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Sanches K, Ashwood LM, Olushola-Siedoks AAM, Wai DCC, Rahman A, Shakeel K, Naseem MU, Panyi G, Prentis PJ, Norton RS. Structure-function relationships in ShKT domain peptides: ShKT-Ts1 from the sea anemone Telmatactis stephensoni. Proteins 2024; 92:192-205. [PMID: 37794633 DOI: 10.1002/prot.26594] [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: 05/07/2023] [Revised: 08/14/2023] [Accepted: 09/07/2023] [Indexed: 10/06/2023]
Abstract
Diverse structural scaffolds have been described in peptides from sea anemones, with the ShKT domain being a common scaffold first identified in ShK toxin from Stichodactyla helianthus. ShK is a potent blocker of voltage-gated potassium channels (KV 1.x), and an analog, ShK-186 (dalazatide), has completed Phase 1 clinical trials in plaque psoriasis. The ShKT domain has been found in numerous other species, but only a tiny fraction of ShKT domains has been characterized functionally. Despite adopting the canonical ShK fold, some ShKT peptides from sea anemones inhibit KV 1.x, while others do not. Mutagenesis studies have shown that a Lys-Tyr (KY) dyad plays a key role in KV 1.x blockade, although a cationic residue followed by a hydrophobic residue may also suffice. Nevertheless, ShKT peptides displaying an ShK-like fold and containing a KY dyad do not necessarily block potassium channels, so additional criteria are needed to determine whether new ShKT peptides might show activity against potassium channels. In this study, we used a combination of NMR and molecular dynamics (MD) simulations to assess the potential activity of a new ShKT peptide. We determined the structure of ShKT-Ts1, from the sea anemone Telmatactis stephensoni, examined its tissue localization, and investigated its activity against a range of ion channels. As ShKT-Ts1 showed no activity against KV 1.x channels, we used MD simulations to investigate whether solvent exposure of the dyad residues may be informative in rationalizing and potentially predicting the ability of ShKT peptides to block KV 1.x channels. We show that either a buried dyad that does not become exposed during MD simulations, or a partially exposed dyad that becomes buried during MD simulations, correlates with weak or absent activity against KV 1.x channels. Therefore, structure determination coupled with MD simulations, may be used to predict whether new sequences belonging to the ShKT family may act as potassium channel blockers.
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Affiliation(s)
- Karoline Sanches
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, Australia
| | - Lauren M Ashwood
- School of Biology and Environmental Science, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, Australia
| | | | - Dorothy C C Wai
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Arfatur Rahman
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Kashmala Shakeel
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Peter J Prentis
- School of Biology and Environmental Science, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, Australia
- Centre for Agriculture and the Bioeconomy, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, Australia
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Chandy KG, Sanches K, Norton RS. Structure of the voltage-gated potassium channel K V1.3: Insights into the inactivated conformation and binding to therapeutic leads. Channels (Austin) 2023; 17:2253104. [PMID: 37695839 PMCID: PMC10496531 DOI: 10.1080/19336950.2023.2253104] [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] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/23/2023] [Accepted: 08/24/2023] [Indexed: 09/13/2023] Open
Abstract
The voltage-gated potassium channel KV1.3 is an important therapeutic target for the treatment of autoimmune and neuroinflammatory diseases. The recent structures of KV1.3, Shaker-IR (wild-type and inactivating W434F mutant) and an inactivating mutant of rat KV1.2-KV2.1 paddle chimera (KVChim-W362F+S367T+V377T) reveal that the transition of voltage-gated potassium channels from the open-conducting conformation into the non-conducting inactivated conformation involves the rupture of a key intra-subunit hydrogen bond that tethers the selectivity filter to the pore helix. Breakage of this bond allows the side chains of residues at the external end of the selectivity filter (Tyr447 and Asp449 in KV1.3) to rotate outwards, dilating the outer pore and disrupting ion permeation. Binding of the peptide dalazatide (ShK-186) and an antibody-ShK fusion to the external vestibule of KV1.3 narrows and stabilizes the selectivity filter in the open-conducting conformation, although K+ efflux is blocked by the peptide occluding the pore through the interaction of ShK-Lys22 with the backbone carbonyl of KV1.3-Tyr447 in the selectivity filter. Electrophysiological studies on ShK and the closely-related peptide HmK show that ShK blocks KV1.3 with significantly higher potency, even though molecular dynamics simulations show that ShK is more flexible than HmK. Binding of the anti-KV1.3 nanobody A0194009G09 to the turret and residues in the external loops of the voltage-sensing domain enhances the dilation of the outer selectivity filter in an exaggerated inactivated conformation. These studies lay the foundation to further define the mechanism of slow inactivation in KV channels and can help guide the development of future KV1.3-targeted immuno-therapeutics.
