scholarly journals Molecular Modeling of the M3 Acetylcholine Muscarinic Receptor and Its Binding Site

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Marlet Martinez-Archundia ◽  
Arnau Cordomi ◽  
Pere Garriga ◽  
Juan J. Perez
Keyword(s):  
Binding Site ◽  
Lipid Bilayer ◽  
Muscarinic Acetylcholine Receptor ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Crystallographic Structure ◽  
Bovine Rhodopsin ◽  
Site Mutagenesis ◽  
Dynamics Simulations ◽  
Mutagenesis Study

The present study reports the results of a combined computational and site mutagenesis study designed to provide new insights into the orthosteric binding site of the human M3 muscarinic acetylcholine receptor. For this purpose a three-dimensional structure of the receptor at atomic resolution was built by homology modeling, using the crystallographic structure of bovine rhodopsin as a template. Then, the antagonist N-methylscopolamine was docked in the model and subsequently embedded in a lipid bilayer for its refinement using molecular dynamics simulations. Two different lipid bilayer compositions were studied: one component palmitoyl-oleyl phosphatidylcholine (POPC) and two-component palmitoyl-oleyl phosphatidylcholine/palmitoyl-oleyl phosphatidylserine (POPC-POPS). Analysis of the results suggested that residues F222 and T235 may contribute to the ligand-receptor recognition. Accordingly, alanine mutants at positions 222 and 235 were constructed, expressed, and their binding properties determined. The results confirmed the role of these residues in modulating the binding affinity of the ligand.

scholarly journals Online biophysical predictions for SARS-CoV-2 proteins

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Luciano Kagami ◽  
Joel Roca-Martínez ◽  
Jose Gavaldá-García ◽  
Pathmanaban Ramasamy ◽  
K. Anton Feenstra ◽  
...  
Keyword(s):  
Protein Sequence ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Static Structure ◽  
Homologous Proteins ◽  
Structure Based Drug Design ◽  
Protein Protein Interaction ◽  
Link Type ◽  
Dynamics Simulations ◽  
Β Sheet

Abstract Background The SARS-CoV-2 virus, the causative agent of COVID-19, consists of an assembly of proteins that determine its infectious and immunological behavior, as well as its response to therapeutics. Major structural biology efforts on these proteins have already provided essential insights into the mode of action of the virus, as well as avenues for structure-based drug design. However, not all of the SARS-CoV-2 proteins, or regions thereof, have a well-defined three-dimensional structure, and as such might exhibit ambiguous, dynamic behaviour that is not evident from static structure representations, nor from molecular dynamics simulations using these structures. Main We present a website (https://bio2byte.be/sars2/) that provides protein sequence-based predictions of the backbone and side-chain dynamics and conformational propensities of these proteins, as well as derived early folding, disorder, β-sheet aggregation, protein-protein interaction and epitope propensities. These predictions attempt to capture the inherent biophysical propensities encoded in the sequence, rather than context-dependent behaviour such as the final folded state. In addition, we provide the biophysical variation that is observed in homologous proteins, which gives an indication of the limits of their functionally relevant biophysical behaviour. Conclusion The https://bio2byte.be/sars2/ website provides a range of protein sequence-based predictions for 27 SARS-CoV-2 proteins, enabling researchers to form hypotheses about their possible functional modes of action.

scholarly journals The Three-dimensional Structure of Bovine Rhodopsin Determined by Electron Cryomicroscopy

2003 ◽  
Vol 278 (50) ◽  
pp. 50217-50225 ◽  
Author(s):  
Angelika Krebs ◽  
Patricia C. Edwards ◽  
Claudio Villa ◽  
Jade Li ◽  
Gebhard F. X. Schertler
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Electron Cryomicroscopy ◽  
Three Dimensional Structure ◽  
Bovine Rhodopsin

THE THREE-DIMENSIONAL STRUCTURE OF THE ANTIGEN BINDING SITE OF McPC 603 PROTEIN

1974 ◽  
pp. 7-14 ◽  
Author(s):  
E.A. Padlan ◽  
D.M. Segal ◽  
G.H. Cohen ◽  
D.R. Davies ◽  
S. Rudikoff ◽  
...  
Keyword(s):  
Binding Site ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Antigen Binding ◽  
Antigen Binding Site ◽  
Three Dimensional Structure

scholarly journals New insights on human IRE1 tetramer structures based on molecular modeling

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Antonio Carlesso ◽  
Johanna Hörberg ◽  
Anna Reymer ◽  
Leif A. Eriksson
Keyword(s):  
Conformational Changes ◽  
Three Dimensional ◽  
Protein Docking ◽  
Activation Mechanism ◽  
Crystallographic Structure ◽  
Face To Face ◽  
Unfolded Protein ◽  
Dynamics Simulations ◽  
The Unfolded Protein Response ◽  
Protein Response

