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Paul I, Roy A, Chakrabarti D, Nandi C, Ray S. Mutations in LIFR rewire the JAK/STAT signaling pathway: A study unveiling mechanistic details of Stüve-Wiedemann syndrome. Comput Biol Med 2024; 179:108797. [PMID: 38968765 DOI: 10.1016/j.compbiomed.2024.108797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 05/14/2024] [Accepted: 06/19/2024] [Indexed: 07/07/2024]
Abstract
Stüve-Wiedemann syndrome (SWS), a rare autosomal recessive disorder, characterized by diminutive size, curvature of the elongated bones, bent fingers, episodes of heightened body temperature, respiratory distress or periods of breath-holding, and challenges with feeding, especially causes fatality in infants. SWS is an outcome of potential missense mutations in the leukemia inhibitory factor receptor gene reflected as numerous amino acid mutations at protein level. Employing in silico tools and techniques like mutational screening with Pred_MutHTP, I-Mutant2.0, PANTHER.db, PolyPhen, to classify mutations as deleterious/destabilizing, in conjunction with experimental data analysis, P136A and S279P emerged as 'effect'-causing mutations. Pre-existing knowledge suggests, SWS progression is effectuated conformationally altered and dysfunctional LIFR, unable to bind to LIF and further form the LIF/LIFR/gp130 signalling complex. To gain functional insights into the effect of the said mutations on the wild type protein, an all-atom, explicit, solvent molecular dynamics simulation was performed following docking approaches. Consequently, referring to the RMSD, RMSF, protein dynamic network analysis, energy landscape plots and domain motion analysis, it was revealed that unbound LIFR_WT was more prone to LIF binding as usual whereas the mutants exhibited considerable domain closure to inhibit LIF binding. We conducted binding affinity analysis via MM/GBSA and dissociation constant estimation after LIFR-LIF docking and found the WT_complex to be more stable and compact as a whole when compared to the flexible mutant complexes thus being associated with SWS. Our study offers a route for understanding molecular level implications upon LIFR mutations which opens an avenue for therapeutic interventions.
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Affiliation(s)
- Ishani Paul
- Amity Institute of Biotechnology, Amity University, Kolkata, India
| | - Alankar Roy
- Amity Institute of Biotechnology, Amity University, Kolkata, India
| | | | - Chandreyee Nandi
- Amity Institute of Biotechnology, Amity University, Kolkata, India
| | - Sujay Ray
- Amity Institute of Biotechnology, Amity University, Kolkata, India.
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2
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Širvinskas MJ, Saunders GJ, Mitrache M, Yudin AK. Stabilization of 3 10-Helices in Macrocycles Using Dominant Rotor Methodology. J Am Chem Soc 2024; 146:24085-24093. [PMID: 39155451 DOI: 10.1021/jacs.4c08129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
Stabilization of biologically relevant structural motifs has been a long-standing challenge. Here we show that atropisomeric dominant rotors can stabilize rare 310-helices in macrocycles. The target molecules were prepared using solid-phase peptide synthesis and subjected to extensive structural analysis. Molecular dynamics (MD) simulations enabled us to acquire solution structures for the target molecules, which offered evidence for stable 310-helix formation, ordinarily a metastable state. The 310-helices were shown to retain helicity after heating to 100 °C for 72 h. Moreover, the crude atropisomeric mixtures could be thermally enriched toward 310-helical macrocycles with selectivities of >20:1.
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Affiliation(s)
- Martynas J Širvinskas
- Davenport Research Laboratories, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada
| | - George J Saunders
- Davenport Research Laboratories, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada
| | - Monica Mitrache
- Davenport Research Laboratories, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada
| | - Andrei K Yudin
- Davenport Research Laboratories, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada
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3
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Roy A, Paul I, Paul T, Hazarika K, Dihidar A, Ray S. An in-silico receptor-pharmacophore based multistep molecular docking and simulation study to evaluate the inhibitory potentials against NS1 of DENV-2. J Biomol Struct Dyn 2024; 42:6136-6164. [PMID: 37517062 DOI: 10.1080/07391102.2023.2239925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 06/25/2023] [Indexed: 08/01/2023]
Abstract
DENV-2 strain is the most fatal and infectious of the five dengue virus serotypes. The non-structural protein NS1 encoded by its genome is the most significant protein required for viral pathogenesis and replication inside the host body. Thus, targeting the NS1 protein and designing an inhibitor to limit its stability and secretion is a propitious attempt in our fight against dengue. Four novel inhibitors are designed to target the conserved cysteine residues (C55, C313, C316, and C329) and glycosylation sites (N130 and N207) of the NS1 protein in an attempt to halt the spread of the dengue infection in the host body altogether. Numerous computer-aided drug designing techniques including molecular docking, molecular dynamics simulation, virtual screening, principal component analysis, and dynamic cross-correlation matrix were employed to determine the structural and functional activity of the NS1-inhibitor complexes. From our analysis, it was evident that the extent of structural and atomic level fluctuations of the ligand-bound protein exhibited a declining trend in contrast to unbound protein which was prominently noticeable through the RMSD, RMSF, Rg, and SASA graphs. The ADMET analysis of the four ligands revealed a promising pharmacokinetics and pharmacodynamic profile, along with good bioavailability and toxicity properties. The proposed drugs when bound to the targeted cavities resulted in stable conformations in comparison to their unbound state, implying they have good affinity promising effective drug action. Thus, they can be tested in vitro and used as potential anti-dengue drugs.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Alankar Roy
- Amity Institute of Biotechnology, Amity University, Kolkata, India
| | - Ishani Paul
- Amity Institute of Biotechnology, Amity University, Kolkata, India
| | - Tanwi Paul
- Amity Institute of Biotechnology, Amity University, Kolkata, India
| | | | - Aritrika Dihidar
- Amity Institute of Biotechnology, Amity University, Kolkata, India
| | - Sujay Ray
- Amity Institute of Biotechnology, Amity University, Kolkata, India
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4
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Bhattacharya P, Mandal A. Identification of amentoflavone as a potent SARS-CoV-2 M pro inhibitor: a combination of computational studies and in vitro biological evaluation. J Biomol Struct Dyn 2024:1-19. [PMID: 38263736 DOI: 10.1080/07391102.2024.2304676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 01/07/2024] [Indexed: 01/25/2024]
Abstract
Small-molecule inhibitors of SARS-CoV-2 Mpro that block the active site pocket of the viral main protease have been considered potential therapeutics for the development of drugs against SARS-CoV-2. Here, we report the identification of amentoflavone (a biflavonoid) through docking-based virtual screening of a library comprised of 231 compounds consisting of flavonoids and isoflavonoids. The docking results were further substantiated through extensive analysis of the data obtained from all-atom 150 ns MD simulation. End-state effective free energy calculations using MM-PBSA calculations further suggested that (Ra)-amentoflavone (C3'-C8''-atropisomer) may show a greater binding affinity towards the Mpro than (Sa)-amentoflavone. In vitro cytotoxicity assay established that amentoflavone showed a high CC50 value indicating much lower toxicity. Further, potent inhibition of the Mpro by amentoflavone was established by studying the effect on HEK293T cells treated with SARS-CoV-2 Mpro expressing plasmid.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
| | - Anirban Mandal
- Department of Microbiology, Mrinalini Datta Mahavidyapith, Kolkata, India
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5
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Li J, Tan YS, Verma CS. Dissecting the geometric and hydrophobic constraints of stapled peptides. Proteins 2024. [PMID: 38196284 DOI: 10.1002/prot.26662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 12/01/2023] [Accepted: 12/27/2023] [Indexed: 01/11/2024]
Abstract
Stapled peptides are a promising class of molecules with potential as highly specific probes of protein-protein interactions and as therapeutics. Hydrocarbon stapling affects the peptide properties through the interplay of two factors: enhancing the overall hydrophobicity and constraining the conformational flexibility. By constructing a series of virtual peptides, we study the role of each factor in modulating the structural properties of a hydrocarbon-stapled peptide PM2, which has been shown to enter cells, engage its target Mouse Double Minute 2 (MDM2), and activate p53. Hamiltonian replica exchange molecular dynamics (HREMD) simulations suggest that hydrocarbon stapling favors helical populations of PM2 through a combination of the geometric constraints and the enhanced hydrophobicity of the peptide. To further understand the conformational landscape of the stapled peptides along the binding pathway, we performed HREMD simulations by restraining the peptide at different distances from MDM2. When the peptide approaches MDM2, the binding pocket undergoes dehydration which appears to be greater in the presence of the stapled peptide compared with the linear peptide. In the binding pocket, the helicity of the stapled peptide is increased due to the favorable interactions between the peptide residues as well as the staple and the microenvironment of the binding pocket, contributing to enhanced affinity. The dissection of the multifaceted mechanism of hydrocarbon stapling into individual factors not only deepens fundamental understanding of peptide stapling, but also provides guidelines for the design of new stapled peptides.
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Affiliation(s)
- Jianguo Li
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Singapore Eye Research Institute, Singapore, Singapore
| | - Yaw Sing Tan
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Chandra S Verma
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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6
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García-Morales A, Balleza D. Non-canonical helical transitions and conformational switching are associated with characteristic flexibility and disorder indices in TRP and Kv channels. Channels (Austin) 2023; 17:2212349. [PMID: 37196183 DOI: 10.1080/19336950.2023.2212349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 04/21/2023] [Accepted: 05/02/2023] [Indexed: 05/19/2023] Open
Abstract
Structural evidence and much experimental data have demonstrated the presence of non-canonical helical substructures (π and 310) in regions of great functional relevance both in TRP as in Kv channels. Through an exhaustive compositional analysis of the sequences underlying these substructures, we find that each of them is associated with characteristic local flexibility profiles, which in turn are implicated in significant conformational rearrangements and interactions with specific ligands. We found that α-to-π helical transitions are associated with patterns of local rigidity whereas α-to-310 transitions are mainly leagued with high local flexibility profiles. We also study the relationship between flexibility and protein disorder in the transmembrane domain of these proteins. By contrasting these two parameters, we located regions showing a sort of structural discrepancy between these similar but not identical protein attributes. Notably, these regions are presumably implicated in important conformational rearrangements during the gating in those channels. In that sense, finding these regions where flexibility and disorder are not proportional allows us to detect regions with potential functional dynamism. From this point of view, we highlighted some conformational rearrangements that occur during ligand binding events, the compaction, and refolding of the outer pore loops in several TRP channels, as well as the well-known S4 motion in Kv channels.
