1
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Jones SA, Ruprecht JJ, Crichton PG, Kunji ERS. Structural mechanisms of mitochondrial uncoupling protein 1 regulation in thermogenesis. Trends Biochem Sci 2024; 49:506-519. [PMID: 38565497 DOI: 10.1016/j.tibs.2024.03.005] [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: 12/05/2023] [Revised: 02/28/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024]
Abstract
In mitochondria, the oxidation of nutrients is coupled to ATP synthesis by the generation of a protonmotive force across the mitochondrial inner membrane. In mammalian brown adipose tissue (BAT), uncoupling protein 1 (UCP1, SLC25A7), a member of the SLC25 mitochondrial carrier family, dissipates the protonmotive force by facilitating the return of protons to the mitochondrial matrix. This process short-circuits the mitochondrion, generating heat for non-shivering thermogenesis. Recent cryo-electron microscopy (cryo-EM) structures of human UCP1 have provided new molecular insights into the inhibition and activation of thermogenesis. Here, we discuss these structures, describing how purine nucleotides lock UCP1 in a proton-impermeable conformation and rationalizing potential conformational changes of this carrier in response to fatty acid activators that enable proton leak for thermogenesis.
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Affiliation(s)
- Scott A Jones
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Keith Peters Building, Cambridge, CB2 0XY, UK
| | - Jonathan J Ruprecht
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Keith Peters Building, Cambridge, CB2 0XY, UK
| | - Paul G Crichton
- Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Edmund R S Kunji
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Keith Peters Building, Cambridge, CB2 0XY, UK.
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2
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Sen C, Logashree V, Makde RD, Ghosh B. Amino acid propensities for secondary structures and its variation across protein structures using exhaustive PDB data. Comput Biol Chem 2024; 110:108083. [PMID: 38691894 DOI: 10.1016/j.compbiolchem.2024.108083] [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: 11/03/2023] [Revised: 03/26/2024] [Accepted: 04/23/2024] [Indexed: 05/03/2024]
Abstract
Amino acid propensities for protein secondary structures are vital for protein structure prediction, understanding folding, and design, and have been studied using various theoretical and experimental methods. Traditional assessments of average propensities using statistical methods have been done on relatively smaller dataset for only a few secondary structures. They also involve averaging out the environmental factors and lack insights into consistency of preferences across diverse protein structures. While a few studies have explored variations in propensities across protein structural classes and folds, exploration of such variations across protein structures remains to be carried out. In this work, we have revised the average propensities for all six different secondary structures, namely α-helix, β-strand, 310-helix, π-helix, turn and coil, analyzing the most exhaustive dataset available till date using two robust secondary structure assignment algorithms, DSSP and STRIDE. The propensities evaluated here can serve as a standard reference. Moreover, we present here, for the first time, the propensities within individual protein structures and investigated how the preferences of residues and more interestingly, of their groups formed based on their structural features, vary across different unique structures. We devised a novel approach- the minimal set analysis, based on the propensity distribution of residues, which along with the group propensities led us to the conclusion that a residue's preference for a specific secondary structure is primarily dictated by its side chain's structural features. The findings in this study provide a more insightful picture of residues propensities and can be useful in protein folding and design studies.
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Affiliation(s)
- Chandra Sen
- Beamline Development & Application Section, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - V Logashree
- Department of Electrical Engineering, Indian Institute of Technology, Indore 453552, India
| | - Ravindra D Makde
- Beamline Development & Application Section, Bhabha Atomic Research Centre, Mumbai 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Biplab Ghosh
- Beamline Development & Application Section, Bhabha Atomic Research Centre, Mumbai 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India.
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3
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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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4
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Jhinjharia D, Kaushik AC, Sahi S. A high-throughput structural dynamics approach for identification of potential agonists of FFAR4 for type 2 diabetes mellitus therapy. J Biomol Struct Dyn 2023:1-21. [PMID: 37978906 DOI: 10.1080/07391102.2023.2280707] [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: 05/23/2023] [Accepted: 11/02/2023] [Indexed: 11/19/2023]
Abstract
Diabetes mellitus is a metabolic disorder that persists as a global threat to the world. A G-protein coupled receptor (GPCR), free fatty acid receptor 4 (FFAR4), has emerged as a potential target for type 2 diabetes mellitus (T2DM) and obesity-related disorders. The current study has investigated the FFAR4, deploying 3-dimensional structure modeling, molecular docking, machine learning, and high-throughput virtual screening methods to unravel the receptor's crucial and non-crucial binding site residues. We screened four lakh compounds and shortlisted them based on binding energy, stereochemical considerations, non-bonded interactions, and pharmacokinetic profiling. Out of the screened compounds, four compounds were selected for ligand-bound simulations. The molecular dynamic simulations were carried out for 1µs for native FFAR4 and 500 ns each for complexes of FFAR4 with compound 1, compound 2, compound 3, and compound 4. Our findings showed that in addition to reported binding site residues ARG99, ARG183, and VAL98 in known agonists like TUG-891, the amino acids ARG22, ARG24, THR23, TRP305, and GLU43 were also critical binding site residues. These amino acids impart stability to the FFAR4 complexes and contribute to the stronger binding affinity of the compounds. The study also indicated that aromatic residues like PHE211 are crucial for recognizing the active site's pi-pi and C-C double bonds. Since FFAR4 is a membrane protein, the simulation studies give an insight into the mechanisms of the crucial protein-lipid and lipid-water interactions. The analysis of the molecular dynamics trajectories showed all four compounds as potential hit molecules that can be developed further into potential agonists for T2DM therapy. Amongst the four compounds, compound 4 showed relatively better binding affinity, stronger non-bonded interactions, and a stable complex.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Divya Jhinjharia