Abstract Inositol-Requiring Enzyme 1α (IRE1α; hereafter IRE1) is a transmembrane kinase/ribonuclease protein related with the unfolded protein response (UPR) signaling. Experimental evidence suggests that IRE1 forms several three dimensional (3D) structural variants: dimers, tetramers and higher order oligomers, where each structural variant can contain different IRE1 conformers in different arrangements. For example, studies have shown that two sets of IRE1 dimers exist; a face-to-face dimer and a back-to-back dimer, with the latter considered the important unit for UPR signaling propagation. However, the structural configuration and mechanistic details of the biologically important IRE1 tetramers are limited. Here, we combine protein–protein docking with molecular dynamics simulations to derive human IRE1 tetramer models and identify a molecular mechanism of IRE1 activation. To validate the derived models of the human IRE1 tetramer, we compare the dynamic behavior of the models with the yeast IRE1 tetramer crystallographic structure. We show that IRE1 tetramer conformational changes could be linked to the initiation of the unconventional splicing of mRNA encoding X-box binding protein-1 (XBP1), which allows for the expression of the transcription factor XBP1s (XBP1 spliced). The derived IRE1 tetrameric models bring new mechanistic insights about the IRE1 molecular activation mechanism by describing the IRE1 tetramers as active protagonists accommodating the XBP1 substrate.

Structure of the Calcium Pump from Sarcoplasmic Reticulum at 8 Å Resolution: Architecture of the Transmembrane Helices and Localization of the Binding Site for Thapsigargin

1998 ◽  
Vol 4 (S2) ◽  
pp. 462-463
Author(s):  
P. Zhang ◽  
C. Toyoshima ◽  
K. Yonekura ◽  
G. Inesi ◽  
M. Green ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Transmembrane Domain ◽  
Three Dimensional ◽  
Specific Inhibitor ◽  
Large Family ◽  
Calcium Pump ◽  
Dimensional Structure ◽  
Transmembrane Helices ◽  
Site Mutagenesis ◽  
P Type

The calcium pump (Ca2+-ATPase) from sarcoplasmic reticulum (SR) is a prominent member of the large family of ATP-dependent cation pumps, which include Na+ /K+-ATPase, H+/K+-ATPase from the stomach, H+-ATPase from yeast and Neurospora, and various detoxifying pumps for Cd+, Cu+ and other metals. In muscle, calcium is stored inside the SR and contraction is initiated by regulated release through specific calcium channels; Ca2+ -ATPase is responsible for relaxation by pumping calcium back into the SR lumen. Many techniques (chemical modification, site mutagenesis, reaction kinetics) have been used to correlate Ca2+-ATPase sequence with function, but no high resolution three-dimensional structure of Ca2+-ATPase, or any P-type pump, has yet been determined. In the current work, we have determined the structure from helical crystals at 8 A resolution and thus revealed the alpha-helical architecture of the transmembrane domain. In addition, a specific inhibitor of Ca2+-ATPase, thapsigargin, was used to promote crystallization and we have characterized the structural consequences of its inhibition.

scholarly journals Oligomeric Structure of Colicin Ia Channel in Lipid Bilayer Membranes

2009 ◽  
Vol 284 (24) ◽  
pp. 16126-16134 ◽  
Author(s):  
Sarah L. Greig ◽  
Mazdak Radjainia ◽  
Alok K. Mitra
Keyword(s):  
Lipid Bilayer ◽  
Large Scale ◽  
Three Dimensional ◽  
Velocity Sedimentation ◽  
Dimensional Structure ◽  
Lipid Bilayer Membranes ◽  
Outer Membrane Receptor ◽  
Bilayer Membranes ◽  
Three Dimensional Structure ◽  
Colicin Ia

Colicin Ia is a soluble, harpoon-shaped bacteriocin which translocates across the periplasmic space of sensitive Escherichia coli cell by parasitizing an outer membrane receptor and forms voltage-gated ion channels in the inner membrane. This process leads to cell death, which has been thought to be caused by a single colicin Ia molecule. To directly visualize the three-dimensional structure of the channel, we generated two-dimensional crystals of colicin Ia inserted in lipid-bilayer membranes and determined a ∼17 three-dimensional model by electron crystallography. Supported by velocity sedimentation, chemical cross-linking and single-particle image analysis, the three-dimensional structure is a crown-shaped oligomer enclosing a ∼35 Å-wide extrabilayer vestibule. Our study suggests that lipid insertion instigates a global conformational change in colicin Ia and that more than one molecule participates in the channel architecture with the vestibule, possibly facilitating the known large scale peptide translocation upon channel opening.

scholarly journals Single particle cryo-EM structure of the outer hair cell motor protein prestin

2021 ◽  
Author(s):  
Carmen BUtan ◽  
Qiang Song ◽  
Jun-ping Bai ◽  
Winston Tan ◽  
Dhasakumar S Navaratnam ◽  
...  
Keyword(s):  
Hair Cell ◽  
Binding Site ◽  
Outer Hair Cell ◽  
Three Dimensional ◽  
Structural Features ◽  
Meriones Unguiculatus ◽  
Dimensional Structure ◽  
Transmembrane Segments ◽  
Anion Transporter ◽  
Mechanistic Basis

