Characterizing early drug resistance-related events using geometric ensembles from HIV protease dynamics:

The use of antiretrovirals (ARVs) has drastically improved the life quality and expectancy of HIV patients since their introduction in health care. Several millions are still afflicted worldwide by HIV and ARV resistance is a constant concern for both healthcare practitioners and patients, as while treatment options are finite, the virus constantly adapts via complex mutation patterns to select for resistant strains under the pressure of drug treatment. The HIV protease is a crucial enzyme for viral maturation and has been a game changing drug target since the first application. Due to similarities in protease inhibitor designs, drug cross-resistance is not uncommon across ARVs of the same class

Selective Preservation of Bone Marrow Mature Recirculating but Not Marginal Zone B Cells in Murine Models of Chronic Inflammation

Inflammation promotes granulopoiesis over B lymphopoiesis in the bone marrow (BM). We studied B cell homeostasis in two murine models of T cell mediated chronic inflammation, namely calreticulin-deficient fetal liver chimeras (FLC), which develop severe blepharitis and alopecia due to T cell hyper responsiveness, and inflammatory bowel disease (IBD) caused by injection of CD4+ naïve T cells into lymphopenic mice. We show herein that despite the severe depletion of B cell progenitors during chronic, peripheral T cell-mediated inflammation, the population of BM mature recirculating B cells is unaffected. These B cells are poised to differentiate to plasma cells in response to blood borne pathogens, in an analogous fashion to non-recirculating marginal zone (MZ) B cells in the spleen. MZ B cells nevertheless differentiate more efficiently to plasma cells upon polyclonal stimulation by Toll-like receptor (TLR) ligands, and are depleted during chronic T cell mediated inflammation in vivo. The preservation of mature B cells in the BM is associated with increased concentration of macrophage migration inhibitory factor (MIF) in serum and BM plasma. MIF produced by perivascular dendritic cells (DC) in the BM provides a crucial survival signal for recirculating B cells, and mice treated with a MIF inhibitor during inflammation showed significantly reduced mature B cells in the BM. These data indicate that MIF secretion by perivascular DC may promote the survival of the recirculating B cell pool to ensure responsiveness to blood borne microbes despite loss of the MZ B cell pool that accompanies depressed lymphopoiesis during inflammation

Parameterization of a coarse-grained model of cholesterol with point-dipole electrostatics

© 2018, Springer Nature Switzerland AG. We present a new coarse-grained (CG) model of cholesterol (CHOL) for the electrostatic-based ELBA force field. A distinguishing feature of our CHOL model is that the electrostatics is modeled by an explicit point dipole which interacts through an ideal vacuum permittivity. The CHOL model parameters were optimized in a systematic fashion, reproducing the electrostatic and nonpolar partitioning free energies of CHOL in lipid/water mixtures predicted by full-detailed atomistic molecular dynamics simulations. The CHOL model has been validated by comparison to structural, dynamic and thermodynamic properties with experimental and atomistic simulation reference data. The simulation of binary DPPC/cholesterol mixtures covering the relevant biological content of CHOL in mammalian membranes is shown to correctly predict the main lipid behavior as observed experimentally

Allostery in membrane proteins

Membrane proteins are an integral part of signal transduction. To signal, membrane proteins must interact with a variety of lipid species, effectors, and other proteins in the biological membrane leading to an immense number of possible interactions. Despite this inherent complexity, accurate control of signaling must take place. By allowing proteins to adopt a multiplicity of conformations in a process known as allostery, nature is able to transmit a signal from one protein site to another distal, functional site, allowing for modulation of protein properties and regulation of activity. In recent years, an increasing number of reports have pointed to common mechanisms governing the allosteric modulation of membrane proteins, including conformational selection, oligomerization, and the modulation of allosteric sites. In this report, we summarize recent advances in membrane protein allostery. © 202

Rational design of allosteric modulators: Challenges and successes

Recent advances in structural biology and computational techniques have revealed allosteric mechanisms for an abundance of targets leading to the establishment of rational design of allosteric modulators as a new avenue for drug discovery. Considering that allostery is an intrinsic property of the protein conformational ensemble, allosteric drug design has the potential to develop into an innovative approach to modulate the dysregulation of therapeutic targets that are considered to be undruggable at their orthosteric site, explore strategic design opportunities to tackle new chemical space, or develop mutant-specific therapies to target mutations occurring far from the enzyme active site. Traditionally, allosteric drug discovery has been performed through high-throughput screening or through serendipitous discoveries; however, recent developments in structure-based and ligand-based methods have led to exciting advancements of designing bioactive allosteric ligands rationally. In this review article, we highlight the advantages and disadvantages of allosteric modulators and present structure-based and ligand-based drug design methodologies for the identification of allosteric binding sites and allosteric modulators. We also illustrate representative studies for the design allosteric modulators for proteins belonging to a wide range of protein families, also considering irreversible binding with covalent allosteric modulators. Additionally, we analyze challenges and successes in the rational design of allosteric inhibitors and activators. Finally, we present the future of rational allosteric ligand design with newly built computational tools that we expect to be applied in future studies, concluding to theoretical and practical guidelines for allosteric ligand design strategies and identify knowledge gaps that need to be addressed to improve efficiency in allosteric drug design. This article is categorized under: Structure and Mechanism > Computational Biochemistry and Biophysics Structure and Mechanism > Molecular Structures. © 2021 Wiley Periodicals LLC

Free energy calculations reveal the origin of binding preference for aminoadamantane blockers of influenza A/M2TM pore

Aminoadamantane derivatives, such as amantadine and rimantadine, have been reported to block the M2 membrane protein of influenza A virus (A/M2TM), but their use has been discontinued due to reported resistance in humans. Understanding the mechanism of action of amantadine derivatives could assist the development of novel potent inhibitors that overcome A/M2TM resistance. Here, we use Free Energy Perturbation calculations coupled with Molecular Dynamics simulations (FEP/MD) to rationalize the thermodynamic origin of binding preference of several aminoadamantane derivatives inside the A/M2TM pore. Our results demonstrate that apart from crucial protein-ligand intermolecular interactions, the flexibility of the protein, the water network around the ligand, and the desolvation free energy penalty to transfer the ligand from the aqueous environment to the transmembrane region are key elements for the binding preference of these compounds and thus for lead optimization. The high correlation of the FEP/MD results with available experimental data (R 2 = 0.85) demonstrates that this methodology holds predictive value and can be used to guide the optimization of drug candidates binding to membrane proteins. © 2012 American Chemical Society

NanoCrystal: A Web-Based Crystallographic Tool for the Construction of Nanoparticles Based on Their Crystal Habit

Modeling of nanoparticles is an essential first step to assess their capacities for different uses such as energy storage and drug delivery. However, creating an initial starting conformation for modeling and simulation is tedious because every crystalline material grows with a different crystal habit. In this application note, we describe NanoCrystal, a novel web-based crystallographic tool that creates nanoparticle models from any crystal structure guided by their preferred equilibrium shape under standard conditions according to the Wulff morphology (crystal habit). Users can upload a cif file, define the Miller indices and their corresponding minimum surface energies according to the Wulff construction of a particular crystal, and specify the size of the nanocrystal. As a result, the nanoparticle is constructed and visualized, and the coordinates of the atoms are output to the user. NanoCrystal can be accessed at http://nanocrystal.vi-seem.edu/. © 2018 American Chemical Society