Filter and export

Publications

What is a Publication?
458 Publications visible to you, out of a total of 458
Modeling of mechanistic effects of neurotrophin modulators

Abstract (Expand)

Neurotrophins (NTs) are growth factors that are expressed in the central and peripheral nervous systems. They are implicated in different phases of the development and maintenance of the nervous system … and they can regulate neuronal survival, development, function, plasticity, as well as neuronal apoptosis. NTs can be used as therapeutics for the treatment of neurodegenerative disorders. However, their poor pharmacokinetic properties and their invasive administration to patients renders them inefficient for use as pharmaceuticals. A solution to this can be offered by small molecule NT mimetics, which can elicit NT mechanisms through binding to NT receptors, which are transmembrane (TM) glycoproteins. The mechanism of activation of NT receptors remains elusive and thus, in this thesis, I have investigated the mechanism of action of NT receptors and mimetics through molecular modeling and molecular dynamics (MD) simulations. I modeled and simulated the glycosylated state of the full extracellular (EC) domains of Tropomyosin receptor kinases A and B (TrkA, TrkB) NT receptors, which revealed that the glycans can shield the accessible surface area of the receptors and participate in the contact area between receptor and NT. Most importantly, glycosylation promoted the extended conformations of the EC domains, which might facilitate NT binding. Then, I performed coarse-grained MD simulations to study the possible arrangements of the TM helical homodimers of TrkA and TrkB receptors in micelles. The results revealed arrangements that could correspond to the active state of the receptors, while metadynamics simulations indicated a stronger binding for the TrkA helices by 10 kJ/mol compared to TrkB. Next, I modeled the full-length structures of the TrkA and TrkB receptors in their homodimeric, glycosylated state bound to their NTs. I embedded the receptors in a realistic model of a neuronal asymmetric membrane. I verified the proper behavior of the membrane and proteins with smaller systems comprising of the TM and intracellular monomers of the receptors. These test simulations revealed interactions between positively charged residues of the kinase domain of TrkA with negatively charged lipids of the inner leaflet of the membrane. These interactions were also formed in the full-length system, and they might stabilize the two kinase domains of the receptor dimer in an orientation that promotes activation, even though the kinase domains were not activated during the simulations. Also, in the full-length systems, the EC domains approached and lay down on the neuronal membrane, while interacting with membrane lipids, such as gangliosides, which are able to activate the NT receptors. Finally, I investigated the binding of small-molecule NT mimetics to the EC and TM domains of TrkA and TrkB receptors, with molecular docking and MD simulations. While plausible poses were 8 obtained, they were not able to explain the selectivity of the compounds for the receptors and the simulations showed that binding was weak. Due to the cholesterol core of the NT mimetics, I tested the ability of the compounds to enter the cell membrane with MD simulations. The compounds were able to spontaneously penetrate the membranes, indicating that their binding site could also lie in the TM region of the receptors. However, simulations with the compounds bound or close to the TM helices in the membrane environment, showed no specific binding. Further experimental exploration of the binding mechanism of these compounds is required. Overall, this thesis sheds light on the dynamic behavior of TrkA and TrkB NT receptors in membranes and the mechanistic insights provide a basis for future studies to develop NT mimetics.

Author: Christina Athanasiou

Date Published: 30th Oct 2023

Publication Type: Doctoral Thesis

Design, synthesis and biological evaluation of antiparasitic dinitroaniline-ether phospholipid hybrids

Abstract

Not specified

Authors: Marina Roussaki, George E. Magoulas, Theano Fotopoulou, Nuno Santarem, Emile Barrias, Ina Pöhner, Sara Luelmo, Pantelis Afroudakis, Kalliopi Georgikopoulou, Paloma Tejera Nevado, Julia Eick, Eugenia Bifeld, María J. Corral, María Dolores Jiménez-Antón, Bernhard Ellinger, Maria Kuzikov, Irini Fragiadaki, Effie Scoulica, Sheraz Gul, Joachim Clos, Kyriakos C. Prousis, Juan J. Torrado, José María Alunda, Rebecca C. Wade, Wanderley de Souza, Anabela Cordeiro da Silva, Theodora Calogeropoulou

Date Published: 1st Sep 2023

Publication Type: Journal

Optimization of a Drug: Polymer Formulation Exploiting a Computational Approach based on Molecular Dynamics Simulations

Abstract

Not specified

Author: Michel Tarnow

Date Published: 22nd Aug 2023

Publication Type: Bachelor's Thesis

Molecular Dynamics Simulations of the Human Ecto-5′-Nucleotidase (h-ecto-5′-NT, CD73): Insights into Protein Flexibility and Binding Site Dynamics