- School of Biotechnology, Gautam Buddha University, Greater Noida, India
| | - Aman Chandra Kaushik
- Department of Bioinformatics and Biological Statistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Shakti Sahi
- School of Biotechnology, Gautam Buddha University, Greater Noida, India
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5
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Arnittali M, Rissanou AN, Kefala A, Kokkinidis M, Harmandaris V. Structure of amino acid sequence-reversed wtRop protein: insights from atomistic molecular dynamics simulations. J Biomol Struct Dyn 2023:1-15. [PMID: 37671833 DOI: 10.1080/07391102.2023.2252903] [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: 05/16/2023] [Accepted: 08/23/2023] [Indexed: 09/07/2023]
Abstract
This study aims to the investigation of the advantages of designing new proteins presume upon a 'bias' sequence of amino acids, based on the reversed sequence of parent proteins, such as the retro ones. The structural simplicity of wtRop offers a very attractive model system to study these aspects. The current work is based on all-atom Molecular Dynamics (MD) simulations and corresponding experimental evidence on two different types of reversed wtRop protein, one with a fully reversed sequence of amino acids (rRop) and another with a partially reversed sequence (prRop), where only the five residues of the loop region (30ASP-34GLN) were not reversed. The exploration of the structure of the two retro proteins is performed highlighting the similarities and the differences with their parent protein, by employing various measures. Two models have been studied for both reversed proteins, a dimeric and a monomeric with the former one found to be more stable than the latter. Preferable equilibrium structures that the protein molecule can attain are explored, indicating the equilibration pathway. Simulation findings indicate a disruption of the α-helical structure and the appearance of additional secondary structures for both retro proteins. Reduced structural stability compared to their parent protein (wtRop) is also found. A corruption of the hydrophobic core is observed in the dimeric models. Furthermore, the simulations findings are consistent with the experimental characterization of prRop by circular dichroism spectroscopy (CD) which highlights an unstable, highly α-helical protein.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Maria Arnittali
- Computation-Based Science and Technology Research Center, The Cyprus Institute, Nicosia, Cyprus
- Institute of Applied and Computational Mathematics, Foundation for Research and Technology Hellas (FORTH), Heraklion, Greece
- Department of Mathematics and Applied Mathematics, University of Crete, Heraklion, Crete, Greece
| | - Anastassia N Rissanou
- National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, Athens, Greece
| | - Aikaterini Kefala
- Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology (FORTH), Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Crete, Greece
| | - Michael Kokkinidis
- Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology (FORTH), Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Crete, Greece
| | - Vagelis Harmandaris
- Computation-Based Science and Technology Research Center, The Cyprus Institute, Nicosia, Cyprus
- Institute of Applied and Computational Mathematics, Foundation for Research and Technology Hellas (FORTH), Heraklion, Greece
- Department of Mathematics and Applied Mathematics, University of Crete, Heraklion, Crete, Greece
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6
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Pal S. Impact of Hydrogen‐Bond Surrogate Model on Helix Stabilization and Development of Protein‐Protein Interaction Inhibitors. ChemistrySelect 2023. [DOI: 10.1002/slct.202204207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Affiliation(s)
- Sunit Pal
- Chemical Genomics Centre of the Max Planck Society Max Planck Institute of Molecular Physiology Otto-Hahn-Str. 11 44227 Dortmund Germany
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7
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Anticancer peptides mechanisms, simple and complex. Chem Biol Interact 2022; 368:110194. [PMID: 36195187 DOI: 10.1016/j.cbi.2022.110194] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 09/12/2022] [Accepted: 09/22/2022] [Indexed: 11/22/2022]
Abstract
Peptide therapy has started since 1920s with the advent of insulin application, and now it has emerged as a new approach in treatment of diseases including cancer. Using anti-cancer peptides (ACPs) is a promising way of cancer therapy as ACPs are continuing to be approved and arrived at major pharmaceutical markets. Traditional cancer treatments face different problems like intensive adverse effects to patient's body, cell resistance to conventional chemical drugs and in some worse cases the occurrence of cell multidrug resistance (MDR) of cancerous tissues against chemotherapy. On the other hand, there are some benefits conceived for peptides usage in treatment of diseases specifically cancer, as these compounds present favorable characteristics such as smaller size, high activity, low immunogenicity, good biocompatibility in vivo, convenient and rapid way of synthesis, amenable to sequence modification and revision and there is no limitation for the type of cargo they carry. It is possible to achieve an optimum molecular and functional structure of peptides based on previous experience and bank of peptide motif data which may result in novel peptide design. Bioactive peptides are able to form pores in cell membrane and induce necrosis or apoptosis of abnormal cells. Moreover, recent researches have focused on the tumor recognizing peptide motifs with the ability to permeate to cancerous cells with the aim of cancer treatment at earlier stages. In this strategy the most important factors for addressing cancer are choosing peptides with easy accessibility to tumor cell without cytotoxicity effect towards normal cells. The peptides must also meet acceptable pharmacokinetic requirements. In this review, the characteristics of peptides and cancer cells are discussed. The various mechanisms of peptides' action proposed against cancer cells make the next part of discussion. It will be followed by giving information on peptides application, various methods of peptide designing along with introducing various databases. Future aspects of peptides for employing in area of cancer treatment come as conclusion at the end.