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Affiliation(s)
- K. George Chandy
- LKCMedicine-ICESing Ion Channel Platform, Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Karoline Sanches
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, Australia
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, Australia
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3
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Sanches K, Prypoten V, Chandy KG, Chalmers DK, Norton RS. Interaction of the Inhibitory Peptides ShK and HmK with the Voltage-Gated Potassium Channel K V1.3: Role of Conformational Dynamics. J Chem Inf Model 2023; 63:3043-3053. [PMID: 37143234 DOI: 10.1021/acs.jcim.2c01237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Peptide toxins that adopt the ShK fold can inhibit the voltage-gated potassium channel KV1.3 with IC50 values in the pM range and are therefore potential leads for drugs targeting autoimmune and neuroinflammatory diseases. Nuclear magnetic resonance (NMR) relaxation measurements and pressure-dependent NMR have shown that, despite being cross-linked by disulfide bonds, ShK itself is flexible in solution. This flexibility affects the local structure around the pharmacophore for the KV1.3 channel blockade and, in particular, the relative orientation of the key Lys and Tyr side chains (Lys22 and Tyr23 in ShK) and has implications for the design of KV1.3 inhibitors. In this study, we have performed molecular dynamics (MD) simulations on ShK and a close homologue, HmK, to probe the conformational space occupied by the Lys and Tyr residues, and docked the different conformations with a recently determined cryo-EM structure of the KV1.3 channel. Although ShK and HmK have 60% sequence identity, their dynamic behaviors are quite different, with ShK sampling a broad range of conformations over the course of a 5 μs MD simulation, while HmK is relatively rigid. We also investigated the importance of conformational dynamics, in particular the distance between the side chains of the key dyad Lys22 and Tyr23, for binding to KV1.3. Although these peptides have quite different dynamics, the dyad in both adopts a similar configuration upon binding, revealing a conformational selection upon binding to KV1.3 in the case of ShK. Both peptides bind to KV1.3 with Lys22 occupying the pore of the channel. Intriguingly, the more flexible peptide, ShK, binds with significantly higher affinity than HmK.
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Affiliation(s)
- Karoline Sanches
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria 3052, Australia
| | - Viktor Prypoten
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - K George Chandy
- LKCMedicine-ICESing Ion Channel Platform, Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore 636921, Singapore
| | - David K Chalmers
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria 3052, Australia
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4
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Almeida FCL, Sanches K, Caruso IP, Melo FA. NMR Relaxation Dispersion Experiments to Study Phosphopeptide Recognition by SH2 Domains: The Grb2-SH2-Phosphopeptide Encounter Complex. Methods Mol Biol 2023; 2705:135-151. [PMID: 37668973 DOI: 10.1007/978-1-0716-3393-9_8] [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] [Indexed: 09/06/2023]
Abstract
Protein interactions are at the essence of life. Proteins evolved not to have stable structures, but rather to be specialized in participating in a network of interactions. Every interaction involving proteins comprises the formation of an encounter complex, which may have two outcomes: (i) the dissociation or (ii) the formation of the final specific complex. Here, we present a methodology to characterize the encounter complex of the Grb2-SH2 domain with a phosphopeptide. This method can be generalized to other protein partners. It consists of the measurement of 15N CPMG relaxation dispersion (RD) profiles of the protein in the free state, which describes the residues that are in conformational exchange. We then acquire the dispersion profiles of the protein at a semisaturated concentration of the ligand. At this condition, the chemical exchange between the free and bound state leads to the observation of dispersion profiles in residues that are not in conformational exchange in the free state. This is due to fuzzy interactions that are typical of the encounter complexes. The transient "touching" of the ligand in the protein partner generates these new relaxation dispersion profiles. For the Grb2-SH2 domain, we observed a wider surface at SH2 for the encounter complex than the phosphopeptide (pY) binding site, which might explain the molecular recognition of remote phosphotyrosine. The Grb2-SH2-pY encounter complex is dominated by electrostatic interactions, which contribute to the fuzziness of the complex, but also have contribution of hydrophobic interactions.