The mammalian outer hair cell (OHC) protein prestin (Slc26a5), a member of the solute carrier 26 (Slc26) family of membrane proteins, differs from other members of the family owing to its unique piezoelectric-like property that drives OHC electromotility. Prestin is required by OHCs for cochlear amplification, a process that enhances mammalian hearing. Despite substantial biophysical characterization, the mechanistic basis for the prestins electro-mechanical behavior is not fully understood. To gain insight into such behavior, we have used cryo-electron microscopy at subnanometer resolution (overall resolution of 4.0 Å) to investigate the three-dimensional structure of prestin from gerbil (Meriones unguiculatus). Our studies show that prestin dimerizes with a 3D architecture strikingly similar to the dimeric conformation observed in the Slc26a9 anion transporter in an inside open/intermediate state, which we infer, based on patch clamp recordings, to reflect the contracted state of prestin. The structure shows two well separated transmembrane (TM) subunits and two cytoplasmic sulfate transporter and anti-sigma factor antagonist (STAS) domains forming a swapped dimer. The dimerization interface is defined by interactions between the domain-swapped STAS dimer and the transmembrane domains of the opposing half unit, further strengthened by an antiparallel beta strand at its N terminus. The structure also shows that each one of its two transmembrane subunits consists of 14 transmembrane segments organized in two inverted 7-segment repeats with a topology that was first observed in the structure of the bacterial symporter UraA (Lu F, et al., Nature 472, 2011). Finally, the solved anion binding site structural features of prestin are quite similar to that of SLC26a9 and other family members. Despite this similarity, we find that SLC26a9 lacks the characteristic displacement currents (or NonLinear Capacitance(NLC)) found with prestin, and we show that mutation of prestins Cl- binding site removes salicylate competition with anions in the face of normal NLC, thus refuting the yet accepted extrinsic voltage sensor hypothesis and any associated transport-like requirements for voltage-driven electromotility.

scholarly journals Prediction of fluorophore brightness in designed mini fluorescence activating proteins

2021 ◽  
Author(s):  
Emma R. Hostetter ◽  
Jeffrey R. Keyes ◽  
Ivy Poon ◽  
Justin P. Nguyen ◽  
Jacob Nite ◽  
...  
Keyword(s):  
Protein Function ◽  
De Novo ◽  
Energy Landscape ◽  
Three Dimensional ◽  
Computational Design ◽  
Dimensional Structure ◽  
Bond Rotation ◽  
Beta Barrel ◽  
Angle Rotation ◽  
Dynamics Simulations

The de novo computational design of proteins with predefined three-dimensional structure is becoming much more routine due to advancements both in force fields and algorithms. However, creating designs with functions beyond folding is more challenging. In that regard, the recent design of small beta barrel proteins that activate the fluorescence of an exogenous small molecule chromophore (DFHBI) is noteworthy. These proteins, termed mini Fluorescence Activating Proteins (mFAPs), have been shown increase the brightness of the chromophore more than 100-fold upon binding to the designed ligand pocket. The design process created a large library of variants with different brightness levels but gave no rational explanation for why one variant was brighter than another. Here we use quantum mechanics and molecular dynamics simulations to investigate how molecular flexibility in the ground and excited states influences brightness. We show that the ability of the protein to resist dihedral angle rotation of the chromophore is critical for predicting brightness. Our simulations suggest that the mFAP/DFHBI complex has a rough energy landscape, requiring extensive ground-state sampling to achieve converged predictions of excited-state kinetics. While computationally demanding, this roughness suggests that mFAP protein function can be enhanced by reshaping the energy landscape towards states that better resist DFHBI bond rotation.

scholarly journals BiRDS - Binding Residue Detection from Protein Sequences using Deep ResNets

2021 ◽  
Author(s):  
Vineeth Chelur ◽  
U. Deva Priyakumar
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Tertiary Structure ◽  
Solvent Accessibility ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Relative Solvent Accessibility ◽  
Single Chain ◽  
Sequence Alignments ◽  
Multiple Sequence

Protein-drug interactions play important roles in many biological processes and therapeutics. Prediction of the active binding site of a protein helps discover and optimise these interactions leading to the design of better ligand molecules. The tertiary structure of a protein determines the binding sites available to the drug molecule. A quick and accurate prediction of the binding site from sequence alone without utilising the three-dimensional structure is challenging. Deep Learning has been used in a variety of biochemical tasks and has been hugely successful. In this paper, a Residual Neural Network (leveraging skip connections) is implemented to predict a protein's most active binding site. An Annotated Database of Druggable Binding Sites from the Protein DataBank, sc-PDB, is used for training the network. Features extracted from the Multiple Sequence Alignments (MSAs) of the protein generated using DeepMSA, such as Position-Specific Scoring Matrix (PSSM), Secondary Structure (SS3), and Relative Solvent Accessibility (RSA), are provided as input to the network. A weighted binary cross-entropy loss function is used to counter the substantial imbalance in the two classes of binding and non-binding residues. The network performs very well on single-chain proteins, providing a pocket that has good interactions with a ligand.

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