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8
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Huang H, Kiick KL. Peptide-based assembled nanostructures that can direct cellular responses. Biomed Mater 2022; 17. [DOI: 10.1088/1748-605x/ac92b5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 09/16/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Natural originated materials have been well-studied over the past several decades owing to their higher biocompatibility compared to the traditional polymers. Peptides, consisting of amino acids, are among the most popular programable building blocks, which is becoming a growing interest in nanobiotechnology. Structures assembled using those biomimetic peptides allow the exploration of chemical sequences beyond those been routinely used in biology. In this Review, we discussed the most recent experimental discoveries on the peptide-based assembled nanostructures and their potential application at the cellular level such as drug delivery. In particular, we explored the fundamental principles of peptide self-assembly and the most recent development in improving their interactions with biological systems. We believe that as the fundamental knowledge of the peptide assemblies evolves, the more sophisticated and versatile nanostructures can be built, with promising biomedical applications.
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9
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Structure Prediction, Evaluation, and Validation of GPR18 Lipid Receptor Using Free Programs. Int J Mol Sci 2022; 23:ijms23147917. [PMID: 35887268 PMCID: PMC9319093 DOI: 10.3390/ijms23147917] [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: 06/03/2022] [Revised: 07/04/2022] [Accepted: 07/08/2022] [Indexed: 11/30/2022] Open
Abstract
The GPR18 receptor, often referred to as the N-arachidonylglycine receptor, although assigned (along with GPR55 and GPR119) to the new class A GPCR subfamily-lipid receptors, officially still has the status of a class A GPCR orphan. While its signaling pathways and biological significance have not yet been fully elucidated, increasing evidence points to the therapeutic potential of GPR18 in relation to immune, neurodegenerative, and cancer processes to name a few. Therefore, it is necessary to understand the interactions of potential ligands with the receptor and the influence of particular structural elements on their activity. Thus, given the lack of an experimentally solved structure, the goal of the present study was to obtain a homology model of the GPR18 receptor in the inactive state, meeting all requirements in terms of protein structure quality and recognition of active ligands. To increase the reliability and precision of the predictions, different contemporary protein structure prediction methods and software were used and compared herein. To test the usability of the resulting models, we optimized and compared the selected structures followed by the assessment of the ability to recognize known, active ligands. The stability of the predicted poses was then evaluated by means of molecular dynamics simulations. On the other hand, most of the best-ranking contemporary CADD software/platforms for its full usability require rather expensive licenses. To overcome this down-to-earth obstacle, the overarching goal of these studies was to test whether it is possible to perform the thorough CADD experiments with high scientific confidence while using only license-free/academic software and online platforms. The obtained results indicate that a wide range of freely available software and/or academic licenses allow us to carry out meaningful molecular modelling/docking studies.
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10
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Girmatsion M, Dong H, Abraha B, Mahmud A, Kasimala M, Gebremedhin H, Adhanom A, Lu G, Fangwei Y, Guo Y. A natural fluorescent protein for ciprofloxacin sensing and mechanism study using molecular docking and circular dichroism. Anal Chim Acta 2022; 1221:340082. [DOI: 10.1016/j.aca.2022.340082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/14/2022] [Accepted: 06/10/2022] [Indexed: 12/01/2022]
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11
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Jungck JR, Cebeci M. Wenxiang 3.0: Evolutionary Visualization of α, π, and 3/10 Helices. Evol Bioinform Online 2022; 18:11769343221101014. [PMID: 35668741 PMCID: PMC9163722 DOI: 10.1177/11769343221101014] [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: 01/10/2022] [Accepted: 04/28/2022] [Indexed: 11/19/2022] Open
Abstract
Wenxiang diagrams illustrate protein helices as spirals on a plane and thus have the advantage over helical wheels of being planar graphs. Wenxiang 3.0 extends the original version by adding 3 major features: (1) individual amino acid residues can be colored according to their evolutionary conservation in comparative multiple sequence alignments using CONSURF encoding; (2) α, π, and 3/10 helices can be illustrated by overlaying arcs representative of the pitches of these helices; and, (3) the physico-chemical properties of amino acids residues in the protein sequence can be re-presented by colored geometric shapes.