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Affiliation(s)
- Fabio C L Almeida
- National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
- Institute of Medical Biochemistry - IBqM, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Karoline Sanches
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, VIC, Australia
| | - Icaro P Caruso
- National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), Sao Jose do Rio Preto, Sao Paulo, Brazil
| | - Fernando A Melo
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), Sao Jose do Rio Preto, Sao Paulo, Brazil
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Caruso IP, dos Santos Almeida V, do Amaral MJ, de Andrade GC, de Araújo GR, de Araújo TS, de Azevedo JM, Barbosa GM, Bartkevihi L, Bezerra PR, dos Santos Cabral KM, de Lourenço IO, Malizia-Motta CL, de Luna Marques A, Mebus-Antunes NC, Neves-Martins TC, de Sá JM, Sanches K, Santana-Silva MC, Vasconcelos AA, da Silva Almeida M, de Amorim GC, Anobom CD, Da Poian AT, Gomes-Neto F, Pinheiro AS, Almeida FC. Insights into the specificity for the interaction of the promiscuous SARS-CoV-2 nucleocapsid protein N-terminal domain with deoxyribonucleic acids. Int J Biol Macromol 2022; 203:466-480. [PMID: 35077748 PMCID: PMC8783401 DOI: 10.1016/j.ijbiomac.2022.01.121] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [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: 10/31/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/23/2022]
Abstract
The SARS-CoV-2 nucleocapsid protein (N) is a multifunctional promiscuous nucleic acid-binding protein, which plays a major role in nucleocapsid assembly and discontinuous RNA transcription, facilitating the template switch of transcriptional regulatory sequences (TRS). Here, we dissect the structural features of the N protein N-terminal domain (N-NTD) and N-NTD plus the SR-rich motif (N-NTD-SR) upon binding to single and double-stranded TRS DNA, as well as their activities for dsTRS melting and TRS-induced liquid-liquid phase separation (LLPS). Our study gives insights on the specificity for N-NTD(-SR) interaction with TRS. We observed an approximation of the triple-thymidine (TTT) motif of the TRS to β-sheet II, giving rise to an orientation difference of ~25° between dsTRS and non-specific sequence (dsNS). It led to a local unfavorable energetic contribution that might trigger the melting activity. The thermodynamic parameters of binding of ssTRSs and dsTRS suggested that the duplex dissociation of the dsTRS in the binding cleft is entropically favorable. We showed a preference for TRS in the formation of liquid condensates when compared to NS. Moreover, our results on DNA binding may serve as a starting point for the design of inhibitors, including aptamers, against N, a possible therapeutic target essential for the virus infectivity.