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Affiliation(s)
| | - Daniel Balleza
- Unidad de Investigación y desarrollo en Alimentos, Instituto Tecnológico de Veracruz. Tecnológico Nacional de México, Veracruz, MEXICO
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7
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Biondi B, de Pascale L, Mardirossian M, Di Stasi A, Favaro M, Scocchi M, Peggion C. Structural and biological characterization of shortened derivatives of the cathelicidin PMAP-36. Sci Rep 2023; 13:15132. [PMID: 37704689 PMCID: PMC10499915 DOI: 10.1038/s41598-023-41945-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 09/04/2023] [Indexed: 09/15/2023] Open
Abstract
Cathelicidins, a family of host defence peptides in vertebrates, play an important role in the innate immune response, exhibiting antimicrobial activity against many bacteria, as well as viruses and fungi. This work describes the design and synthesis of shortened analogues of porcine cathelicidin PMAP-36, which contain structural changes to improve the pharmacokinetic properties. In particular, 20-mers based on PMAP-36 (residues 12-31) and 13-mers (residues 12-24) with modification of amino acid residues at critical positions and introduction of lipid moieties of different lengths were studied to identify the physical parameters, including hydrophobicity, charge, and helical structure, required to optimise their antibacterial activity. Extensive conformational analysis, performed by CD and NMR, revealed that the substitution of Pro25-Pro26 with Ala25-Lys26 increased the α-helix content of the 20-mer peptides, resulting in broad-spectrum antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus epidermidis strains. Interestingly, shortening to just 13 residues resulted in only a slight decrease in antibacterial activity. Furthermore, two sequences, a 13-mer and a 20-mer, did not show cytotoxicity against HaCat cells up to 64 µM, indicating that both derivatives are not only effective but also selective antimicrobial peptides. In the short peptide, the introduction of the helicogenic α-aminoisobutyric acid forced the helix toward a prevailing 310 structure, allowing the antimicrobial activity to be maintained. Preliminary tests of resistance to Ser protease chymotrypsin indicated that this modification resulted in a peptide with an increased in vivo lifespan. Thus, some of the PMAP-36 derivatives studied in this work show a good balance between chain length, antibacterial activity, and selectivity, so they represent a good starting point for the development of even more effective and proteolysis-resistant active peptides.
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Affiliation(s)
- Barbara Biondi
- Institute of Biomolecular Chemistry, CNR, Padova Unit, Padova, Italy
| | - Luigi de Pascale
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | | | - Adriana Di Stasi
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Matteo Favaro
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Marco Scocchi
- Department of Life Sciences, University of Trieste, Trieste, Italy.
| | - Cristina Peggion
- Institute of Biomolecular Chemistry, CNR, Padova Unit, Padova, Italy.
- Department of Chemical Sciences, University of Padova, Padova, Italy.
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8
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Mam B, Tsitsanou KE, Liggri PGV, Saitta F, Stamati ECV, Mahita J, Leonis G, Drakou CE, Papadopoulos M, Arnaud P, Offmann B, Fessas D, Sowdhamini R, Zographos SE. Influence of pH on indole-dependent heterodimeric interactions between Anopheles gambiae odorant-binding proteins OBP1 and OBP4. Int J Biol Macromol 2023:125422. [PMID: 37330089 DOI: 10.1016/j.ijbiomac.2023.125422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/30/2023] [Accepted: 06/14/2023] [Indexed: 06/19/2023]
Abstract
Insect Odorant Binding Proteins (OBPs) constitute important components of their olfactory apparatus, as they are essential for odor recognition. OBPs undergo conformational changes upon pH change, altering their interactions with odorants. Moreover, they can form heterodimers with novel binding characteristics. Anopheles gambiae OBP1 and OBP4 were found capable of forming heterodimers possibly involved in the specific perception of the attractant indole. In order to understand how these OBPs interact in the presence of indole and to investigate the likelihood of a pH-dependent heterodimerization mechanism, the crystal structures of OBP4 at pH 4.6 and 8.5 were determined. Structural comparison to each other and with the OBP4-indole complex (3Q8I, pH 6.85) revealed a flexible N-terminus and conformational changes in the α4-loop-α5 region at acidic pH. Fluorescence competition assays showed a weak binding of indole to OBP4 that become further impaired at acidic pH. Additional Molecular Dynamic and Differential Scanning Calorimetry studies displayed that the influence of pH on OBP4 stability is significant compared to the modest effect of indole. Furthermore, OBP1-OBP4 heterodimeric models were generated at pH 4.5, 6.5, and 8.5, and compared concerning their interface energy and cross-correlated motions in the absence and presence of indole. The results indicate that the increase in pH may induce the stabilization of OBP4 by increasing its helicity, thereby enabling indole binding at neutral pH that further stabilizes the protein and possibly promotes the creation of a binding site for OBP1. A decrease in interface stability and loss of correlated motions upon transition to acidic pH may provoke the heterodimeric dissociation allowing indole release. Finally, we propose a potential OBP1-OBP4 heterodimer formation/disruption mechanism induced by pH change and indole binding.
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Affiliation(s)
- Bhavika Mam
- National Centre for Biological Sciences, Bangalore, Karnataka, India; The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, Karnataka, India
| | - Katerina E Tsitsanou
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece
| | - Panagiota G V Liggri
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece; Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
| | - Francesca Saitta
- Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy
| | - Evgenia C V Stamati
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece; Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
| | - Jarjapu Mahita
- National Centre for Biological Sciences, Bangalore, Karnataka, India
| | - George Leonis
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece
| | - Christina E Drakou
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece
| | - Manthos Papadopoulos
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece
| | - Philippe Arnaud
- Protein Engineering and Functionality Unit, UMR CNRS 6286, University of Nantes, Nantes, France
| | - Bernard Offmann
- Protein Engineering and Functionality Unit, UMR CNRS 6286, University of Nantes, Nantes, France
| | - Dimitrios Fessas
- Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy
| | | | - Spyros E Zographos
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece.
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9
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Ausili A. Despite their structural similarities, the cytosolic isoforms of human Hsp90 show different behaviour in thermal unfolding due to their conformation: An FTIR study. Arch Biochem Biophys 2023; 740:109599. [PMID: 37028636 DOI: 10.1016/j.abb.2023.109599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/16/2023] [Accepted: 04/05/2023] [Indexed: 04/09/2023]
Abstract
Heat shock proteins 90 (Hsp90) are chaperones that promote the proper folding of other proteins under high temperature stress situations. Hsp90s are highly conserved and ubiquitous proteins, and in mammalian cells, they are localized in the cytoplasm, endoplasmic reticulum, and mitochondria. Cytoplasmic Hsp90 are named Hsp90α and Hsp90β and differ mainly in their expression pattern: Hsp90α is expressed under stress conditions, while Hsp90β is a constitutive protein. Structurally, both share the same characteristics by presenting three well-conserved domains, one of which, the N-terminal domain, has a binding site for ATP to which various drugs targeting this protein, including radicicol, can bind. The protein is mainly found in dimeric form and adopts different conformations depending on the presence of ligands, co-chaperones and client proteins. In this study, some aspects of structure and thermal unfolding of cytoplasmic human Hsp90 were analysed by infrared spectroscopy. The effect on Hsp90β of binding with a non-hydrolysable ATP analogue and radicicol was also examined. The results obtained showed that despite the high similarity in secondary structure the two isoforms exhibit substantial differences in their behaviour during thermal unfolding, as Hsp90α exhibits higher thermal stability, slower denaturation process and different event sequence during unfolding. Ligand binding strongly stabilizes Hsp90β and slightly modifies the secondary structure of the protein as well. Most likely, these structural and thermostability characteristics are closely related to the conformational cycling of the chaperone and its propensity to exist in monomer or dimer form.
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Affiliation(s)
- Alessio Ausili
- Institute of Plant Biochemistry and Photosynthesis (IBVF), Consejo Superior de Investigaciones Científicas, 41092, Seville, Spain.
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10
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Newing TP, Brewster JL, Fitschen LJ, Bouwer JC, Johnston NP, Yu H, Tolun G. Redβ 177 annealase structure reveals details of oligomerization and λ Red-mediated homologous DNA recombination. Nat Commun 2022; 13:5649. [PMID: 36163171 PMCID: PMC9512822 DOI: 10.1038/s41467-022-33090-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/31/2022] [Indexed: 11/21/2022] Open
Abstract
The Redβ protein of the bacteriophage λ red recombination system is a model annealase which catalyzes single-strand annealing homologous DNA recombination. Here we present the structure of a helical oligomeric annealing intermediate of Redβ, consisting of N-terminal residues 1-177 bound to two complementary 27mer oligonucleotides, determined via cryogenic electron microscopy (cryo-EM) to a final resolution of 3.3 Å. The structure reveals a continuous binding groove which positions and stabilizes complementary DNA strands in a planar orientation to facilitate base pairing via a network of hydrogen bonding. Definition of the inter-subunit interface provides a structural basis for the propensity of Redβ to oligomerize into functionally significant long helical filaments, a trait shared by most annealases. Our cryo-EM structure and molecular dynamics simulations suggest that residues 133-138 form a flexible loop which modulates access to the binding groove. More than half a century after its discovery, this combination of structural and computational observations has allowed us to propose molecular mechanisms for the actions of the model annealase Redβ, a defining member of the Redβ/RecT protein family. Redβ annealase catalyses single-strand annealing homologous DNA recombination. Here, the authors present a cryo-EM structure of a Redβ annealing intermediate bound to two complementary 27mer oligonucleotides.
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Affiliation(s)
- Timothy P Newing
- School of Chemistry and Molecular Bioscience, and Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Jodi L Brewster
- School of Chemistry and Molecular Bioscience, and Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, University of Wollongong, Wollongong, NSW, Australia
| | - Lucy J Fitschen
- School of Chemistry and Molecular Bioscience, and Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, University of Wollongong, Wollongong, NSW, Australia
| | - James C Bouwer
- School of Chemistry and Molecular Bioscience, and Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, University of Wollongong, Wollongong, NSW, Australia
| | - Nikolas P Johnston
- School of Chemistry and Molecular Bioscience, and Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia
| | - Haibo Yu
- School of Chemistry and Molecular Bioscience, and Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Gökhan Tolun
- School of Chemistry and Molecular Bioscience, and Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia. .,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia. .,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, University of Wollongong, Wollongong, NSW, Australia.