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Affiliation(s)
- John R Jungck
- Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA
| | - Metehan Cebeci
- Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA
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12
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Drew DL, Ahammad T, Serafin RA, Sahu ID, Khan RH, Faul E, McCarrick RM, Lorigan GA. Probing the local secondary structure of bacteriophage S 21 pinholin membrane protein using electron spin echo envelope modulation spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183836. [PMID: 34906602 DOI: 10.1016/j.bbamem.2021.183836] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 11/23/2021] [Accepted: 11/29/2021] [Indexed: 06/14/2023]
Abstract
There have recently been advances in methods for detecting local secondary structures of membrane protein using electron paramagnetic resonance (EPR). A three pulsed electron spin echo envelope modulation (ESEEM) approach was used to determine the local helical secondary structure of the small hole forming membrane protein, S21 pinholin. This ESEEM approach uses a combination of site-directed spin labeling and 2H-labeled side chains. Pinholin S21 is responsible for the permeabilization of the inner cytosolic membrane of double stranded DNA bacteriophage host cells. In this study, we report on the overall global helical structure using circular dichroism (CD) spectroscopy for the active form and the negative-dominant inactive mutant form of S21 pinholin. The local helical secondary structure was confirmed for both transmembrane domains (TMDs) for the active and inactive S21 pinholin using the ESEEM spectroscopic technique. Comparison of the ESEEM normalized frequency domain intensity for each transmembrane domain gives an insight into the α-helical folding nature of these domains as opposed to a π or 310-helix which have been observed in other channel forming proteins.
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Affiliation(s)
- Daniel L Drew
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Tanbir Ahammad
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Rachel A Serafin
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA; Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Rasal H Khan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Emily Faul
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
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13
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Nayak AR, Samsó M. Ca 2+ inactivation of the mammalian ryanodine receptor type 1 in a lipidic environment revealed by cryo-EM. eLife 2022; 11:75568. [PMID: 35257661 PMCID: PMC8947763 DOI: 10.7554/elife.75568] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 02/28/2022] [Indexed: 01/07/2023] Open
Abstract
Activation of the intracellular Ca2+ channel ryanodine receptor (RyR) triggers a cytosolic Ca2+ surge, while elevated cytosolic Ca2+ inhibits the channel in a negative feedback mechanism. Cryogenic electron microscopy of rabbit RyR1 embedded in nanodiscs under partially inactivating Ca2+ conditions revealed an open and a closed-inactivated conformation. Ca2+ binding to the high-affinity site engages the central and C-terminal domains into a block, which pries the S6 four-helix bundle open. Further rotation of this block pushes S6 toward the central axis, closing (inactivating) the channel. Main characteristics of the Ca2+-inactivated conformation are downward conformation of the cytoplasmic assembly and tightly knit subunit interface contributed by a fully occupied Ca2+ activation site, two inter-subunit resolved lipids, and two salt bridges between the EF hand domain and the S2-S3 loop validated by disease-causing mutations. The structural insight illustrates the prior Ca2+ activation prerequisite for Ca2+ inactivation and provides for a seamless transition from inactivated to closed conformations.
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Affiliation(s)
- Ashok R Nayak
- Department of Physiology and Biophysics, Virginia Commonwealth UniversityRichmondUnited States
| | - Montserrat Samsó
- Department of Physiology and Biophysics, Virginia Commonwealth UniversityRichmondUnited States
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14
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Rybicka-Jasińska K, Derr JB, Vullev VI. What defines biomimetic and bioinspired science and engineering? PURE APPL CHEM 2021. [DOI: 10.1515/pac-2021-0323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Abstract
Biomimicry, biomimesis and bioinspiration define distinctly different approaches for deepening the understanding of how living systems work and employing this knowledge to meet pressing demands in engineering. Biomimicry involves shear imitation of biological structures that most often do not reproduce the functionality that they have while in the living organisms. Biomimesis aims at reproduction of biological structure-function relationships and advances our knowledge of how different components of complex living systems work. Bioinspiration employs this knowledge in abiotic manners that are optimal for targeted applications. This article introduces and reviews these concepts in a global historic perspective. Representative examples from charge-transfer science and solar-energy engineering illustrate the evolution from biomimetic to bioinspired approaches and show their importance. Bioinspired molecular electrets, aiming at exploration of dipole effects on charge transfer, demonstrate the pintail impacts of biological inspiration that reach beyond its high utilitarian values. The abiotic character of bioinspiration opens doors for the emergence of unprecedented properties and phenomena, beyond what nature can offer.
