native-like conformation to be edited by TAPBPR. Our results demonstrate an inverse relationship between MHC-I peptide occupancy and TAPBPR binding affinity, where the lifetime and structural features of transiently bound peptides controls the regulation of a conformational switch, located near the TAPBPR binding site, which triggers TAPBPR release. These results suggest a similar mechanism for the function of tapasin in the peptide-loading complex.
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Affiliation(s)
- Andrew C McShan
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Kannan Natarajan
- Molecular Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MA, USA
| | - Vlad K Kumirov
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - David Flores-Solis
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Jiansheng Jiang
- Molecular Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MA, USA
| | - Mareike Badstübner
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Jugmohit S Toor
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Clive R Bagshaw
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | | | - David H Margulies
- Molecular Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MA, USA
| | - Nikolaos G Sgourakis
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA.
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8
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Sgourakis N, McShan AC, Natarajan K, Kumirov VK, Flores-Solis D, Jiang J, Badstuebner M, Kovrigin EL, Margulies DH. Chaperone-assisted peptide exchange on MHC-I is driven by a negative allostery release cycle: Implications for a role of peptide-editing Molecular Chaperones in scrutinizing the peptide repertoire. The Journal of Immunology 2018. [DOI: 10.4049/jimmunol.200.supp.99.23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Molecular chaperones TAPBPR (TAP-binding protein related) and tapasin associate with major histocompatibility complex class I (MHC-I) to promote the loading of antigenic peptides through a poorly understood mechanism. Here, we use solution Nuclear Magnetic Resonance (NMR) spectroscopy to probe TAPBPR-induced changes on MHC-I. Dynamic motions present in the empty MHC groove become progressively dampened with increasing peptide occupancy, while allosteric communication between the A- and F-pockets regulates a conformational switch located near the TAPBPR binding site, which is crucial for chaperone release from the complex. Our analysis of NMR data recorded for a range of TAPBPR complexes prepared with both murine H2 and human HLA alleles complements the recent X-ray structures to provide atomic-resolution mechanistic insights into the selection of optimal peptide sequences for the displayed antigen repertoire. In particular, our results show that negative allosteric coupling between the MHC groove and chaperone binding sites allows TAPBPR to proofread MHC molecules containing a range of different peptides. Since the affinity of incoming peptides for the empty groove is greatly reduced in the chaperone complex, (micromolar range, relative to nanomolar for the free MHC), these interactions can provide a mechanism for optimizing the peptide repertoire, where only the highest-affinity peptides can drive chaperone release. Finally, our results suggest that TAPBPR may promote the dissociation of tightly bound peptides from MHC molecules, thereby further scrutinizing the displayed repertoire. These findings imply a similar mechanism for the specificity and editing function of tapasin in the peptide-loading complex.
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Flores-Solis D, Toledano Y, Rodríguez-Lima O, Cano-Sánchez P, Ramírez-Cordero BE, Landa A, Rodríguez de la Vega RC, del Rio-Portilla F. Solution structure and antiparasitic activity of scorpine-like peptides fromHoffmannihadrurus gertschi. FEBS Lett 2016; 590:2286-96. [DOI: 10.1002/1873-3468.12255] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 11/06/2022]
Affiliation(s)
- David Flores-Solis
- Departamento de Química de Biomacromoléculas; Instituto de Química; Universidad Nacional Autónoma de México, CU; Ciudad de México México
| | - Yanis Toledano
- Departamento de Química de Biomacromoléculas; Instituto de Química; Universidad Nacional Autónoma de México, CU; Ciudad de México México
- Departamento de Química Inorgánica y Nuclear; Facultad de Química; Universidad Nacional Autónoma de México, CU; Ciudad de México México
| | - Oscar Rodríguez-Lima
- Departamento de Microbiología y Parasitología; Facultad de Medicina; Universidad Nacional Autónoma de México, CU; Ciudad de México México
| | - Patricia Cano-Sánchez