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11
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The neuropeptide galanin adopts an irregular secondary structure. Biochem Biophys Res Commun 2022; 626:121-128. [PMID: 35994823 DOI: 10.1016/j.bbrc.2022.08.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 08/11/2022] [Indexed: 11/22/2022]
Abstract
Human galanin is a 30-residue neuropeptide targeted for development of analgesics, antidepressants, and anticonvulsants. While previous work from our group and others has already produced significant insights into galanin's N-terminal region, no extant structures of galanin in databases include its full-length sequence and the function of its C-terminus remains ambiguous. We report the NMR solution structure of full-length human galanin C-terminal amide, determined from 2D 1H-1H COSY, TOCSY, and ROESY NMR data. Galanin adopts an irregular helical structure across its N-terminus, likely the average of several coiling states. We present the NMR structure of a peptide encompassing the C-terminus of galanin as a stand-alone fragment. The C-terminus of full-length galanin appears to indirectly assist the intramolecular association of hydrophobic sidechains within its N-terminus, remotely rigidifying their position when compared to previously studied N-terminal galanin fragments. By contrast, there is flexibility in the C-terminus of galanin, characterized by two i to i + 2 hydrogen-bonded turns within an otherwise dynamic backbone. The C-terminal portion of the peptide renders it soluble, and plays a hitherto undescribed biophysical role in pre-organizing the galanin receptor binding epitope. We speculate that hydrophilic microdomains of signaling peptides, hormones, and perhaps intrinsically disordered proteins may also function similarly.
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Abstract
Linus Pauling in 1950 published a three-dimensional model for a universal protein secondary structure motif which he initially called the alpha-spiral. Jack Dunitz, then a postdoc in Pauling's lab suggested to Pauling that the term helix is more accurate than spiral when describing the right-handed peptide and protein coiled structures. Pauling agreed, hence the rise of the alpha-helix, and, by extension, the ‘double helix’ structure of DNA. Although structural biologists and protein chemists are familiar with varying polar and apolar characters of amino acids in alpha-helices, to non-experts the three chemically distinct alpha-helix types classified here may hide in plain sight.
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Affiliation(s)
- Shuguang Zhang
- Laboratory of Molecular Architecture, Media Lab, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - Martin Egli
- Department of Biochemistry, Vanderbilt University, School of Medicine, Nashville, Tennessee 37232-0146, USA
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13
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Ghosh S, Tran PN, McElheny D, Perez JJ, Nguyen AI. Peptidic Scaffolds Enable Rapid and Multivariate Secondary Sphere Evolution for an Abiotic Metallocatalyst. Inorg Chem 2022; 61:6679-6687. [PMID: 35446044 DOI: 10.1021/acs.inorgchem.2c00901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metalloenzymes have benefited from the iterative process of evolution to achieve the precise arrangements of secondary sphere non-covalent interactions that enhance metal-centered catalysis. Iterative synthesis of scaffolds that display complex secondary sphere elements in abiotic systems can be highly challenging and time-intensive. To overcome this synthetic bottleneck, we developed a highly modular and rapid synthetic strategy, leveraging the efficiency of solid-phase peptide synthesis and conformational control afforded by non-canonical residues to construct a ligand platform displaying up to four unique residues of varying electronics and sterics in the secondary coordination sphere. As a proof-of-concept that peptidic secondary sphere can cooperate with the metal complex, we applied this scaffold to a well-known, modestly active C-H oxidizing Fe catalyst to evolve specific non-covalent interactions that is more than double its catalytic activity. Solution-state NMR structures of several catalyst variants suggest that higher activity is correlated with a hydrophobic pocket above the Fe center that may enhance the formation of a catalyst-substrate complex. Above all, we show that peptides are a convenient, highly modular, and structurally defined ligand platform for creating secondary coordination spheres that comprise multiple, diverse functional groups.
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Affiliation(s)
- Sabari Ghosh
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Phuong Nguyen Tran
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Dan McElheny
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Juan J Perez
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Andy I Nguyen
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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14
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Craveur P, Narwani TJ, Srinivasan N, Gelly JC, Rebehmed J, de Brevern AG. Shaking the β-Bulges. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2022; 19:14-18. [PMID: 34115590 DOI: 10.1109/tcbb.2021.3088444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
β-bulges are irregularities inside the β-sheets. They represent more than 3 percent of the protein residues, i.e., they are as frequent as 3.10 helices. In terms of evolution, β-bulges are not more conserved than any other local protein conformations within homologous protein structures. In a first of its kind study, we have investigated the dynamical behaviour of β-bulges using the largest known set of protein molecular dynamics simulations. We observed that more than 50 percent of the existing β-bulges in protein crystal structures remained stable during dynamics while more than1/6th were not stable at all and disappeared entirely. Surprisingly, 1.1 percent of β-bulges that appeared remained stable. β-bulges have been categorized in different subtypes. The most common β-bulges' types are the smallest insertion in β-strands (namely AC and AG); they are found as stable as the whole β-bulges dataset. Low occurring types (namely PC and AS), that have the largest insertions, are significantly more stable than expected. Thus, this pioneer study allowed to precisely quantify the stability of the β-bulges, demonstrating their structural robustness, with few unexpected cases raising structural questions.
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15
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Masamba P, Weber BW, Sewell BT, Kappo AP. Crystallization and preliminary structural determination of the universal stress G4LZI3 protein from Schistosoma mansoni. INFORMATICS IN MEDICINE UNLOCKED 2022. [DOI: 10.1016/j.imu.2022.101057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022] Open
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16
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Rose J, Brand I, Bilstein-Schloemer M, Jachimska B, Twyman RM, Prüfer D, Noll GA. The Ca 2+ response of a smart forisome protein is dependent on polymerization. Protein Sci 2021; 31:602-612. [PMID: 34897845 PMCID: PMC8862433 DOI: 10.1002/pro.4256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/19/2021] [Accepted: 12/08/2021] [Indexed: 01/28/2023]
Abstract
Forisomes are giant self-assembling mechanoproteins that undergo reversible structural changes in response to Ca2+ and various other stimuli. Artificial forisomes assembled from the monomer MtSEO-F1 can be used as smart biomaterials, but the molecular basis of their functionality is not understood. To determine the role of protein polymerization in forisome activity, we tested the Ca2+ association of MtSEO-F1 dimers (the basic polymerization unit) by circular dichroism spectroscopy and microscale thermophoresis. We found that soluble MtSEO-F1 dimers neither associate with Ca2+ nor undergo structural changes. However, polarization modulation infrared reflection absorption spectroscopy revealed that aggregated MtSEO-F1 dimers and fully-assembled forisomes associate with Ca2+ , allowing the hydration of poorly-hydrated protein areas. A change in the signal profile of complete forisomes indicated that Ca2+ interacts with negatively-charged regions in the protein complexes that only become available during aggregation. We conclude that aggregation is required to establish the Ca2+ response of forisome polymers.
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Affiliation(s)
- Judith Rose
- Institute for Plant Biology and Biotechnology, University of Münster, Münster, Germany
| | - Izabella Brand
- Department of Chemistry, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | | | - Barbara Jachimska
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Krakow, Poland
| | | | - Dirk Prüfer
- Institute for Plant Biology and Biotechnology, University of Münster, Münster, Germany.,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Münster, Germany
| | - Gundula A Noll
- Institute for Plant Biology and Biotechnology, University of Münster, Münster, Germany.,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Münster, Germany
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17
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Sidorova A, Bystrov V, Lutsenko A, Shpigun D, Belova E, Likhachev I. Quantitative Assessment of Chirality of Protein Secondary Structures and Phenylalanine Peptide Nanotubes. NANOMATERIALS 2021; 11:nano11123299. [PMID: 34947648 PMCID: PMC8707344 DOI: 10.3390/nano11123299] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 11/26/2021] [Accepted: 12/02/2021] [Indexed: 01/25/2023]
Abstract
In this study we consider the features of spatial-structure formation in proteins and their application in bioengineering. Methods for the quantitative assessment of the chirality of regular helical and irregular structures of proteins are presented. The features of self-assembly of phenylalanine (F) into peptide nanotubes (PNT), which form helices of different chirality, are also analyzed. A method is proposed for calculating the magnitude and sign of the chirality of helix-like peptide nanotubes using a sequence of vectors for the dipole moments of individual peptides.
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Affiliation(s)
- Alla Sidorova
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia; (A.L.); (D.S.); (E.B.)
- Correspondence:
| | - Vladimir Bystrov
- Institute of Mathematical Problems of Biology, The Branch of Keldysh Institute of Applied Mathematics, RAS, 142290 Pushchino, Russia; (V.B.); (I.L.)
| | - Aleksey Lutsenko
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia; (A.L.); (D.S.); (E.B.)
| | - Denis Shpigun
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia; (A.L.); (D.S.); (E.B.)
| | - Ekaterina Belova
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia; (A.L.); (D.S.); (E.B.)
| | - Ilya Likhachev
- Institute of Mathematical Problems of Biology, The Branch of Keldysh Institute of Applied Mathematics, RAS, 142290 Pushchino, Russia; (V.B.); (I.L.)
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18
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Komorek P, Jachimska B, Brand I. Adsorption of lysozyme on gold surfaces in the presence of an external electric potential. Bioelectrochemistry 2021; 142:107946. [PMID: 34507162 DOI: 10.1016/j.bioelechem.2021.107946] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/30/2021] [Accepted: 08/29/2021] [Indexed: 10/20/2022]
Abstract
Adsorbed protein films consist of essential building blocks of many biotechnological and biomedical devices. The electrostatic potential may significantly modulate the protein behaviour on surfaces, affecting their structure and biological activity. In this study, lysozyme was used to investigate the effects of applied electric potentials on adsorption and the protein structure. The pH and the surface charge determine the amount and secondary structure of adsorbed lysozyme on a gold surface. In-situ measurements using polarization modulation infrared reflection absorption spectroscopy indicated that the concentration of both the adsorbed anions and the lysozyme led to conformational changes in the protein film, which was demonstrated by a greater amount of aggregated β-sheets in films fabricated at net positive charges of the Au electrode (Eads > Epzc). The changes in secondary structure involved two parallel processes. One comprised changes in the hydration/hydrogen-bond network at helices, leading to diverse helical structures: α-, 310- and/or π-helices. In the second process β-turns, β-sheets, and random coils displayed an ability to form aggregated β-sheet structures. The study illuminates the understanding of electrical potential-dependent changes involved in the protein misfolding process.
