Search results for "folding"
showing 10 items of 330 documents
Polar/Ionizable Residues in Transmembrane Segments: Effects on Helix-Helix Packing
2012
The vast majority of membrane proteins are anchored to biological membranes through hydrophobic alpha-helices. Sequence analysis of high-resolution membrane protein structures show that ionizable amino acid residues are present in transmembrane (TM) helices, often with a functional and/or structural role. Here, using as scaffold the hydrophobic TM domain of the model membrane protein glycophorin A (GpA), we address the consequences of replacing specific residues by ionizable amino acids on TM helix insertion and packing, both in detergent micelles and in biological membranes. Our findings demonstrate that ionizable residues are stably inserted in hydrophobic environments, and tolerated in t…
Investigation of Phosphorylation-Induced Folding of an Intrinsically Disordered Protein by Coarse-Grained Molecular Dynamics
2021
Apart from being the most common mechanism of regulating protein function and transmitting signals throughout the cell, phosphorylation has an ability to induce disorder-to-order transition in an intrinsically disordered protein. In particular, it was shown that folding of the intrinsically disordered protein, eIF4E-binding protein isoform 2 (4E-BP2), can be induced by multisite phosphorylation. Here, the principles that govern the folding of phosphorylated 4E-BP2 (pT37pT46 4E-BP2(18–62)) are investigated by analyzing canonical and replica exchange molecular dynamics trajectories, generated with the coarse-grained united-residue force field, in terms of local and global motions and the time…
Human apolipoprotein A-I natural variants: molecular mechanisms underlying amyloidogenic propensity
2012
Human apolipoprotein A-I (apoA-I)-derived amyloidosis can present with either wild-type (Wt) protein deposits in atherosclerotic plaques or as a hereditary form in which apoA-I variants deposit causing multiple organ failure. More than 15 single amino acid replacement amyloidogenic apoA-I variants have been described, but the molecular mechanisms involved in amyloid-associated pathology remain largely unknown. Here, we have investigated by fluorescence and biochemical approaches the stabilities and propensities to aggregate of two disease-associated apoA-I variants, apoA-IGly26Arg, associated with polyneuropathy and kidney dysfunction, and apoA-ILys107-0, implicated in amyloidosis in severe…
Strategies for the production of difficult-to-express full-length eukaryotic proteins using microbial cell factories : production of human alpha-gala…
2015
This work was supported by ERANET-IB08-007 project from the European Union and its linked national project EUI2008- 03610 to AV. We also appreciate the support from EME2007-08 to NFM from Universitat Autonoma de Barcelona, from Antartide 2010 to MLT and EP, from MIUR Azioni Integrate Italia-Spagna 2010 Prot. IT10LECLM9 to MLT, from MINECO (IT2009-0021) to AV and LT, from AGAUR (2009SGR-108) to AV. AV is also supported by The Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN, Spain), an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Car…
Mechanical unfolding pathway of a model β-peptide foldamer.
2015
Foldamers constructed from oligomers of β-peptides form stable secondary helix structures already for small chain lengths, which makes them ideal candidates for the investigation of the (un)folding of polypeptides. Here, the results of molecular simulations of the mechanical unfolding of a β-heptapeptide in methanol solvent revealing the detailed unfolding pathway are reported. The unfolding process is shown to proceed via a stable intermediate even for such a small system. This result is arrived at performing non-equilibrium force ramp simulations employing different pulling velocities and also using standard calculations of the potential of mean force, i.e., the free energy as a function …
Analytical and Numerical Investigation of 3D Multilayer Detachment Folding
2013
Multilayer detachment folding, in which a sequence of sedimentary layers is compressed above a weaker salt layer, is a common mode of deformation in thin-skinned fold-and-thrust belts. Here, we investigate the dynamics of multilayer detachment folding with three different viscosities: lower detachment or salt layer, overlying weak layers and competent layers. A semi-analytical solution, based on thick plate analysis of multilayer systems, is used to create mechanical phase diagrams of folding dominant wavelength and growth rate as a function of material parameters. The validity of the phase diagrams is tested and confirmed beyond the nucleation stages of folding by performing several 2D and…
Modeling of the Halloysite Spiral Nanotube
2015
A computational SCC-DFTB investigation dealing with the structure of hydrated and anhydrous halloysite nanotubes with a spiral geometry is reported. The peculiar characteristics of these systems are described in terms of tetrahedral and octahedral distortions, of hydrogen bonds geometries involving water molecules and the surfaces in the hydrated nanotube, and of the interlayer interactions in the anhydrous one. When the properties of the spiral nanotube are compared with those of the kaolinite sheet, a certain degree of intrinsic disorder in the halloysite systems is revealed, due to the intrinsic nature of the spiral folding. This is particularly evident in the hydrogen bonds network occu…
Solvent-induced free energy landscape and solute-solvent dynamic coupling in a multielement solute
1999
AbstractMolecular dynamics simulations using a simple multielement model solute with internal degrees of freedom and accounting for solvent-induced interactions to all orders in explicit water are reported. The potential energy landscape of the solute is flat in vacuo. However, the sole untruncated solvent-induced interactions between apolar (hydrophobic) and charged elements generate a rich landscape of potential of mean force exhibiting typical features of protein landscapes. Despite the simplicity of our solute, the depth of minima in this landscape is not far in size from free energies that stabilize protein conformations. Dynamical coupling between configurational switching of the syst…
Effective approach for calculations of absolute stability of proteins using focused dielectric constants
2009
The ability to predict the absolute stability of proteins based on their corresponding sequence and structure is a problem of great fundamental and practical importance. In this work, we report an extensive, refinement and validation of our recent approach (Roca et al., FEBS Lett 2007;581:2065-2071) for predicting absolute values of protein stability DeltaG(fold). This approach employs the semimacroscopic protein dipole Langevin dipole method in its linear response approximation version (PDLD/S-LRA) while using the best fitted values of the dielectric constants epsilon'(p) and epsilon'(eff) for the self energy and charge-charge interactions, respectively. The method is validated on a divers…
New set of 2D/3D thermodynamic indices for proteins. A formalism based on "Molten Globule" theory
2010
Abstract We define eight new macromolecular indices, and several related descriptors for proteins. The coarse grained methodology used for its deduction ensures its fast execution and becomes a powerful potential tool to explore large databases of protein structures. The indices are intended for stability studies, predicting Φ -values, predicting folding rate constants, protein QSAR/QSPR as well as protein alignment studies. Also, these indices could be used as scoring function in protein-protein docking or 3D protein structure prediction algorithms and any others applications which need a numerical code for proteins and/or residues from 2D or 3D format.