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Affiliation(s)
- Icaro Putinhon Caruso
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São José do Rio Preto, Brazil; Rio BioNMR Network, Rio de Janeiro, Brazil.
| | - Vitor dos Santos Almeida
- National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Mariana Juliani do Amaral
- Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Protein Advanced Biochemistry (PAB), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Guilherme Caldas de Andrade
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Gabriela Rocha de Araújo
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Talita Stelling de Araújo
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Protein Advanced Biochemistry (PAB), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Jéssica Moreira de Azevedo
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Protein Advanced Biochemistry (PAB), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Glauce Moreno Barbosa
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Leonardo Bartkevihi
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Peter Reis Bezerra
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Katia Maria dos Santos Cabral
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Protein Advanced Biochemistry (PAB), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Isabella Otênio de Lourenço
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São José do Rio Preto, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Clara L.F. Malizia-Motta
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Aline de Luna Marques
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Multidisciplinary Center for Research in Biology (NUMPEX), Campus Duque de Caxias Federal University of Rio de Janeiro, Duque de Caxias, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Nathane Cunha Mebus-Antunes
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Thais Cristtina Neves-Martins
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Jéssica Maróstica de Sá
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São José do Rio Preto, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Karoline Sanches
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São José do Rio Preto, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Marcos Caique Santana-Silva
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Multidisciplinary Center for Research in Biology (NUMPEX), Campus Duque de Caxias Federal University of Rio de Janeiro, Duque de Caxias, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Ariana Azevedo Vasconcelos
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Marcius da Silva Almeida
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Protein Advanced Biochemistry (PAB), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Gisele Cardoso de Amorim
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Multidisciplinary Center for Research in Biology (NUMPEX), Campus Duque de Caxias Federal University of Rio de Janeiro, Duque de Caxias, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Cristiane Dinis Anobom
- National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Andrea T. Da Poian
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Francisco Gomes-Neto
- National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Laboratory of Toxinology, Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Anderson S. Pinheiro
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil
| | - Fabio C.L. Almeida
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil,Rio BioNMR Network, Rio de Janeiro, Brazil,Correspondence to: F.C.L. Almeida, National Center of Nuclear Magnetic Resonance (CNRMN), CENABIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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6
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Sanches K, Wai DCC, Norton RS. Conformational dynamics in peptide toxins: Implications for receptor interactions and molecular design. Toxicon 2021; 201:127-140. [PMID: 34454969 DOI: 10.1016/j.toxicon.2021.08.020] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/19/2021] [Accepted: 08/23/2021] [Indexed: 10/20/2022]
Abstract
Peptide toxins are potent and often exquisitely selective probes of the structure and function of ion channels and receptors, and are therefore of significant interest to the pharmaceutical and biotech industries as both pharmacological tools and therapeutic leads. The three-dimensional structures of peptide toxins are essential as a basis for understanding their structure-activity relationships and their binding to target receptors, as well as in guiding the design of analogues with modified potency and/or selectivity for key targets. NMR spectroscopy has played a key role in elucidating the structures of peptide toxins and probing their structure-function relationships. In this article, we highlight the additional important contribution of NMR to characterising the dynamics of peptide toxins. We also compare the information available from NMR measurements with that afforded by molecular dynamics simulations. We describe several examples of the importance of dynamics measurements over a range of timescales for understanding the structure-function relationships of peptide toxins and their receptor engagement. Peptide toxins that inhibit the voltage-gated potassium channel KV1.3 with pM affinities display different degrees of conformational flexibility, even though they contain multiple disulfide bonds, and this flexibility can affect the relative orientation of residues that have been shown to be critical for channel binding. Information on the dynamic properties of peptide toxins is important in the design of analogues or mimetics where receptor-bound structures are not available.
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Affiliation(s)
- Karoline Sanches
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia; ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, 3052, Australia
| | - Dorothy C C Wai
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia; ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, 3052, Australia.
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7
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de Araujo TS, Barbosa GM, Sanches K, Azevedo JM, Dos Santos Cabral KM, Almeida MS, Almeida FCL. The 1H, 15N, and 13C resonance assignments of the N-terminal domain of the nucleocapsid protein from the Middle East respiratory syndrome coronavirus. Biomol NMR Assign 2021; 15:341-345. [PMID: 33914244 PMCID: PMC8082218 DOI: 10.1007/s12104-021-10027-6] [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] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 04/20/2021] [Indexed: 06/12/2023]
Abstract
During the past 17 years, the coronaviruses have become a global public emergency, with the first appearance in 2012 in Saudi Arabia of the Middle East respiratory syndrome. Among the structural proteins encoded in the viral genome, the nucleocapsid protein is the most abundant in infected cells. It is a multifunctional phosphoprotein involved in the capsid formation, in the modulation and regulation of the viral life cycle. The N-terminal domain of N protein specifically interacts with transcriptional regulatory sequence (TRS) and is involved in the discontinuous transcription through the melting activity of double-stranded TRS (dsTRS).