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Affiliation(s)
- Paulina Komorek
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Niezapominajek 8, 30-239 Cracow, Poland
| | - Barbara Jachimska
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Niezapominajek 8, 30-239 Cracow, Poland.
| | - Izabella Brand
- Department of Chemistry, University of Oldenburg, 26111 Oldenburg, Germany.
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19
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Zhuang Y, Bureau HR, Lopez C, Bucher R, Quirk S, Hernandez R. Energetics and structure of alanine-rich α-helices via adaptive steered molecular dynamics. Biophys J 2021; 120:2009-2018. [PMID: 33775636 PMCID: PMC8204395 DOI: 10.1016/j.bpj.2021.03.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 03/03/2021] [Accepted: 03/18/2021] [Indexed: 12/12/2022] Open
Abstract
The energetics and hydrogen bonding profiles of the helix-to-coil transition were found to be an additive property and to increase linearly with chain length, respectively, in alanine-rich α-helical peptides. A model system of polyalanine repeats was used to establish this hypothesis for the energetic trends and hydrogen bonding profiles. Numerical measurements of a synthesized polypeptide Ac-Y(AEAAKA)kF-NH2 and a natural α-helical peptide a2N (1-17) provide evidence of the hypothesis's generality. Adaptive steered molecular dynamics was employed to investigate the mechanical unfolding of all of these alanine-rich polypeptides. We found that the helix-to-coil transition is primarily dependent on the breaking of the intramolecular backbone hydrogen bonds and independent of specific side-chain interactions and chain length. The mechanical unfolding of the α-helical peptides results in a turnover mechanism in which a 310-helical structure forms during the unfolding, remaining at a near constant population and thereby maintaining additivity in the free energy. The intermediate partially unfolded structures exhibited polyproline II helical structure as previously seen by others. In summary, we found that the average force required to pull alanine-rich α-helical peptides in between the endpoints-namely the native structure and free coil-is nearly independent of the length or the specific primary structure.
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Affiliation(s)
- Yi Zhuang
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland
| | - Hailey R Bureau
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland
| | - Christine Lopez
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland
| | - Ryan Bucher
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland
| | | | - Rigoberto Hernandez
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland; Departments of Chemical and Biomolecular Engineering, and Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland.
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20
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Role of intramolecular hydrogen bonds in promoting electron flow through amino acid and oligopeptide conjugates. Proc Natl Acad Sci U S A 2021; 118:2026462118. [PMID: 33707214 DOI: 10.1073/pnas.2026462118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Elucidating the factors that control charge transfer rates in relatively flexible conjugates is of importance for understanding energy flows in biology as well as assisting the design and construction of electronic devices. Here, we report ultrafast electron transfer (ET) and hole transfer (HT) between a corrole (Cor) donor linked to a perylene-diimide (PDI) acceptor by a tetrameric alanine (Ala)4 Selective photoexcitation of the donor and acceptor triggers subpicosecond and picosecond ET and HT. Replacement of the (Ala)4 linker with either a single alanine or phenylalanine does not substantially affect the ET and HT kinetics. We infer that electronic coupling in these reactions is not mediated by tetrapeptide backbone nor by direct donor-acceptor interactions. Employing a combination of NMR, circular dichroism, and computational studies, we show that intramolecular hydrogen bonding brings the donor and the acceptor into proximity in a "scorpion-shaped" molecular architecture, thereby accounting for the unusually high ET and HT rates. Photoinduced charge transfer relies on a (Cor)NH…O=C-NH…O=C(PDI) electronic-coupling pathway involving two pivotal hydrogen bonds and a central amide group as a mediator. Our work provides guidelines for construction of effective donor-acceptor assemblies linked by long flexible bridges as well as insights into structural motifs for mediating ET and HT in proteins.
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21
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Samuel PP, Case DA. Atomistic Simulations of Heme Dissociation Pathways in Human Methemoglobins Reveal Hidden Intermediates. Biochemistry 2020; 59:4093-4107. [PMID: 32945658 DOI: 10.1021/acs.biochem.0c00607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Heme dissociations disrupt function and structural integrity of human hemoglobin and trigger various cardiovascular complications. These events become significant in methemoglobins that have undergone autoxidation of ferrous into ferric heme. We have structurally characterized the heme disassociation pathways for adult tetrameric methemoglobins using all-atom molecular dynamics simulations. These reveal that bis-histidine hemichromes, characterized here by the coordination of heme iron to both the F8 (proximal) and E7 (distal) histidines, are seen as intermediates following dissociation of the water molecule distally bound to each heme iron. Later, the breaking of coordination between heme iron and proximal histidine disrupts the F helix and pushes it away from the heme cavity, enabling both bulk solvent penetration and disruption of tetramer interface interactions. The interactions inhibiting heme dissociation were then seen to be (i) either a direct or a water-molecule-mediated interaction between distal histidine and heme iron and (ii) stacking between heme and the αCE1/βCD1 phenylalanine residue. These interactions are less important in the β than in α subunits due to a more flexible β subunit CE loop region. The absence of a distal histidine interaction in the H(E7)L mutant and increased heme cavity volume in the V(E11)A mutant both promoted heme escape from the protein interior. Adult and fetal hemoglobins were seen to share a general heme disassociation pathway and intermediates due to the conservation of key heme pocket residues. The intermediates seen here are analyzed in light of experimental studies of heme dissociation and pathways of certain hemoglobinopathies.
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Affiliation(s)
- Premila P Samuel
- Institute for Quantitative Biomedicine, Rutgers University, Piscataway, New Jersey 08854, United States
| | - David A Case
- Institute for Quantitative Biomedicine, Rutgers University, Piscataway, New Jersey 08854, United States.,Department of Chemistry & Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, United States
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22
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Hiew SH, Mohanram H, Ning L, Guo J, Sánchez‐Ferrer A, Shi X, Pervushin K, Mu Y, Mezzenga R, Miserez A. A Short Peptide Hydrogel with High Stiffness Induced by 3 10-Helices to β-Sheet Transition in Water. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1901173. [PMID: 31728282 PMCID: PMC6839752 DOI: 10.1002/advs.201901173] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/23/2019] [Indexed: 05/24/2023]
Abstract
Biological gels generally require polymeric chains that produce long-lived physical entanglements. Low molecular weight colloids offer an alternative to macromolecular gels, but often require ad-hoc synthetic procedures. Here, a short biomimetic peptide composed of eight amino acid residues derived from squid sucker ring teeth proteins is demonstrated to form hydrogel in water without any cross-linking agent or chemical modification and exhibits a stiffness on par with the stiffest peptide hydrogels. Combining solution and solid-state NMR, circular dichroism, infrared spectroscopy, and X-ray scattering, the peptide is shown to form a supramolecular, semiflexible gel assembled from unusual right-handed 310-helices stabilized in solution by π-π stacking. During gelation, the 310-helices undergo conformational transition into antiparallel β-sheets with formation of new interpeptide hydrophobic interactions, and molecular dynamic simulations corroborate stabilization by cross β-sheet oligomerization. The current study broadens the range of secondary structures available to create supramolecular hydrogels, and introduces 310-helices as transient building blocks for gelation via a 310-to-β-sheet conformational transition.
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Affiliation(s)
- Shu Hui Hiew
- Center for Biomimetic Sensor ScienceSchool of Materials Science and EngineeringNanyang Technological UniversitySingapore639798Singapore
| | - Harini Mohanram
- Center for Biomimetic Sensor ScienceSchool of Materials Science and EngineeringNanyang Technological UniversitySingapore639798Singapore
| | - Lulu Ning
- School of Biological SciencesNanyang Technological UniversitySingapore637551Singapore
| | - Jingjing Guo
- School of Biological SciencesNanyang Technological UniversitySingapore637551Singapore
| | | | - Xiangyan Shi
- School of Biological SciencesNanyang Technological UniversitySingapore637551Singapore
| | - Konstantin Pervushin
- School of Biological SciencesNanyang Technological UniversitySingapore637551Singapore
| | - Yuguang Mu
- School of Biological SciencesNanyang Technological UniversitySingapore637551Singapore
| | - Raffaele Mezzenga
- Department of Health Sciences & TechnologyETH ZurichZurichCH‐8092Switzerland
| | - Ali Miserez
- Center for Biomimetic Sensor ScienceSchool of Materials Science and EngineeringNanyang Technological UniversitySingapore639798Singapore
- School of Biological SciencesNanyang Technological UniversitySingapore637551Singapore
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23
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Polyproline chains destabilize the Alzheimer's amyloid-β protofibrils: A molecular dynamics simulation study. J Mol Graph Model 2019; 93:107456. [PMID: 31581064 DOI: 10.1016/j.jmgm.2019.107456] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/22/2019] [Accepted: 09/24/2019] [Indexed: 12/11/2022]
Abstract
Alzheimer's is a fatal neurodegenerative disease for which there is no cure at present. The disease is characterized by the presence of plaques, principally comprising the amyloid-β peptide (viz., β-sheet) in the brains of a patient. In our present work, we study the interaction of these β-sheets with a different number of repeating units of proline (β-sheet breaker) by docking and all atom molecular dynamics simulations. Our results indicate that proline can break the amyloid protofibrils apart, cause them to break their β-sheet structure, and in some cases even induce the formation of 310 helices, which may be intermediates in the unfolding of these β-sheets. We have also observed that some of the important hydrogen bonds and salt bridges between chains were disrupted by proline and the tight interatomic packing of atoms in the fibrils was made relatively loose. Proline chains had a tendency to make several contacts with charged residues. Proline chains binded well to the fibrils by strong electrostatic interactions while hydrophobic interactions played a less important role. This leads to the conclusion that proline can break the amyloid fibrils apart and can be considered in the design of novel peptide-based drugs to treat Alzheimer's disease and potentially other diseases caused by the misfolding of proteins into β-sheets.