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Affiliation(s)
| | - James B. Derr
- Department of Biochemistry , University of California , Riverside , CA , 92521 , USA
| | - Valentine I. Vullev
- Department of Biochemistry , University of California , Riverside , CA , 92521 , USA
- Department of Bioengineering , University of California , Riverside , CA , 92521 , USA
- Department of Chemistry , University of California , Riverside , CA , 92521 , USA
- Materials Science and Engineering Program , University of California , Riverside , CA , 92521 , USA
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15
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A structural signature motif enlightens the origin and diversification of nuclear receptors. PLoS Genet 2021; 17:e1009492. [PMID: 33882063 PMCID: PMC8092661 DOI: 10.1371/journal.pgen.1009492] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 05/03/2021] [Accepted: 03/15/2021] [Indexed: 12/11/2022] Open
Abstract
Nuclear receptors are ligand-activated transcription factors that modulate gene regulatory networks from embryonic development to adult physiology and thus represent major targets for clinical interventions in many diseases. Most nuclear receptors function either as homodimers or as heterodimers. The dimerization is crucial for gene regulation by nuclear receptors, by extending the repertoire of binding sites in the promoters or the enhancers of target genes via combinatorial interactions. Here, we focused our attention on an unusual structural variation of the α-helix, called π-turn that is present in helix H7 of the ligand-binding domain of RXR and HNF4. By tracing back the complex evolutionary history of the π-turn, we demonstrate that it was present ancestrally and then independently lost in several nuclear receptor lineages. Importantly, the evolutionary history of the π-turn motif is parallel to the evolutionary diversification of the nuclear receptor dimerization ability from ancestral homodimers to derived heterodimers. We then carried out structural and biophysical analyses, in particular through point mutation studies of key RXR signature residues and showed that this motif plays a critical role in the network of interactions stabilizing homodimers. We further showed that the π-turn was instrumental in allowing a flexible heterodimeric interface of RXR in order to accommodate multiple interfaces with numerous partners and critical for the emergence of high affinity receptors. Altogether, our work allows to identify a functional role for the π-turn in oligomerization of nuclear receptors and reveals how this motif is linked to the emergence of a critical biological function. We conclude that the π-turn can be viewed as a structural exaptation that has contributed to enlarging the functional repertoire of nuclear receptors. The origin of novelties is a central topic in evolutionary biology. A fundamental question is how organisms constrained by natural selection can divert from existing schemes to set up novel structures or pathways. Among the most important strategies are exaptations, which represent pre-adaptation strategies. Many examples exist in biology, at both morphological and molecular levels, such as the one reported here that focuses on an unusual structural feature called the π-turn. It is found in the structure of the most ancestral nuclear receptors RXR and HNF4. The analyses trace back the complex evolutionary history of the π-turn to more than 500 million years ago, before the Cambrian explosion and show that this feature was essential for the heterodimerization capacity of RXR. Nuclear receptor lineages that emerged later in evolution lost the π-turn. We demonstrate here that this loss in nuclear receptors that heterodimerize with RXR was critical for the emergence of high affinity receptors, such as the vitamin D and the thyroid hormone receptors. On the other hand, the conserved π-turn in RXR allowed it to accommodate multiple heterodimer interfaces with numerous partners. This structural exaptation allowed for the remarkable diversification of nuclear receptors.
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16
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Argudo PG, Giner-Casares JJ. Folding and self-assembly of short intrinsically disordered peptides and protein regions. NANOSCALE ADVANCES 2021; 3:1789-1812. [PMID: 36133101 PMCID: PMC9417027 DOI: 10.1039/d0na00941e] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/17/2021] [Indexed: 05/15/2023]
Abstract
Proteins and peptide fragments are highly relevant building blocks in self-assembly for nanostructures with plenty of applications. Intrinsically disordered proteins (IDPs) and protein regions (IDRs) are defined by the absence of a well-defined secondary structure, yet IDPs/IDRs show a significant biological activity. Experimental techniques and computational modelling procedures for the characterization of IDPs/IDRs are discussed. Directed self-assembly of IDPs/IDRs allows reaching a large variety of nanostructures. Hybrid materials based on the derivatives of IDPs/IDRs show a promising performance as alternative biocides and nanodrugs. Cell mimicking, in vivo compartmentalization, and bone regeneration are demonstrated for IDPs/IDRs in biotechnological applications. The exciting possibilities of IDPs/IDRs in nanotechnology with relevant biological applications are shown.
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Affiliation(s)
- Pablo G Argudo
- Université de Bordeaux, CNRS, Bordeaux INP, LCPO 16 Avenue Pey-Berland 33600 Pessac France
| | - Juan J Giner-Casares
- Departamento de Química Física y T. Aplicada, Instituto Universitario de Nanoquímica IUNAN, Facultad de Ciencias, Universidad de Córdoba (UCO) Campus de Rabanales, Ed. Marie Curie E-14071 Córdoba Spain
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17
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Brinkjost T, Ehrt C, Koch O, Mutzel P. SCOT: Rethinking the classification of secondary structure elements. Bioinformatics 2020; 36:2417-2428. [PMID: 31742326 DOI: 10.1093/bioinformatics/btz826] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 10/02/2019] [Accepted: 11/16/2019] [Indexed: 11/13/2022] Open
Abstract
MOTIVATION Secondary structure classification is one of the most important issues in structure-based analyses due to its impact on secondary structure prediction, structural alignment and protein visualization. There are still open challenges concerning helix and sheet assignments which are currently not addressed by a single multi-purpose software. RESULTS We introduce SCOT (Secondary structure Classification On Turns) as a novel secondary structure element assignment software which supports the assignment of turns, right-handed α-, 310- and π-helices, left-handed α- and 310-helices, 2.27- and polyproline II helices, β-sheets and kinks. We demonstrate that the introduction of helix Purity values enables a clear differentiation between helix classes. SCOT's unique strengths are highlighted by comparing it to six state-of-the-art methods (DSSP, STRIDE, ASSP, SEGNO, DISICL and SHAFT). The assignment approaches were compared concerning geometric consistency, protein structure quality and flexibility dependency and their impact on secondary structure element-based structural alignments. We show that only SCOT's combination of hydrogen bonds, geometric criteria and dihedral angles enables robust assignments independent of the structure quality and flexibility. We demonstrate that this combination and the elaborate kink detection lead to SCOT's clear superiority for protein alignments. As the resulting helices and strands are provided in a PDB conform output format, they can immediately be used for structure alignment algorithms. Taken together, the application of our new method and the straight-forward visualization using the accompanying PyMOL scripts enable the comprehensive analysis of regular backbone geometries in proteins. AVAILABILITY AND IMPLEMENTATION https://this-group.rocks. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Tobias Brinkjost