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Affiliation(s)
- Talita Stelling de Araujo
- Protein Advanced Biochemistry (PAB), Institute of Medical Biochemistry (IBqM)-National Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Rio BioNMR Network (RMNRio), Rio de Janeiro, Brazil
| | - Glauce Moreno Barbosa
- National Center of Nuclear Magnetic Resonance (CNRMN), Institute of Medical Biochemistry (IBqM)-Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Rio BioNMR Network (RMNRio), Rio de Janeiro, Brazil
| | - Karoline Sanches
- National Center of Nuclear Magnetic Resonance (CNRMN), Institute of Medical Biochemistry (IBqM)-Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Rio BioNMR Network (RMNRio), Rio de Janeiro, Brazil
| | - Jéssica M Azevedo
- Protein Advanced Biochemistry (PAB), Institute of Medical Biochemistry (IBqM)-National Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Rio BioNMR Network (RMNRio), Rio de Janeiro, Brazil
| | - Katia Maria Dos Santos Cabral
- Protein Advanced Biochemistry (PAB), Institute of Medical Biochemistry (IBqM)-National Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Rio BioNMR Network (RMNRio), Rio de Janeiro, Brazil
| | - Marcius S Almeida
- Protein Advanced Biochemistry (PAB), Institute of Medical Biochemistry (IBqM)-National Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Rio BioNMR Network (RMNRio), Rio de Janeiro, Brazil
| | - Fabio C L Almeida
- National Center of Nuclear Magnetic Resonance (CNRMN), Institute of Medical Biochemistry (IBqM)-Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
- Rio BioNMR Network (RMNRio), Rio de Janeiro, Brazil.
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8
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Almeida FCL, Sanches K, Pinheiro-Aguiar R, Almeida VS, Caruso IP. Protein Surface Interactions-Theoretical and Experimental Studies. Front Mol Biosci 2021; 8:706002. [PMID: 34307462 PMCID: PMC8298896 DOI: 10.3389/fmolb.2021.706002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 06/29/2021] [Indexed: 11/13/2022] Open
Abstract
In this review, we briefly describe a theoretical discussion of protein folding, presenting the relative contribution of the hydrophobic effect versus the stabilization of proteins via direct surface forces that sometimes may be overlooked. We present NMR-based studies showing the stability of proteins lacking a hydrophobic core which in turn present hydrophobic surface clusters, such as plant defensins. Protein dynamics measurements by NMR are the key feature to understand these dynamic surface clusters. We contextualize the measurement of protein dynamics by nuclear relaxation and the information available at protein surfaces and water cavities. We also discuss the presence of hydrophobic surface clusters in multidomain proteins and their participation in transient interactions which may regulate the function of these proteins. In the end, we discuss how surface interaction regulates the reactivity of certain protein post-translational modifications, such as S-nitrosation.