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24
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Mehra R, Kepp KP. Cell size effects in the molecular dynamics of the intrinsically disordered Aβ peptide. J Chem Phys 2019; 151:085101. [DOI: 10.1063/1.5115085] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- Rukmankesh Mehra
- Technical University of Denmark, DTU Chemistry, Building 206, 2800 Kgs. Lyngby, Denmark
| | - Kasper P. Kepp
- Technical University of Denmark, DTU Chemistry, Building 206, 2800 Kgs. Lyngby, Denmark
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25
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Sun Z, Wang X. Thermodynamics of Helix formation in small peptides of varying lengthin vacuo, implicit solvent and explicit solvent: Comparison between AMBER force fields. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2019. [DOI: 10.1142/s0219633619500159] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Helix formation is of great significance in protein folding. The helix-forming tendencies of amino acids are accumulated along the sequence to determine the helix-forming tendency of peptides. Computer simulation can be used to model this process in atomic details and give structural insights. In the current work, we employ equilibrate-state free energy simulation to systematically study the folding/unfolding thermodynamics of a series of mutated peptides. Two AMBER force fields including AMBER99SB and AMBER14SB are compared. The new 14SB force field uses refitted torsion parameters compared with 99SB and they share the same atomic charge scheme. We find that in vacuo the helix formation is mutation dependent, which reflects the different helix propensities of different amino acids. In general, there are helix formers, helix indifferent groups and helix breakers. The helical structure becomes more favored when the length of the sequence becomes longer, which arises from the formation of additional backbone hydrogen bonds in the lengthened sequence. Therefore, the helix indifferent groups and helix breakers will become helix formers in long sequences. Also, protonation-dependent helix formation is observed for ionizable groups. In 14SB, the helical structures are more stable than in 99SB and differences can be observed in their grouping schemes, especially in the helix indifferent group. In solvents, all mutations are helix indifferent due to protein–solvent interactions. The decrease in the number of backbone hydrogen bonds is the same with the increase in the number of protein–water hydrogen bonds. The 14SB in explicit solvent is able to capture the free energy minima in the helical state while 14SB in implicit solvent, 99SB in explicit solvent and 99SB in implicit solvent cannot. The helix propensities calculated under 14SB agree with the corresponding experimental values, while the 99SB results obviously deviate from the references. Hence, implicit solvent models are unable to correctly describe the thermodynamics even for the simple helix formation in isolated peptides. Well-developed force fields and explicit solvents are needed to correctly describe the protein dynamics. Aside from the free energy, differences in conformational ensemble under different force fields in different solvent models are observed. The numbers of hydrogen bonds formed under different force fields agree and they are mostly determined by the solvent model.
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Affiliation(s)
- Zhaoxi Sun
- State Key Laboratory of Precision Spectroscopy, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, P. R. China
- Computational Biomedicine (IAS-5/INM-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - Xiaohui Wang
- State Key Laboratory of Precision Spectroscopy, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, P. R. China
- Institute of Computational Science, Universitàdella Svizzeraitaliana (USI), Via Giuseppe Buffi 13, CH-6900 Lugano, Ticino, Switzerland
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26
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Banerjee A, Ray S. Molecular interactions and mutational impact upon rhodopsin (G90→D90) for hindering dark adaptation of eye: A comparative structural level outlook for signaling mechanism in night blindness. Mutat Res 2019; 814:7-14. [PMID: 30659944 DOI: 10.1016/j.mrfmmm.2019.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 10/17/2018] [Accepted: 01/03/2019] [Indexed: 06/09/2023]
Abstract
For night blindness, a detailed structural exploration of the interactions among G-protein receptor rhodopsin, transducin and arrestin was performed. Rhodopsin is responsible for dim light vision while a point mutation (G90→D90) results in an adverse change in its photo-transduction. The validated 3D models of the three proteins were utilized, and upon mutation and interactions, rhodopsin attained higher stability (evaluated through thermodynamic energy calculations, electrostatic surface potential and solvent accessible area), thereby participating strongly with transducin. Conformational switches in mutated rhodopsin also depicted a firm conformation with few 310 helices accompanied by increased percentage of pure α-helices and sheets. All evaluations were corroborated through paired T-tests. Glu33 (glycosylated unit in the N-terminal zone) of rhodopsin plays a chief role in the overall interaction pattern. Arg69 and Glu33 from wild-type rhodopsin participated in ionic interactions, while the latter set of ionic interaction remained preserved even after mutation. Cys323 (C-terminal residue) and Arg69 formed H-bonds from the wild-type rhodopsin. Cys323 exceptionally supports cellular signaling pattern in the non-mutated situation and for the non-sufferers of night-blindness. Ser297 and Tyr43 from mutated rhodopsin reside in helices and interact with Thr32 of transducin, preserving the steady conformation in activated interacted state, even in the dark. Ser297 lies adjoined to Lys296 (retinal attachment site), which resides in NPXXY motif (an "activation switch" for signal transduction). Thus, the molecular facet for involvement of photo-transduction, which holds a paramount zone in ophthalmology, was dealt with. This might instigate the future prospect for drug discovery to prevent such mutations.
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Affiliation(s)
- Arundhati Banerjee
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, Nadia, India.
| | - Sujay Ray
- Amity Institute of Biotechnology, Amity University, Kolkata, India.
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27
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Abstract
Melittin is an extensively studied, 26-residue toxic peptide from honey bee venom. Because of its versatility in adopting a variety of secondary (helix or coil) and quaternary (monomer or tetramer) structures in various environments, melittin has been the focus of numerous investigations as a model peptide in protein folding studies as well as in studies involving binding to proteins, lipids, and polysaccharides. A significant body of evidence supports the view that melittin binds to these macromolecules in a predominantly helical conformation, but detailed structural knowledge of this conformation is lacking. In this report, we present nuclear magnetic resonance (NMR)-based structural insights into the helix formation of recombinant melittin in the presence of trifluoroethanol (TFE): a known secondary structure inducer in peptides. These studies were performed at neutral pH, with micromolar amounts of the peptide. Using nuclear Overhauser effect (NOE)-derived distance restraints from three-dimensional NMR spectra, we determined the atomic resolution solution NMR structure of recombinant melittin bearing a TFE-stabilized helix. To circumvent the complications with structure determination of small peptides with high conformational flexibility, we developed a workflow for enhancing proton NOEs by increasing the viscosity of the medium. In the TFE-containing medium, recombinant monomeric melittin forms a long, continuous helical structure, which consists of the N- and C-terminal α-helices and the noncanonical 310-helix in the middle. The noncanonical 310-helix is missing in the previously solved X-ray structure of tetrameric melittin and the NMR structure of melittin in methanol. Melittin's structure in TFE-containing medium provides insights into melittin's conformational transitions, which are relevant to the peptide's interactions with its biological targets.
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Affiliation(s)
- Lisa S Ramirez
- Department of Chemistry , State University of New York at Albany , Albany , New York 12222 , United States
| | - Jayanti Pande
- Department of Chemistry , State University of New York at Albany , Albany , New York 12222 , United States
| | - Alexander Shekhtman
- Department of Chemistry , State University of New York at Albany , Albany , New York 12222 , United States
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28
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Thermodynamics of helix formation in small peptides of varying length in vacuo, in implicit solvent, and in explicit solvent. J Mol Model 2018; 25:3. [DOI: 10.1007/s00894-018-3886-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 11/28/2018] [Indexed: 10/27/2022]
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29
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He C, Custer G, Wang J, Matysiak S, Beckett D. Superrepression through Altered Corepressor–Activated Protein:Protein Interactions. Biochemistry 2018; 57:1119-1129. [DOI: 10.1021/acs.biochem.7b01122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chenlu He
- Department of Chemistry & Biochemistry and ‡Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
| | - Gregory Custer
- Department of Chemistry & Biochemistry and ‡Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
| | - Jingheng Wang
- Department of Chemistry & Biochemistry and ‡Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
| | - Silvina Matysiak
- Department of Chemistry & Biochemistry and ‡Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
| | - Dorothy Beckett
- Department of Chemistry & Biochemistry and ‡Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
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30
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Wang J, Custer G, Beckett D, Matysiak S. Long Distance Modulation of Disorder-to-Order Transitions in Protein Allostery. Biochemistry 2017; 56:4478-4488. [PMID: 28718281 DOI: 10.1021/acs.biochem.7b00496] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Elucidation of the molecular details of allosteric communication between distant sites in a protein is key to understanding and manipulating many biological regulatory processes. Although protein disorder is acknowledged to play an important thermodynamic role in allostery, the molecular mechanisms by which this disorder is harnessed for long distance communication are known for a limited number of systems. Transcription repression by the Escherichia coli biotin repressor, BirA, is allosterically activated by binding of the small molecule effector biotinoyl-5'-AMP. The effector acts by promoting BirA dimerization, which is a prerequisite for sequence-specific binding to the biotin biosynthetic operon operator sequence. A 30 Å distance separates the effector binding and dimerization surfaces in BirA, and previous studies indicate that allostery is mediated, in part, by disorder-to-order transitions on the two coupled sites. In this work, combined experimental and computational methods have been applied to investigate the molecular basis of allosteric communication in BirA. Double-mutant cycle analysis coupled with thermodynamic measurements indicates functional coupling between residues in disordered loops on the two distant surfaces. All atom molecular dynamics simulations reveal that this coupling occurs through long distance reciprocal modulation of the structure and dynamics of disorder-to-order transitions on the two surfaces.
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Affiliation(s)
- Jingheng Wang
- Fischell Department of Bioengineering and ‡Department of Chemistry & Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Gregory Custer
- Fischell Department of Bioengineering and ‡Department of Chemistry & Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Dorothy Beckett
- Fischell Department of Bioengineering and ‡Department of Chemistry & Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Silvina Matysiak
- Fischell Department of Bioengineering and ‡Department of Chemistry & Biochemistry, University of Maryland , College Park, Maryland 20742, United States
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31
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Hauser K, He Y, Garcia-Diaz M, Simmerling C, Coutsias E. Characterization of Biomolecular Helices and Their Complementarity Using Geometric Analysis. J Chem Inf Model 2017; 57:864-874. [PMID: 28287728 DOI: 10.1021/acs.jcim.6b00721] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A general method is presented to characterize the helical properties of potentially irregular helices, such as those found in protein secondary and tertiary structures and nucleic acids. The method was validated using artificial helices with varying numbers of points, points per helical turn, pitch, and radius. The sensitivity of the method was validated by applying increasing amounts of random perturbation to the coordinates of these helices; 399 360 helices in total were evaluated. In addition, the helical parameters of protein secondary structure elements and nucleic acid helices were analyzed. Generally, at least seven points were required to recapitulate the parameters of a helix using our method. The method can also be used to calculate the helical parameters of nucleic acid-binding proteins, like TALE, enabling direct analysis of their helix complementarity to sequence-dependent DNA distortions.