Abstract

Not specified

Authors: Lucas G. Viviani, Daria B. Kokh, Rebecca C. Wade, Antonia T.-do Amaral

Date Published: 14th Aug 2023

Publication Type: Journal

PfCRT mutations conferring piperaquine resistance in falciparum malaria shape the kinetics of quinoline drug binding and transport

Abstract (Expand)

The chloroquine resistance transporter (PfCRT) confers resistance to a wide range of quinoline and quinoline-like antimalarial drugs in Plasmodium falciparum , with local drug histories driving its …rum , with local drug histories driving its evolution and, hence, the drug transport specificities. For example, the change in prescription practice from chloroquine (CQ) to piperaquine (PPQ) in Southeast Asia has resulted in PfCRT variants that carry an additional mutation, leading to PPQ resistance and, concomitantly, to CQ re-sensitization. How this additional amino acid substitution guides such opposing changes in drug susceptibility is largely unclear. Here, we show by detailed kinetic analyses that both the CQ- and the PPQ-resistance conferring PfCRT variants can bind and transport both drugs. Surprisingly, the kinetic profiles revealed subtle yet significant differences, defining a threshold for in vivo CQ and PPQ resistance. Competition kinetics, together with docking and molecular dynamics simulations, show that the PfCRT variant from the Southeast Asian P . falciparum strain Dd2 can accept simultaneously both CQ and PPQ at distinct but allosterically interacting sites. Furthermore, combining existing mutations associated with PPQ resistance created a PfCRT isoform with unprecedented non-Michaelis-Menten kinetics and superior transport efficiency for both CQ and PPQ. Our study provides additional insights into the organization of the substrate binding cavity of PfCRT and, in addition, reveals perspectives for PfCRT variants with equal transport efficiencies for both PPQ and CQ.

Authors: Guillermo M. Gomez, Giulia D’Arrigo, Cecilia P. Sanchez, Fiona Berger, Rebecca C. Wade, Michael Lanzer

Date Published: 7th Jun 2023

Publication Type: Journal

Brownian dynamics simulations of biomolecular diffusional association processes

Abstract (Expand)

Abstract Brownian dynamics (BD) is a computational method to simulate molecular diffusion processes. Although the BD method has been developed over several decades and is well established, new …d is well established, new methodological developments are improving its accuracy, widening its scope, and increasing its application. In biological applications, BD is used to investigate the diffusive behavior of molecules subject to forces due to intermolecular interactions or interactions with material surfaces. BD can be used to compute rate constants for diffusional association, generate structures of encounter complexes for molecular binding partners, and examine the transport properties of geometrically complex molecules. Often, a series of simulations is performed, for example, for different protein mutants or environmental conditions, so that the effects of the changes on diffusional properties can be estimated. While biomolecules are commonly described at atomic resolution and internal molecular motions are typically neglected, coarse‐graining and the treatment of conformational flexibility are increasingly employed. Software packages for BD simulations of biomolecules are growing in capabilities, with several new packages providing novel features that expand the range of questions that can be addressed. These advances, when used in concert with experiment or other simulation methods, such as molecular dynamics, open new opportunities for application to biochemical and biological systems. Here, we review some of the latest developments in the theory, methods, software, and applications of BD simulations to study biomolecular diffusional association processes and provide a perspective on their future use and application to outstanding challenges in biology, bioengineering, and biomedicine. This article is categorized under: Structure and Mechanism > Computational Biochemistry and Biophysics Molecular and Statistical Mechanics > Molecular Dynamics and Monte‐Carlo Methods Software > Simulation Methods

Authors: Abraham Muñiz‐Chicharro, Lane W. Votapka, Rommie E. Amaro, Rebecca C. Wade

Date Published: 1st May 2023

Publication Type: Journal

Scaling Protein–Water Interactions in the Martini 3 Coarse-Grained Force Field to Simulate Transmembrane Helix Dimers in Different Lipid Environments

Abstract

Not specified

Authors: Ainara Claveras Cabezudo, Christina Athanasiou, Alexandros Tsengenes, Rebecca C. Wade

Date Published: 11th Apr 2023

Publication Type: Journal

Powered by
 (v.1.16.0)
About HITS Publication SEEK | About HITS-Publication-SEEK | Funding and Programmes | Credits
Copyright © 2008 - 2024 The University of Manchester and HITS gGmbH