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Affiliation(s)
- Fabio C L Almeida
- Institute of Medical Biochemistry-IBqM, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Karoline Sanches
- Institute of Medical Biochemistry-IBqM, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Multiuser Center for Biomolecular Innovation (CMIB), Institute of Biosciences, Letters and Exact Sciences (IBILCE), São Paulo State University "Júlio de Mesquita Filho" (UNESP), São Paulo, Brazil
| | - Ramon Pinheiro-Aguiar
- Institute of Medical Biochemistry-IBqM, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Vitor S Almeida
- Institute of Medical Biochemistry-IBqM, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Icaro P Caruso
- Institute of Medical Biochemistry-IBqM, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Multiuser Center for Biomolecular Innovation (CMIB), Institute of Biosciences, Letters and Exact Sciences (IBILCE), São Paulo State University "Júlio de Mesquita Filho" (UNESP), São Paulo, Brazil
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9
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Caruso ÍP, Sanches K, Da Poian AT, Pinheiro AS, Almeida FCL. Dynamics of the SARS-CoV-2 nucleoprotein N-terminal domain triggers RNA duplex destabilization. Biophys J 2021; 120:2814-2827. [PMID: 34197802 PMCID: PMC8239202 DOI: 10.1016/j.bpj.2021.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 12/25/2020] [Revised: 04/25/2021] [Accepted: 06/03/2021] [Indexed: 12/23/2022] Open
Abstract
The nucleocapsid (N) protein of betacoronaviruses is responsible for nucleocapsid assembly and other essential regulatory functions. The N protein N-terminal domain (N-NTD) interacts and melts the double-stranded transcriptional regulatory sequences (dsTRSs), regulating the discontinuous subgenome transcription process. Here, we used molecular dynamics (MD) simulations to study the binding of the severe acute respiratory syndrome coronavirus 2 N-NTD to nonspecific (NS) and TRS dsRNAs. We probed dsRNAs' Watson-Crick basepairing over 25 replicas of 100 ns MD simulations, showing that only one N-NTD of dimeric N is enough to destabilize dsRNAs, triggering melting initiation. dsRNA destabilization driven by N-NTD was more efficient for dsTRSs than dsNS. N-NTD dynamics, especially a tweezer-like motion of β2-β3 and Δ2-β5 loops, seems to play a key role in Watson-Crick basepairing destabilization. Based on experimental information available in the literature, we constructed kinetics models for N-NTD-mediated dsRNA melting. Our results support a 1:1 stoichiometry (N-NTD/dsRNA), matching MD simulations and raising different possibilities for N-NTD action: 1) two N-NTD arms of dimeric N would bind to two different RNA sites, either closely or spatially spaced in the viral genome, in a cooperative manner; and 2) monomeric N-NTD would be active, opening up the possibility of a regulatory dissociation event.
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Affiliation(s)
- Ícaro P Caruso
- Multiuser Center for Biomolecular Innovation and Department of Physics, Institute of Biosciences, Letters and Exact Sciences, São Paulo State University (UNESP), São José do Rio Preto, São Paulo, Brazil; Institute of Medical Biochemistry Leopoldo de Meis and National Center for Structural Biology and Bioimaging, Rio de Janeiro, Brazil.
| | - Karoline Sanches
- Multiuser Center for Biomolecular Innovation and Department of Physics, Institute of Biosciences, Letters and Exact Sciences, São Paulo State University (UNESP), São José do Rio Preto, São Paulo, Brazil; Institute of Medical Biochemistry Leopoldo de Meis and National Center for Structural Biology and Bioimaging, Rio de Janeiro, Brazil
| | - Andrea T Da Poian
- Institute of Medical Biochemistry Leopoldo de Meis and National Center for Structural Biology and Bioimaging, Rio de Janeiro, Brazil
| | - Anderson S Pinheiro
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fabio C L Almeida
- Institute of Medical Biochemistry Leopoldo de Meis and National Center for Structural Biology and Bioimaging, Rio de Janeiro, Brazil.