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Affiliation(s)
- Kevin Hauser
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794, United States
| | - Yiqing He
- Great Neck South High School , Great Neck, New York 11023, United States
| | - Miguel Garcia-Diaz
- Department of Pharmacological Sciences, Stony Brook University , Stony Brook, New York 11794, United States
| | - Carlos Simmerling
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794, United States.,Laufer Center for Physical and Quantitative Biology, Stony Brook University , Stony Brook, New York 11794, United States
| | - Evangelos Coutsias
- Laufer Center for Physical and Quantitative Biology, Stony Brook University , Stony Brook, New York 11794, United States.,Department of Applied Mathematics and Statistics, Stony Brook University , Stony Brook, New York 11794, United States
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32
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Tomsett M, Maffucci I, Le Bailly BAF, Byrne L, Bijvoets SM, Lizio MG, Raftery J, Butts CP, Webb SJ, Contini A, Clayden J. A tendril perversion in a helical oligomer: trapping and characterizing a mobile screw-sense reversal. Chem Sci 2017; 8:3007-3018. [PMID: 28451368 PMCID: PMC5380885 DOI: 10.1039/c6sc05474a] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/24/2017] [Indexed: 11/21/2022] Open
Abstract
Helical oligomers of achiral monomers adopt domains of uniform screw sense, which are occasionally interrupted by screw-sense reversals. These rare, elusive, and fast-moving features have eluded detailed characterization. We now describe the structure and habits of a screw-sense reversal trapped within a fragment of a helical oligoamide foldamer of the achiral quaternary amino acid 2-aminoisobutyric acid (Aib). The reversal was enforced by compelling the amide oligomer to adopt a right-handed screw sense at one end and a left-handed screw sense at the other. The trapped reversal was characterized by X-ray crystallography, and its dynamic properties were monitored by NMR and circular dichroism, and modelled computationally. Raman spectroscopy indicated that a predominantly helical architecture was maintained despite the reversal. NMR and computational results indicated a stepwise shift from one screw sense to another on moving along the helical chain, indicating that in solution the reversal is not localised at a specific location, but is free to migrate across a number of residues. Analogous unconstrained screw-sense reversals that are free to move within a helical structure are likely to provide the mechanism by which comparable helical polymers and foldamers undergo screw-sense inversion.
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Affiliation(s)
- Michael Tomsett
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - Irene Maffucci
- Dipartimento di Scienze Farmaceutiche - Sezione di Chimica Generale e Organica "Alessandro Marchesini" , Università degli Studi di Milano , Via Venezian , 21 20133 Milano , Italy
| | - Bryden A F Le Bailly
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - Liam Byrne
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - Stefan M Bijvoets
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - M Giovanna Lizio
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess St , Manchester M1 7DN , UK
| | - James Raftery
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - Craig P Butts
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - Simon J Webb
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess St , Manchester M1 7DN , UK
| | - Alessandro Contini
- Dipartimento di Scienze Farmaceutiche - Sezione di Chimica Generale e Organica "Alessandro Marchesini" , Università degli Studi di Milano , Via Venezian , 21 20133 Milano , Italy
| | - Jonathan Clayden
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
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33
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Bottorf L, Rafferty S, Sahu ID, McCarrick RM, Lorigan GA. Utilizing Electron Spin Echo Envelope Modulation To Distinguish between the Local Secondary Structures of an α-Helix and an Amphipathic 3 10-Helical Peptide. J Phys Chem B 2017; 121:2961-2967. [PMID: 28339206 DOI: 10.1021/acs.jpcb.7b00626] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electron spin echo envelope modulation (ESEEM) spectroscopy was used to distinguish between the local secondary structures of an α-helix and a 310-helix. Previously, we have shown that ESEEM spectroscopy in combination with site-directed spin labeling (SDSL) and 2H-labeled amino acids (i) can probe the local secondary structure of α-helices, resulting in an obvious deuterium modulation pattern, where i+4 positions generally show larger 2H ESEEM peak intensities than i+3 positions. Here, we have hypothesized that due to the unique turn periodicities of an α-helix (3.6 residues per turn with a pitch of 5.4 Å) and a 310-helix (3.1 residues per turn with a pitch of 5.8-6.0 Å), the opposite deuterium modulation pattern would be observed for a 310-helix. In this study, 2H-labeled d10-leucine (Leu) was substituted at a specific Leu residue (i) and a nitroxide spin label was positioned 2, 3, and 4 residues away (denoted i+2 to i+4) on an amphipathic model peptide, LRL8. When LRL8 is solubilized in trifluoroethanol (TFE), the peptide adopts an α-helical structure, and alternatively, forms a 310-helical secondary structure when incorporated into liposomes. Larger 2H ESEEM peaks in the FT frequency domain data were observed for the i+4 samples when compared to the i+3 samples for the α-helix whereas the opposite pattern was revealed for the 310-helix. These unique patterns provide pertinent local secondary structural information to distinguish between the α-helical and 310-helical structural motifs for the first time using this ESEEM spectroscopic approach with short data acquisition times (∼30 min) and small sample concentrations (∼100 μM) as well as providing more site-specific secondary structural information compared to other common biophysical approaches, such as CD.
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Affiliation(s)
- Lauren Bottorf
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Sophia Rafferty
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
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Li J, Hu Z, Beuerman R, Verma C. Molecular Environment Modulates Conformational Differences between Crystal and Solution States of Human β-Defensin 2. J Phys Chem B 2017; 121:2739-2747. [DOI: 10.1021/acs.jpcb.7b00083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jianguo Li
- Singapore Eye Research Institute, 11 Third Hospital Avenue, #06-00, Singapore 168751
- Bioinformatics Institute (A*-STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671
| | - Zhongqiao Hu
- Bioinformatics Institute (A*-STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671
| | - Roger Beuerman
- Singapore Eye Research Institute, 11 Third Hospital Avenue, #06-00, Singapore 168751
- Department
of Ophthalmology, National University of Singapore, Singapore 119074
- School of
Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459
| | - Chandra Verma
- Singapore Eye Research Institute, 11 Third Hospital Avenue, #06-00, Singapore 168751
- Bioinformatics Institute (A*-STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671
- School
of Biological Sciences, Nanyang Technological University, Singapore 637551
- Department
of Biological Sciences, National University of Singapore, Singapore 117543
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35
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Toniolo C, Crisma M, Formaggio F, Alemán C, Ramakrishnan C, Kalmankar N, Balaram P. Intramolecular backbone···backbone hydrogen bonds in polypeptide conformations. The other way around: ɛ-turn. Biopolymers 2017; 108. [DOI: 10.1002/bip.22911] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/17/2016] [Accepted: 06/29/2016] [Indexed: 01/27/2023]
Affiliation(s)
- Claudio Toniolo
- Department of Chemistry; University of Padova; Padova 35131 Italy
- Institute of Biomolecular Chemistry, Padova Unit, CNR; Padova 35131 Italy
| | - Marco Crisma
- Institute of Biomolecular Chemistry, Padova Unit, CNR; Padova 35131 Italy
| | - Fernando Formaggio
- Department of Chemistry; University of Padova; Padova 35131 Italy
- Institute of Biomolecular Chemistry, Padova Unit, CNR; Padova 35131 Italy
| | - Carlos Alemán
- Departament d'Enginyeria Quimica; ETSEIB, Universitat Politècnica de Catalunya; Barcelona 08028 Spain
| | | | - Neha Kalmankar
- National Centre for Biological Sciences (TIFR); GKVK Campus Bangalore 560065 India
| | - Padmanabhan Balaram
- Molecular Biophysics Unit; Indian Institute of Science; Bangalore 560012 India
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36
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Sajeevan KA, Roy D. Temperature-dependent molecular dynamics study reveals an ionic liquid induced 3 10 - to α-helical switch in a neurotoxin. Biopolymers 2016; 108. [PMID: 28009043 DOI: 10.1002/bip.23009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 11/29/2016] [Accepted: 12/06/2016] [Indexed: 02/01/2023]
Abstract
Thermal melting and recooling of AuIB, a neurotoxic conopeptide and a highly potent nonaddictive pain reliever is investigated thoroughly in water and an ionic liquid (IL) 1-butyl-3-methylimidazolium Chloride, [Im41 ][Cl] by classical molecular dynamics simulations. Structural evolution of AuIB in water and the IL is observed at different temperatures between 305 and 400 K, to explore how highly viscous ionic solvents affect the peptide structure as compared to conventional solvent water. At 305 K, unlike water, the coercive effect of IL frustrates AuIB secondary structural motifs significantly. As the temperature is raised, a very interesting IL induced conformational transition from 310 - to α-helix is noticed in the peptide, presumably triggered by a significant restructuring of the peptide H-bond network. The backbone length distributions of the peptide indicate that the IL induced conformational switching is accompanied by a reduction of the axial rise of the helical region, encompassing the residues Pro-6 to Ala-10. Further, we estimated the void space available to the peptide for its structural relaxation within the first solvation shell of ∼5 Å in water as well as in IL. A temperature increase by 100 K, opens up an estimated void volume of ∼70 Å3 , equivalent to the volume of approximately six water molecules, around the peptide in IL. Cooling simulations of AuIB point to the crucial interplay between thermodynamically favored AuIB conformers and their kinetic control. This study provides a comprehensive understanding of the ionic solvation of biomolecules reinforcing previous experimental findings.
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Affiliation(s)
- Karuna Anna Sajeevan
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Hyderabad, Campus, Jawahar Nagar, Shameerpet Mandal, Hyderabad, Telangana, 500078, India
| | - Durba Roy
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Hyderabad, Campus, Jawahar Nagar, Shameerpet Mandal, Hyderabad, Telangana, 500078, India
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37
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Manna M, Kulig W, Javanainen M, Tynkkynen J, Hensen U, Müller DJ, Rog T, Vattulainen I. How To Minimize Artifacts in Atomistic Simulations of Membrane Proteins, Whose Crystal Structure Is Heavily Engineered: β₂-Adrenergic Receptor in the Spotlight. J Chem Theory Comput 2016; 11:3432-45. [PMID: 26575777 DOI: 10.1021/acs.jctc.5b00070] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Atomistic molecular dynamics (MD) simulations are used extensively to elucidate membrane protein properties. These simulations are based on three-dimensional protein structures that in turn are often based on crystallography. The protein structures resolved in crystallographic studies typically do not correspond to pristine proteins, however. Instead the crystallized proteins are commonly engineered, including structural modifications (mutations, replacement of protein sequences by antibodies, bound ligands, etc.) whose impact on protein structure and dynamics is largely unknown. Here we explore this issue through atomistic MD simulations (∼5 μs in total), focusing on the β2-adrenergic receptor (β2AR) that is one of the most studied members of the G-protein coupled receptor superfamily. Starting from an inactive-state crystal structure of β2AR, we remove the many modifications in β2AR systematically one at a time, in six consecutive steps. After each step, we equilibrate the system and simulate it quite extensively. The results of this step-by-step approach highlight that the structural modifications used in crystallization can affect ligand and G-protein binding sites, packing at the transmembrane-helix interface region, and the dynamics of connecting loops in β2AR. When the results of the systematic step-by-step approach are compared to an all-at-once technique where all modifications done on β2AR are removed instantaneously at the same time, it turns out that the step-by-step method provides results that are superior in terms of maintaining protein structural stability. The results provide compelling evidence that for membrane proteins whose 3D structure is based on structural engineering, the preparation of protein structure for atomistic MD simulations is a delicate and sensitive process. The results show that most valid results are found when the structural modifications are reverted slowly, one at a time.