- Departamento de Química de Biomacromoléculas; Instituto de Química; Universidad Nacional Autónoma de México, CU; Ciudad de México México
| | - Belen Ernestina Ramírez-Cordero
- División de Neurociencias; Departamento de Neuropatología Molecular; Instituto de Fisiología Celular; Universidad Nacional Autónoma de México, CU; Ciudad de México México
| | - Abraham Landa
- Departamento de Microbiología y Parasitología; Facultad de Medicina; Universidad Nacional Autónoma de México, CU; Ciudad de México México
| | | | - Federico del Rio-Portilla
- Departamento de Química de Biomacromoléculas; Instituto de Química; Universidad Nacional Autónoma de México, CU; Ciudad de México México
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10
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Ramírez-Cordero B, Toledano Y, Cano-Sánchez P, Hernández-López R, Flores-Solis D, Saucedo-Yáñez AL, Chávez-Uribe I, Brieba LG, del Río-Portilla F. Cytotoxicity of recombinant tamapin and related toxin-like peptides on model cell lines. Chem Res Toxicol 2014; 27:960-7. [PMID: 24821061 DOI: 10.1021/tx4004193] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The scorpion toxin tamapin displays the most potent and selective blockage against KCa2.2 channels known to date. In this work, we report the biosynthesis, three-dimensional structure, and cytotoxicity on cancer cell lines (Jurkat E6-1 and human mammary breast cancer MDA-MB-231) of recombinant tamapin and five related peptides bearing mutations on residues (R6A,R7A, R13A, R6A-R7A, and GS-tamapin) that were previously suggested to be important for tamapin's activity. The indicated cell lines were used as they constitutively express KCa2.2 channels. The studied toxin-like peptides displayed lethal responses on Jurkat T cells and breast cancer cells; their effect is dose- and time-dependent with IC50 values in the nanomolar range. The order of potency is r-tamapin>GS-tamapin>R6A>R13A>R6A-R7A>R7A for Jurkat T cells and r-tamapin>R7A for MDA-MB-231 breast cancer cells. Our structural determination by NMR demonstrated that r-tamapin preserves the folding of the αKTx5 subfamily and that neither single nor double alanine mutations affect the three-dimensional structure of the wild-type peptide. In contrast, our activity assays show that changes in cytotoxicity are related to the chemical nature of certain residues. Our results suggest that the toxic activity of r-tamapin on Jurkat and breast cancer cells could be mediated by the interaction of charged residues in tamapin with KCa2.2 channels via the apoptotic cell death pathway.
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Affiliation(s)
- Belén Ramírez-Cordero
- Instituto de Química, Universidad Nacional Autónoma de México , Ciudad Universitaria, Circuito Exterior s/n, México, D.F. 04510, México
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Saucedo AL, Flores-Solis D, Rodríguez de la Vega RC, Ramírez-Cordero B, Hernández-López R, Cano-Sánchez P, Noriega Navarro R, García-Valdés J, Coronas-Valderrama F, de Roodt A, Brieba LG, Domingos Possani L, del Río-Portilla F. New tricks of an old pattern: structural versatility of scorpion toxins with common cysteine spacing. J Biol Chem 2012; 287:12321-30. [PMID: 22238341 DOI: 10.1074/jbc.m111.329607] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Scorpion venoms are a rich source of K(+) channel-blocking peptides. For the most part, they are structurally related small disulfide-rich proteins containing a conserved pattern of six cysteines that is assumed to dictate their common three-dimensional folding. In the conventional pattern, two disulfide bridges connect an α-helical segment to the C-terminal strand of a double- or triple-stranded β-sheet, conforming a cystine-stabilized α/β scaffold (CSα/β). Here we show that two K(+) channel-blocking peptides from Tityus scorpions conserve the cysteine spacing of common scorpion venom peptides but display an unconventional disulfide pattern, accompanied by a complete rearrangement of the secondary structure topology into a CS helix-loop-helix fold. Sequence and structural comparisons of the peptides adopting this novel fold suggest that it would be a new elaboration of the widespread CSα/β scaffold, thus revealing an unexpected structural versatility of these small disulfide-rich proteins. Acknowledgment of such versatility is important to understand how venom structural complexity emerged on a limited number of molecular scaffolds.
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Affiliation(s)
- Alma Leticia Saucedo
- Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, D.F., 04510, México
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