- Department of Computer Science.,Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund 44227, Germany
| | - Christiane Ehrt
- Department of Computer Science.,Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund 44227, Germany
| | - Oliver Koch
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund 44227, Germany
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18
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de Brevern AG. Impact of protein dynamics on secondary structure prediction. Biochimie 2020; 179:14-22. [PMID: 32946990 DOI: 10.1016/j.biochi.2020.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 09/04/2020] [Accepted: 09/10/2020] [Indexed: 02/08/2023]
Abstract
Protein 3D structures support their biological functions. As the number of protein structures is negligible in regards to the number of available protein sequences, prediction methodologies relying only on protein sequences are essential tools. In this field, protein secondary structure prediction (PSSPs) is a mature area, and is considered to have reached a plateau. Nonetheless, proteins are highly dynamical macromolecules, a property that could impact the PSSP methods. Indeed, in a previous study, the stability of local protein conformations was evaluated demonstrating that some regions easily changed to another type of secondary structure. The protein sequences of this dataset were used by PSSPs and their results compared to molecular dynamics to investigate their potential impact on the quality of the secondary structure prediction. Interestingly, a direct link is observed between the quality of the prediction and the stability of the assignment to the secondary structure state. The more stable a local protein conformation is, the better the prediction will be. The secondary structure assignment not taken from the crystallized structures but from the conformations observed during the dynamics slightly increase the quality of the secondary structure prediction. These results show that evaluation of PSSPs can be done differently, but also that the notion of dynamics can be included in development of PSSPs and other approaches such as de novo approaches.
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Affiliation(s)
- Alexandre G de Brevern
- Biologie Intégrée Du Globule Rouge UMR_S1134, Inserm, Université de Paris, Univ. de la Réunion, Univ. des Antilles, F-75739, Paris, France; Laboratoire D'Excellence GR-Ex, F-75739, Paris, France; Institut National de la Transfusion Sanguine (INTS), F-75739, Paris, France; IBL, F-75015, Paris, France.
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19
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Mohapatra SB, Manoj N. A conserved π-helix plays a key role in thermoadaptation of catalysis in the glycoside hydrolase family 4. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1869:140523. [PMID: 32853774 DOI: 10.1016/j.bbapap.2020.140523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 07/22/2020] [Accepted: 07/29/2020] [Indexed: 01/21/2023]
Abstract
Here, we characterize the role of a π-helix in the molecular mechanisms underlying thermoadaptation in the glycoside hydrolase family 4 (GH4). The interspersed π-helix present in a subgroup is evolutionarily related to a conserved α-helix in other orthologs by a single residue insertion/deletion event. The insertional residue, Phe407, in a hyperthermophilic α-glucuronidase, makes specific interactions across the inter-subunit interface. In order to establish the sequence-structure-stability implications of the π-helix, the wild-type and the deletion variant (Δ407) were characterized. The variant showed a significant lowering of melting temperature and optimum temperature for the highest activity. Crystal structures of the proteins show a transformation of the π-helix to a continuous α-helix in the variant, identical to that in orthologs lacking this insertion. Thermodynamic parameters were determined from stability curves representing the temperature dependence of unfolding free energy. Though the proteins display maximum stabilities at similar temperatures, a higher melting temperature in the wild-type is achieved by a combination of higher enthalpy and lower heat capacity of unfolding. Comparisons of the structural changes, and the activity and thermodynamic profiles allow us to infer that specific non-covalent interactions, and the existence of residual structure in the unfolded state, are crucial determinants of its thermostability. These features permit the enzyme to balance the preservation of structure at a higher temperature with the thermodynamic stability required for optimum catalysis.
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Affiliation(s)
- Samar Bhallabha Mohapatra
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Narayanan Manoj
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
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20
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Structural basis for the complex DNA binding behavior of the plant stem cell regulator WUSCHEL. Nat Commun 2020; 11:2223. [PMID: 32376862 PMCID: PMC7203112 DOI: 10.1038/s41467-020-16024-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 04/08/2020] [Indexed: 11/09/2022] Open
Abstract
Stem cells are one of the foundational evolutionary novelties that allowed the independent emergence of multicellularity in the plant and animal lineages. In plants, the homeodomain (HD) transcription factor WUSCHEL (WUS) is essential for the maintenance of stem cells in the shoot apical meristem. WUS has been reported to bind to diverse DNA motifs and to act as transcriptional activator and repressor. However, the mechanisms underlying this remarkable behavior have remained unclear. Here, we quantitatively delineate WUS binding to three divergent DNA motifs and resolve the relevant structural underpinnings. We show that WUS exhibits a strong binding preference for TGAA repeat sequences, while retaining the ability to weakly bind to TAAT elements. This behavior is attributable to the formation of dimers through interactions of specific residues in the HD that stabilize WUS DNA interaction. Our results provide a mechanistic basis for dissecting WUS dependent regulatory networks in plant stem cell control.