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Affiliation(s)
- Moutusi Manna
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Waldemar Kulig
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Matti Javanainen
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Joona Tynkkynen
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Ulf Hensen
- Department of Biosystems Science and Engineering (D-BSSE), ETH-Zürich , 4058 Basel, Switzerland
| | - Daniel J Müller
- Department of Biosystems Science and Engineering (D-BSSE), ETH-Zürich , 4058 Basel, Switzerland
| | - Tomasz Rog
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Ilpo Vattulainen
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.,MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark , Odense, Denmark
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38
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Stojanoski V, Adamski CJ, Hu L, Mehta SC, Sankaran B, Zwart P, Prasad BVV, Palzkill T. Removal of the Side Chain at the Active-Site Serine by a Glycine Substitution Increases the Stability of a Wide Range of Serine β-Lactamases by Relieving Steric Strain. Biochemistry 2016; 55:2479-90. [PMID: 27073009 DOI: 10.1021/acs.biochem.6b00056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Serine β-lactamases are bacterial enzymes that hydrolyze β-lactam antibiotics. They utilize an active-site serine residue as a nucleophile, forming an acyl-enzyme intermediate during hydrolysis. In this study, thermal denaturation experiments as well as X-ray crystallography were performed to test the effect of substitution of the catalytic serine with glycine on protein stability in serine β-lactamases. Six different enzymes comprising representatives from each of the three classes of serine β-lactamases were examined, including TEM-1, CTX-M-14, and KPC-2 of class A, P99 of class C, and OXA-48 and OXA-163 of class D. For each enzyme, the wild type and a serine-to-glycine mutant were evaluated for stability. The glycine mutants all exhibited enhanced thermostability compared to that of the wild type. In contrast, alanine substitutions of the catalytic serine in TEM-1, OXA-48, and OXA-163 did not alter stability, suggesting removal of the Cβ atom is key to the stability increase associated with the glycine mutants. The X-ray crystal structures of P99 S64G, OXA-48 S70G and S70A, and OXA-163 S70G suggest that removal of the side chain of the catalytic serine releases steric strain to improve enzyme stability. Additionally, analysis of the torsion angles at the nucleophile position indicates that the glycine mutants exhibit improved distance and angular parameters of the intrahelical hydrogen bond network compared to those of the wild-type enzymes, which is also consistent with increased stability. The increased stability of the mutants indicates that the enzyme pays a price in stability for the presence of a side chain at the catalytic serine position but that the cost is necessary in that removal of the serine drastically impairs function. These findings support the stability-function hypothesis, which states that active-site residues are optimized for substrate binding and catalysis but that the requirements for catalysis are often not consistent with the requirements for optimal stability.
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Affiliation(s)
| | | | | | | | - Banumathi Sankaran
- Berkeley Center for Structural Biology, Molecular Biophysics and Integrated Bioimaging, Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Peter Zwart
- Berkeley Center for Structural Biology, Molecular Biophysics and Integrated Bioimaging, Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
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39
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Deluca SH, Rathmann D, Beck-Sickinger AG, Meiler J. The activity of prolactin releasing peptide correlates with its helicity. Biopolymers 2016; 99:314-25. [PMID: 23426574 DOI: 10.1002/bip.22162] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 08/30/2012] [Accepted: 09/15/2012] [Indexed: 11/09/2022]
Abstract
The prolactin releasing peptide (PrRP) is involved in regulating food intake and body weight homeostasis, but molecular details on the activation of the PrRP receptor remain unclear. C-terminal segments of PrRP with 20 (PrRP20) and 13 (PrRP8-20) amino acids, respectively, have been suggested to be fully active. The data presented herein indicate this is true for the wildtype receptor only; a 5-10-fold loss of activity was found for PrRP8-20 compared to PrRP20 at two extracellular loop mutants of the receptor. To gain insight into the secondary structure of PrRP, we used CD spectroscopy performed in TFE and SDS. Additionally, previously reported NMR data, combined with ROSETTANMR, were employed to determine the structure of amidated PrRP20. The structural ensemble agrees with the spectroscopic data for the full-length peptide, which exists in an equilibrium between α- and 3(10)-helix. We demonstrate that PrRP8-20's reduced propensity to form an α-helix correlates with its reduced biological activity on mutant receptors. Further, distinct amino acid replacements in PrRP significantly decrease affinity and activity but have no influence on the secondary structure of the peptide. We conclude that formation of a primarily α-helical C-terminal region of PrRP is critical for receptor activation.
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Affiliation(s)
- Stephanie H Deluca
- Vanderbilt University Center for Structural Biology, 5144B Biosci/MRBIII, 465 21st Avenue South, Nashville, TN 37232-8725
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40
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Milov AD, Tsvetkov YD, Raap J, De Zotti M, Formaggio F, Toniolo C. Review conformation, self-aggregation, and membrane interaction of peptaibols as studied by pulsed electron double resonance spectroscopy. Biopolymers 2016; 106:6-24. [DOI: 10.1002/bip.22713] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/29/2015] [Accepted: 08/09/2015] [Indexed: 12/15/2022]
Affiliation(s)
- Alexander D. Milov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion; Novosibirsk 630090 Russian Federation
| | - Yuri D. Tsvetkov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion; Novosibirsk 630090 Russian Federation
| | - Jan Raap
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University; 2300 RA Leiden The Netherlands
| | - Marta De Zotti
- Department of Chemistry; University of Padova; Padova 35131 Italy
| | | | - Claudio Toniolo
- Department of Chemistry; University of Padova; Padova 35131 Italy
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41
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Appadu A, Jelokhani-Niaraki M, DeBruin L. Conformational Changes and Association of Membrane-Interacting Peptides in Myelin Membrane Models: A Case of the C-Terminal Peptide of Proteolipid Protein and the Antimicrobial Peptide Melittin. J Phys Chem B 2015; 119:14821-30. [DOI: 10.1021/acs.jpcb.5b07375] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ashtina Appadu
- Department
of Chemistry and
Biochemistry, Wilfrid Laurier University, 75 University Ave. W., Waterloo, Ontario, Canada N2L 3C5
| | - Masoud Jelokhani-Niaraki
- Department
of Chemistry and
Biochemistry, Wilfrid Laurier University, 75 University Ave. W., Waterloo, Ontario, Canada N2L 3C5
| | - Lillian DeBruin
- Department
of Chemistry and
Biochemistry, Wilfrid Laurier University, 75 University Ave. W., Waterloo, Ontario, Canada N2L 3C5
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42
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Brown JW, Bullitt E, Sriswasdi S, Harper S, Speicher DW, McKnight CJ. The Physiological Molecular Shape of Spectrin: A Compact Supercoil Resembling a Chinese Finger Trap. PLoS Comput Biol 2015; 11:e1004302. [PMID: 26067675 PMCID: PMC4466138 DOI: 10.1371/journal.pcbi.1004302] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 04/27/2015] [Indexed: 01/29/2023] Open
Abstract
The primary, secondary, and tertiary structures of spectrin are reasonably well defined, but the structural basis for the known dramatic molecular shape change, whereby the molecular length can increase three-fold, is not understood. In this study, we combine previously reported biochemical and high-resolution crystallographic data with structural mass spectroscopy and electron microscopic data to derive a detailed, experimentally-supported quaternary structure of the spectrin heterotetramer. In addition to explaining spectrin’s physiological resting length of ~55-65 nm, our model provides a mechanism by which spectrin is able to undergo a seamless three-fold extension while remaining a linear filament, an experimentally observed property. According to the proposed model, spectrin’s quaternary structure and mechanism of extension is similar to a Chinese Finger Trap: at shorter molecular lengths spectrin is a hollow cylinder that extends by increasing the pitch of each spectrin repeat, which decreases the internal diameter. We validated our model with electron microscopy, which demonstrated that, as predicted, spectrin is hollow at its biological resting length of ~55-65 nm. The model is further supported by zero-length chemical crosslink data indicative of an approximately 90 degree bend between adjacent spectrin repeats. The domain-domain interactions in our model are entirely consistent with those present in the prototypical linear antiparallel heterotetramer as well as recently reported inter-strand chemical crosslinks. The model is consistent with all known physical properties of spectrin, and upon full extension our Chinese Finger Trap Model reduces to the ~180-200 nm molecular model currently in common use. Spectrins are cytoskeletal and scaffolding proteins ubiquitously expressed in essentially all cell-types. Despite unequivocal evidence for a short physiological length of ~55–65 nm at rest, spectrin is typically represented as an extended ~200 nm molecule that is implied based on crystallographic structures of a number of tandem repeats. Here, we incorporate previously reported biochemical and crystallographic data with structural mass spectroscopy and electron microscopic data to derive a detailed, experimentally-supported quaternary structure of the physiological compact form of spectrin. In addition to explaining spectrin’s physiological resting length (~55–65 nm), our model provides a mechanism by which spectrin can undergo a seamless three-fold extension, which is an experimentally observed property that is responsible for restoration of cell shape after mechanical deformation.