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10
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Sanches K, Caruso IP, Almeida FCL, Melo FA. The dynamics of free and phosphopeptide-bound Grb2-SH2 reveals two dynamically independent subdomains and an encounter complex with fuzzy interactions. Sci Rep 2020; 10:13040. [PMID: 32747626 PMCID: PMC7398917 DOI: 10.1038/s41598-020-70034-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [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: 04/11/2020] [Accepted: 07/20/2020] [Indexed: 01/18/2023] Open
Abstract
The growth factor receptor-bound protein 2 (Grb2) is a key factor in the regulation of cell survival, proliferation, differentiation, and metabolism. In its structure, the central Src homology 2 (SH2) domain is flanked by two Src homology 3 (SH3). SH2 is the most important domain in the recognition of phosphotyrosines. Here, we present the first dynamical characterization of Grb2-SH2 domain in the free state and in the presence of phosphopeptide EpYINSQV at multiple timescales, which revealed valuable information to the understanding of phophotyrosine sensing mechanism. Grb2-SH2 presented two dynamically independent subdomains, subdomain I involved in pY recognition and subdomain II is the pY + 2 specificity pocket. Under semi-saturated concentrations of pY-pep we observed fuzzy interactions, which led to chemical exchange observed by NMR. This information was used to describe the encounter complex. The association with pY-pep is dynamic, involving fuzzy interactions and multiple conformations of pY-pep with negative and hydrophobic residues, creating an electrostatic-potential that drives the binding of pY-pep. The recognition face is wider than the binding site, with many residues beyond the central SH2 binding site participating in the association complex, which contribute to explain previously reported capability of Grb2 to recognize remote pY.
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Affiliation(s)
- Karoline Sanches
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São Jose do Rio Preto, São Paulo, Brazil
| | - Icaro P Caruso
- Institute of Medical Biochemistry - IBqM, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São Jose do Rio Preto, São Paulo, Brazil
| | - Fabio C L Almeida
- Institute of Medical Biochemistry - IBqM, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. .,National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Fernando A Melo
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São Jose do Rio Preto, São Paulo, Brazil.
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11
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Sanches K, Dias RVR, da Silva PH, Fossey MA, Caruso ÍP, de Souza FP, de Oliveira LC, de Melo FA. Grb2 dimer interacts with Coumarin through SH2 domains: A combined experimental and molecular modeling study. Heliyon 2019; 5:e02869. [PMID: 31844748 PMCID: PMC6889026 DOI: 10.1016/j.heliyon.2019.e02869] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [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: 04/10/2019] [Revised: 10/19/2019] [Accepted: 11/12/2019] [Indexed: 01/15/2023] Open
Abstract
Grb2 is an important regulator of normal vs. oncogenic cell signaling transduction. It plays a pivotal role on kinase-mediated signaling transduction by linking Receptor Tyrosine kinases to Ras/MAPK pathway which is known to bring oncogenic outcome. Coumarins are phenolic molecules found in several plants and seeds widely studied because of the antibiotic, anti-inflammatory, anticoagulant, vasodilator, and anti-tumor properties. Despite several studies about the anti-tumor properties of Coumarin in vivo and the role of Grb2 in signaling pathways related to cell proliferation, a molecular level investigation of the interaction between Grb2 and Coumarin is still missing. In this study, we performed a combined set of biophysical approaches to get insights on the interaction between Grb2 in a dimer state and Coumarin. Our results showed that Coumarin interacts with Grb2 dimer through its SH2 domain. The interaction is entropically driven, 1:1 molecular ratio and presents equilibrium constant of 105 M-1. In fact, SH2 is a well-known domain and a versatile signaling module for drug targeting which has been reported to bind compounds that block Ras activation in vivo. Despite we don't know the biological role coming from interaction between Grb2-SH2 domain and Coumarin, it is clear that this molecule could work in the same way as a SH2 domain inhibitor in order to block the link of Receptor Tyrosine kinases to Ras/MAPK pathway.