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21
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Quantum transport and utilization of free energy in protein α-helices. ADVANCES IN QUANTUM CHEMISTRY 2020. [DOI: 10.1016/bs.aiq.2020.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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22
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Zubcevic L, Lee SY. The role of π-helices in TRP channel gating. Curr Opin Struct Biol 2019; 58:314-323. [PMID: 31378426 DOI: 10.1016/j.sbi.2019.06.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 06/18/2019] [Accepted: 06/19/2019] [Indexed: 12/21/2022]
Abstract
Transient Receptor Potential (TRP) channels are a large superfamily of polymodal ion channels, which perform important roles in numerous physiological processes. The architecture of their transmembrane (TM) domains closely resembles that of voltage-gated potassium channels (KV). However, recent cryoEM and crystallographic studies of TRP channels have identified π-helices in functionally important regions, and it is increasingly recognized that they utilize a distinct mechanism of gating that relies on α-to-π secondary structure transitions. Here we review our current understanding of the role of π-helices in TRP channel function and their broader impact on different classes of ion channels.
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Affiliation(s)
- Lejla Zubcevic
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA.
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23
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Ludwiczak J, Winski A, da Silva Neto AM, Szczepaniak K, Alva V, Dunin-Horkawicz S. PiPred - a deep-learning method for prediction of π-helices in protein sequences. Sci Rep 2019; 9:6888. [PMID: 31053765 PMCID: PMC6499831 DOI: 10.1038/s41598-019-43189-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/16/2019] [Indexed: 11/17/2022] Open
Abstract
Canonical π-helices are short, relatively unstable secondary structure elements found in proteins. They comprise seven or more residues and are present in 15% of all known protein structures, often in functionally important regions such as ligand- and ion-binding sites. Given their similarity to α-helices, the prediction of π-helices is a challenging task and none of the currently available secondary structure prediction methods tackle it. Here, we present PiPred, a neural network-based tool for predicting π-helices in protein sequences. By performing a rigorous benchmark we show that PiPred can detect π-helices with a per-residue precision of 48% and sensitivity of 46%. Interestingly, some of the α-helices mispredicted by PiPred as π-helices exhibit a geometry characteristic of π-helices. Also, despite being trained only with canonical π-helices, PiPred can identify 6-residue-long α/π-bulges. These observations suggest an even higher effective precision of the method and demonstrate that π-helices, α/π-bulges, and other helical deformations may impose similar constraints on sequences. PiPred is freely accessible at: https://toolkit.tuebingen.mpg.de/#/tools/quick2d. A standalone version is available for download at: https://github.com/labstructbioinf/PiPred, where we also provide the CB6133, CB513, CASP10, and CASP11 datasets, commonly used for training and validation of secondary structure prediction methods, with correctly annotated π-helices.
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Affiliation(s)
- Jan Ludwiczak
- Laboratory of Structural Bioinformatics, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097, Warsaw, Poland.,Laboratory of Bioinformatics, Nencki Institute of Experimental Biology, Pasteura 3, 02-093, Warsaw, Poland
| | - Aleksander Winski
- Laboratory of Structural Bioinformatics, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097, Warsaw, Poland
| | - Antonio Marinho da Silva Neto
- Laboratory of Structural Bioinformatics, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097, Warsaw, Poland
| | - Krzysztof Szczepaniak
- Laboratory of Structural Bioinformatics, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097, Warsaw, Poland
| | - Vikram Alva
- Department of Protein Evolution, Max-Planck-Institute for Developmental Biology, Max-Planck-Ring 5, 72076, Tübingen, Germany
| | - Stanislaw Dunin-Horkawicz
- Laboratory of Structural Bioinformatics, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097, Warsaw, Poland.
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24
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Agip ANA, Blaza JN, Bridges HR, Viscomi C, Rawson S, Muench SP, Hirst J. Cryo-EM structures of complex I from mouse heart mitochondria in two biochemically defined states. Nat Struct Mol Biol 2018; 25:548-556. [PMID: 29915388 PMCID: PMC6054875 DOI: 10.1038/s41594-018-0073-1] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/26/2018] [Indexed: 02/02/2023]
Abstract
Complex I (NADH:ubiquinone oxidoreductase) uses the reducing potential of NADH to drive protons across the energy-transducing inner membrane and power oxidative phosphorylation in mammalian mitochondria. Recent cryo-EM analyses have produced near-complete models of all 45 subunits in the bovine, ovine and porcine complexes and have identified two states relevant to complex I in ischemia-reperfusion injury. Here, we describe the 3.3-Å structure of complex I from mouse heart mitochondria, a biomedically relevant model system, in the 'active' state. We reveal a nucleotide bound in subunit NDUFA10, a nucleoside kinase homolog, and define mechanistically critical elements in the mammalian enzyme. By comparisons with a 3.9-Å structure of the 'deactive' state and with known bacterial structures, we identify differences in helical geometry in the membrane domain that occur upon activation or that alter the positions of catalytically important charged residues. Our results demonstrate the capability of cryo-EM analyses to challenge and develop mechanistic models for mammalian complex I.