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Affiliation(s)
- Jeffrey W. Brown
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Internal Medicine Residency Program, University of Pittsburgh Medical Center, UPMC Montefiore Hospital, Pittsburgh, Pennsylvania, United States of America
| | - Esther Bullitt
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Sira Sriswasdi
- Center for Systems and Computational Biology, and Molecular and Cellular Oncogenesis Program, the Wistar Institute, Philadelphia, Pennsylvania, United States of America
- Genomics and Computational Biology Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sandra Harper
- Center for Systems and Computational Biology, and Molecular and Cellular Oncogenesis Program, the Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - David W. Speicher
- Center for Systems and Computational Biology, and Molecular and Cellular Oncogenesis Program, the Wistar Institute, Philadelphia, Pennsylvania, United States of America
- Genomics and Computational Biology Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - C. James McKnight
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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43
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Kumari JLJ, Sudandiradoss C. Exploring the structural constraints at cleavage site of mucin 1 isoform through molecular dynamics simulation. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:309-23. [DOI: 10.1007/s00249-015-1023-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/13/2015] [Accepted: 03/20/2015] [Indexed: 12/19/2022]
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44
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Schubert F, Pagel K, Rossi M, Warnke S, Salwiczek M, Koksch B, von Helden G, Blum V, Baldauf C, Scheffler M. Native like helices in a specially designed β peptide in the gas phase. Phys Chem Chem Phys 2015; 17:5376-85. [DOI: 10.1039/c4cp05216a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
First principles simulations and gas phase spectroscopy suggest equilibrium of helices for an oligomer of open chain β amino acids.
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Affiliation(s)
| | - Kevin Pagel
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- D-14195 Berlin
- Germany
- Institut für Chemie und Biochemie
- Freie Universität Berlin
| | - Mariana Rossi
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- D-14195 Berlin
- Germany
- Physical and Theoretical Chemistry Laboratory
- University of Oxford
| | - Stephan Warnke
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- D-14195 Berlin
- Germany
| | - Mario Salwiczek
- Institut für Chemie und Biochemie
- Freie Universität Berlin
- D-14195 Berlin
- Germany
| | - Beate Koksch
- Institut für Chemie und Biochemie
- Freie Universität Berlin
- D-14195 Berlin
- Germany
| | - Gert von Helden
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- D-14195 Berlin
- Germany
| | - Volker Blum
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- D-14195 Berlin
- Germany
- Mechanical Engineering and Material Science Department and Center for Materials Genomics
- Duke University
| | - Carsten Baldauf
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- D-14195 Berlin
- Germany
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45
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Sonawane KD, Barage SH. Structural analysis of membrane-bound hECE-1 dimer using molecular modeling techniques: insights into conformational changes and Aβ1–42 peptide binding. Amino Acids 2014; 47:543-59. [DOI: 10.1007/s00726-014-1887-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 11/28/2014] [Indexed: 10/24/2022]
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46
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The influence of flanking secondary structures on amino Acid content and typical lengths of 3/10 helices. INTERNATIONAL JOURNAL OF PROTEOMICS 2014; 2014:360230. [PMID: 25371821 PMCID: PMC4211214 DOI: 10.1155/2014/360230] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/19/2014] [Accepted: 09/27/2014] [Indexed: 11/25/2022]
Abstract
We used 3D structures of a highly redundant set of bacterial proteins encoded by genes of high, average, and low GC-content. Four types of connecting bridges—regions situated between any of two major elements of secondary structure (alpha helices and beta strands)—containing a pure random coil were compared with connecting bridges containing 3/10 helices. We included discovered trends in the original “VVTAK Connecting Bridges” algorithm, which is able to predict more probable conformation for a given connecting bridge. The highest number of significant differences in amino acid usage was found between 3/10 helices containing bridges connecting two beta strands (they have increased Phe, Tyr, Met, Ile, Leu, Val, and His usages but decreased usages of Asp, Asn, Gly, and Pro) and those without 3/10 helices. The typical (most common) length of 3/10 helices situated between two beta strands and between beta strand and alpha helix is equal to 5 amino acid residues. The preferred length of 3/10 helices situated between alpha helix and beta strand is equal to 3 residues. For 3/10 helices situated between two alpha helices, both lengths (3 and 5 amino acid residues) are typical.
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47
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Tsigelny IF, Sharikov Y, Kouznetsova VL, Greenberg JP, Wrasidlo W, Gonzalez T, Desplats P, Michael SE, Trejo-Morales M, Overk CR, Masliah E. Structural diversity of Alzheimer's disease amyloid-β dimers and their role in oligomerization and fibril formation. J Alzheimers Dis 2014; 39:583-600. [PMID: 24240640 DOI: 10.3233/jad-131589] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Alzheimer's disease (AD) is associated with the formation of toxic amyloid-β (Aβ)42 oligomers, and recent evidence supports a role for Aβ dimers as building blocks for oligomers. Molecular dynamics simulation studies have identified clans for the dominant conformations of Aβ42 forming dimers; however, it is unclear if a larger spectrum of dimers is involved and which set(s) of dimers might evolve to oligomers verse fibrils. Therefore, for this study we generated multiple structural conformations of Aβ42, using explicit all-atom molecular dynamics, and then clustering the different structures based on key conformational similarities. Those matching a selection threshold were then used to model a process of oligomerization. Remarkably, we showed a greater diversity in Aβ dimers than previously described. Depending on the clan family, different types of Aβ dimers were obtained. While some had the tendency to evolve into oligomeric rings, others formed fibrils of diverse characteristics. Then we selected the dimers that would evolve to membranephilic annular oligomers. Nearly one third of the 28 evaluated annular oligomers had the dimer interfaces between the neighboring Aβ42 monomers with possible salt bridges between the residue K28 from one side and either residue E22 or D23 on the other. Based on these results, key amino acids were identified for point mutations that either enhanced or suppressed the formation and toxicity of oligomer rings. Our studies suggest a greater diversity of Aβ dimers. Understanding the structure of Aβ dimers might be important for the rationale design of small molecules that block formation of toxic oligomers.
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Affiliation(s)
- Igor F Tsigelny
- San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA, USA Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Yuriy Sharikov
- San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA, USA Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Valentina L Kouznetsova
- San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA, USA Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA
| | - Jerry P Greenberg
- San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA, USA
| | - Wolfgang Wrasidlo
- Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Tania Gonzalez
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Paula Desplats
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Sarah E Michael
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | | | - Cassia R Overk
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Eliezer Masliah
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA Department of Pathology, University of California, San Diego, La Jolla, CA, USA
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48
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Bradshaw M, Gaffney BJ. Fluctuations of an exposed π-helix involved in lipoxygenase substrate recognition. Biochemistry 2014; 53:5102-10. [PMID: 25036469 PMCID: PMC4131896 DOI: 10.1021/bi500768c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 07/16/2014] [Indexed: 01/14/2023]
Abstract
The second helix in lipoxygenases adapts to permit substrate access to the active site, but details of this process are varied and poorly understood. We therefore examined the dynamics of helix 2 in solutions of spin-labeled soybean lipoxygenase-1 and spin relaxation at 60 K of the spin-labels by catalytic iron. Helix 2 in soybean lipoxygenase structures is surface-exposed and contains one turn of π-helix, centrally located. A site-directed spin-label scan of 18 of the 21 helix 2 residues, and electron paramagnetic resonance, showed that the π-helical segment became unusually mobile, on a nanosecond time scale, under conditions favoring substrate binding (pH 9 and lipid addition), while segments before and after had relatively unchanged dynamics. Backbone dynamics of residues in the π-helical segment appeared to be correlated, at pH 9. Samples also were frozen to examine the polarity and proticity of the local environments, the effect of the local environment on intrinsic relaxation, and dipolar relaxation by two symmetries of catalytic iron. The average hyperfine tensor component, Azz, of four π-helix residues decreased by 1.75 G, with an increase in pH from 7 to 9, while it remained unaffected for nearby buried residues. Power saturation data suggested the change in polarity specific to the π-helix altered the intrinsic relaxation rates. Different symmetries of iron contributed to distance-dependent magnetic relaxation. We interpret these data to mean that a π-helix in the second helix of plant lipoxygenases is highly dynamic and is the site where lipid chains penetrate to inner helices that outline the substrate pocket.
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Affiliation(s)
- Miles
D. Bradshaw
- Department
of Biological
Science, Florida State University, Tallahassee, Florida 32306-4295, United States
| | - Betty J. Gaffney
- Department
of Biological
Science, Florida State University, Tallahassee, Florida 32306-4295, United States
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49
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Zhang L, Buck M. Molecular simulations of a dynamic protein complex: role of salt-bridges and polar interactions in configurational transitions. Biophys J 2014; 105:2412-7. [PMID: 24268153 DOI: 10.1016/j.bpj.2013.09.052] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 08/23/2013] [Accepted: 09/24/2013] [Indexed: 12/29/2022] Open
Abstract
Ion charge pairs and hydrogen bonds have been extensively studied for their roles in stabilizing protein complexes and in steering the process of protein association. Recently, it has become clear that some protein complexes are dynamic in that they interconvert between several alternate configurations. We have previously characterized one such system: the EphA2:SHIP2 SAM-SAM heterodimer by solution NMR. Here we carried out extensive all-atom molecular-dynamics simulations on a microsecond time-scale starting with different NMR-derived structures for the complex. Transitions are observed between several discernible configurations at average time intervals of 50-100 ns. The domains reorient relative to one another by substantial rotation and a slight shifting of the interfaces. Bifurcated and intermediary salt-bridge and hydrogen-bond interactions play a role in the transitions in a process that can be described as moving along a "monkey-bar". We notice an increased density of salt bridges near protein interaction surfaces that appear to enable these transitions, also suggesting why the trajectories can become kinetically hindered in regions where fewer of such interactions are possible. In this context, even microsecond molecular-dynamics simulations are not sufficient to sample the energy landscape unless the structures remain close to their experimentally derived low-energy configurations.
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Affiliation(s)
- Liqun Zhang
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, Cleveland, Ohio
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50
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Eagleburger MK, Cooley JW, JiJi RD. Effects of fluidity on the ensemble structure of a membrane embedded α‐helical peptide. Biopolymers 2014; 101:895-902. [DOI: 10.1002/bip.22472] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/09/2014] [Indexed: 01/23/2023]
Affiliation(s)
- Michael K. Eagleburger
- Department of ChemistryUniversity of Missouri601 S College Ave, 125 Chemistry BuildingColumbia MO65211
| | - Jason W. Cooley
- Department of ChemistryUniversity of Missouri601 S College Ave, 125 Chemistry BuildingColumbia MO65211
| | - Renee D. JiJi
- Department of ChemistryUniversity of Missouri601 S College Ave, 125 Chemistry BuildingColumbia MO65211
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