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Affiliation(s)
- Karoline Sanches
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
- Multiuser Center for Biomolecular Innovation (CMIB), Institute of Biosciences, Humanities and Exact Sciences (IBILCE), São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
| | - Raphael Vinicius Rodrigues Dias
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
| | - Paulo Henrique da Silva
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
| | - Marcelo Andrés Fossey
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
- Multiuser Center for Biomolecular Innovation (CMIB), Institute of Biosciences, Humanities and Exact Sciences (IBILCE), São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
| | - Ícaro Putinhon Caruso
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
- Multiuser Center for Biomolecular Innovation (CMIB), Institute of Biosciences, Humanities and Exact Sciences (IBILCE), São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
| | - Fátima Pereira de Souza
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
- Multiuser Center for Biomolecular Innovation (CMIB), Institute of Biosciences, Humanities and Exact Sciences (IBILCE), São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
| | - Leandro Cristante de Oliveira
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
| | - Fernando Alves de Melo
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
- Multiuser Center for Biomolecular Innovation (CMIB), Institute of Biosciences, Humanities and Exact Sciences (IBILCE), São Paulo State University “Júlio de Mesquita Filho” (UNESP), São José do Rio Preto, SP, 15054-000, Brazil
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12
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Sanches K, Caruso ÍP, Almeida FCL, Melo FA. NMR assignment of free 1H, 15N and 13C-Grb2-SH2 domain. Biomol NMR Assign 2019; 13:295-298. [PMID: 31028611 DOI: 10.1007/s12104-019-09894-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/23/2019] [Indexed: 06/09/2023]
Abstract
Growth factor receptor-bound protein 2 (Grb2) is an adaptor protein composed of three domains, an N-terminal SH3 (nSH3), SH2 and a C-terminal SH3 (cSH3) domains. This multi-domain protein has been reported to be a key factor in many signaling pathways related to controlling cell survival, differentiation, and growth. The Grb2-SH2 domain has been a focus for the study of the interaction with peptides and small molecules to act as inhibitors in uncontrolled cell growth, and consequently inhibit tumor proliferation. Here we describe the almost complete assignment of the free SH2 domain at pH 7. This work prepares the ground for further structural studies, backbone dynamics, mapping of interactions and drug screening and development. TalosN secondary structure prediction showed great similarity with the available structures in the PDB.
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Affiliation(s)
- Karoline Sanches
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil
| | - Ícaro P Caruso
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil
- Institute of Medical Biochemistry (IBqM) and National Center of Nuclear Magnetic Resonance (CNRMN), Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fábio C L Almeida
- Institute of Medical Biochemistry (IBqM) and National Center of Nuclear Magnetic Resonance (CNRMN), Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Fernando A Melo
- Multiuser Center for Biomolecular Innovation (CMIB), Department of Physics, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil.
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13
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Selig L, Belo MTCT, Teixeira EG, Cunha AJLA, Brito R, Sanches K, Luna AL, Muller M, Gamba C, Belo C, Vento F, Trajman A. The study of tuberculosis-attributed deaths as a tool for disease control planning in Rio de Janeiro, Brazil. Int J Tuberc Lung Dis 2003; 7:855-9. [PMID: 12971669] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023] Open
Abstract
SETTING Two tuberculosis (TB) reference hospitals and three general hospitals in Rio de Janeiro (RJ). OBJECTIVE To analyze TB-attributed deaths as a tool for evaluating the TB control program in RJ. DESIGN Retrospective study based on 302 medical records selected from the 1998 death database. RESULTS Of 1146 registered adult (>14 years) TB-attributed deaths in RJ, 328 occurred in five hospitals, and 302 records were analyzed. Median age was 47.5 (17-89) years; 237 (78.5%) were male. Median time elapsed from onset of symptoms until diagnosis was 60 (7-730) days; median hospitalization was 60 (0-517) days. Acid-fast bacilli sputum smears were performed in 200 (69%) of 290 cases of pulmonary disease. Among 32 (36%) smear-negative patients, culture was done in only one. The recommended regimen (RHZ) was used in 175 (58%). Among 125 re-treatment patients, 55 (44%) were on RHZ instead of RHZE. Notification to health authorities was recorded in 131 (43.4%) cases. CONCLUSION In RJ, young people die from TB. Major issues identified in the public health system were poor detection and notification and a high default rate, perpetuating the spread of TB. Treating professionals do not follow guidelines, and political commitment is needed to ensure TB control in the state and in the country.
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Affiliation(s)
- L Selig
- Department of Medicine, Gama Filho University, Rio de Janeiro, Rio de Janeiro, Brazil
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