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Affiliation(s)
- Ahmed-Noor A Agip
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - James N Blaza
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Hannah R Bridges
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Carlo Viscomi
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Shaun Rawson
- School of Biomedical Sciences, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, UK
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, UK
| | - Judy Hirst
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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25
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Tikhonov DB, Zhorov BS. Conservation and variability of the pore-lining helices in P-loop channels. Channels (Austin) 2017; 11:660-672. [PMID: 29095093 DOI: 10.1080/19336950.2017.1395536] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
The family of P-loop channels, which play key roles in the cell physiology, is characterized by four membrane re-entering extracellular P-loops that connect eight transmembrane helices of the pore-forming domain. The X-ray and cryo-EM structures of the open- and closed-state channels show conserved state-dependent folding despite the sequences are very diverse. In sodium, calcium, TRPV and two-pore channels, the pore-lining helices contain conserved asparagines and may or may not include π-helix bulges. Comparison of the sequence- and 3D-alignemnts suggests that the asparagines appeared in evolution as insertions that are accommodated in two ways: by π-helix bulges, which preserve most of inter-segment contacts, or by twists of the C-terminal thirds and switch of inter-segment contacts. The two possibilities should be considered in homology modeling of ion channels and in structure-based interpretations of numerous experimental data on physiology, pathophysiology, pharmacology and toxicology of the channels.
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Affiliation(s)
- Denis B Tikhonov
- a Department of Biophysics of Synaptic Processes , Sechenov Institute of Evolutionary Physiology and Biochemistry, RAS , St. Petersburg , Russia
| | - Boris S Zhorov
- a Department of Biophysics of Synaptic Processes , Sechenov Institute of Evolutionary Physiology and Biochemistry, RAS , St. Petersburg , Russia.,b Department of Biochemistry & Biomedical Sciences , McMaster University , Hamilton , Canada
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26
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Helixconstraints and amino acid substitution in GLP-1 increase cAMP and insulin secretion but not beta-arrestin 2 signaling. Eur J Med Chem 2016; 127:703-714. [PMID: 27823886 DOI: 10.1016/j.ejmech.2016.10.044] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 12/22/2022]
Abstract
Glucagon-like peptide (GLP-1) is an endogenous hormone that induces insulin secretion from pancreatic islets and modified forms are used to treat diabetes mellitus type 2. Understanding how GLP-1 interacts with its receptor (GLP-1R) can potentially lead to more effective drugs. Modeling and NMR studies of the N-terminus of GLP-1 suggest a β-turn between residues Glu9-Phe12 and a kinked alpha helix between Val16-Gly37. N-terminal turn constraints attenuated binding affinity and activity (compounds 1-8). Lys-Asp (i, i+4) crosslinks in the middle and at the C-terminus increased alpha helicity and cAMP stimulation without much effect on binding affinity or beta-arrestin 2 recruitment (compounds 9-18). Strategic positioning of helix-inducing constraints and amino acid substitutions (Tyr16, Ala22) increased peptide helicity and produced ten-fold higher cAMP potency (compounds 19-28) over GLP-1(7-37)-NH2. The most potent cAMP activator (compound 23) was also the most potent inducer of insulin secretion.
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27
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Kumar P, Bansal M. Structural and functional analyses of PolyProline-II helices in globular proteins. J Struct Biol 2016; 196:414-425. [PMID: 27637571 DOI: 10.1016/j.jsb.2016.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/01/2016] [Accepted: 09/12/2016] [Indexed: 11/18/2022]
Abstract
PolyProline-II (PPII) helices are defined as a continuous stretch of a protein chain in which the constituent residues have backbone torsion angle (φ, ψ) values of (-75°, 145°) and take up an extended left handed helical conformation, without any intra-chain hydrogen bonds. They are found to occur quite frequently in protein structures, with their number exceeding that of π-helices, though it is considerably less than that of α-helices and β-strands. A relatively new procedure, ASSP, for the identification of regular secondary structures using Cα trace identifies 3597 PPII-helices in 3582 protein chains, solved at resolution ⩽2.0Å. Taking advantage of this significantly expanded database of PPII-helices, we have analyzed their structural and functional roles as well as determined the amino acid propensity within and around them. Though Pro residues are highly preferred, their presence is not a mandatory requirement for the formation of PPII-helices, since ∼40% PPII-helices were found to contain no Pro residues. Aromatic amino acids are avoided within this helix, while Gly, Asn and Asp residues are preferred in the proximal flanking regions. The PPII-helices range from 3 to 13 residues in length with the average twist and rise being -121.2°±9.2° and 3.0ű0.1Å respectively. A majority (∼72%) of PPII-helices were found to occur in conjunction with α-helices and β-strands, and serve as linkers as well. The analysis of various intra-helical non-bonded interactions revealed frequent presence of CH⋯O H-bonds. PPII-helices participate in maintaining the three-dimensional structure of proteins and are important constituents of binding motifs involved in various biological functions.
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Affiliation(s)
- Prasun Kumar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Manju Bansal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
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