scholarly journals A coarse-grained xDLVO model for colloidal protein-protein interactions

2021 ◽  
Author(s):  
Srdjan Pusara ◽  
Wolfgang Wenzel ◽  
Marjan Krstić ◽  
Mariana Kozlowska
Keyword(s):  
Protein Interactions ◽  
Coarse Grained ◽  
Protein Protein Interactions ◽  
Biotechnological Processes ◽  
Xdlvo Model

Colloidal protein-protein interactions (PPIs) of attractive and repulsive nature modulate the solubility of proteins, their aggregation, precipitation and crystallization. Such interactions are very important for many biotechnological processes, but are...

scholarly journals Expansion of Intrinsically Disordered Proteins Increases the Range of Stability of Liquid–Liquid Phase Separation

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4705
Author(s):  
Adiran Garaizar ◽  
Ignacio Sanchez-Burgos ◽  
Rosana Collepardo-Guevara ◽  
Jorge R. Espinosa
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Protein Interactions ◽  
Conformational Dynamics ◽  
Liquid Phase Separation ◽  
Phase Behaviour ◽  
Coarse Grained ◽  
Protein Protein Interactions ◽  
Intrinsically Disordered ◽  
Liquid Liquid Phase Separation

Proteins containing intrinsically disordered regions (IDRs) are ubiquitous within biomolecular condensates, which are liquid-like compartments within cells formed through liquid–liquid phase separation (LLPS). The sequence of amino acids of a protein encodes its phase behaviour, not only by establishing the patterning and chemical nature (e.g., hydrophobic, polar, charged) of the various binding sites that facilitate multivalent interactions, but also by dictating the protein conformational dynamics. Besides behaving as random coils, IDRs can exhibit a wide-range of structural behaviours, including conformational switching, where they transition between alternate conformational ensembles. Using Molecular Dynamics simulations of a minimal coarse-grained model for IDRs, we show that the role of protein conformation has a non-trivial effect in the liquid–liquid phase behaviour of IDRs. When an IDR transitions to a conformational ensemble enriched in disordered extended states, LLPS is enhanced. In contrast, IDRs that switch to ensembles that preferentially sample more compact and structured states show inhibited LLPS. This occurs because extended and disordered protein conformations facilitate LLPS-stabilising multivalent protein–protein interactions by reducing steric hindrance; thereby, such conformations maximize the molecular connectivity of the condensed liquid network. Extended protein configurations promote phase separation regardless of whether LLPS is driven by homotypic and/or heterotypic protein–protein interactions. This study sheds light on the link between the dynamic conformational plasticity of IDRs and their liquid–liquid phase behaviour.

scholarly journals Kinetic frustration by limited bond availability controls the LAT protein condensation phase transition on membranes

2021 ◽  
Author(s):  
Simou Sun ◽  
Trevor GrandPre ◽  
David T. Limmer ◽  
Jay T. Groves
Keyword(s):  
Phase Transition ◽  
T Cell Activation ◽  
Protein Interactions ◽  
Cell Activation ◽  
Coarse Grained ◽  
Structural Basis ◽  
Protein Protein Interactions ◽  
Kinetic Measurements ◽  
Coarse Grained Model ◽  
Intrinsically Disordered

AbstractLAT is a membrane-linked scaffold protein that undergoes a phase transition to form a two-dimensional protein condensate on the membrane during T cell activation. Governed by tyrosine phosphorylation, LAT recruits various proteins that ultimately enable condensation through a percolation network of discrete and selective protein-protein interactions. Here we describe detailed kinetic measurements of the phase transition, along with coarse-grained model simulations, that reveal LAT condensation is kinetically frustrated by the availability of bonds to form the network. Unlike typical miscibility transitions in which compact domains may coexist at equilibrium, the LAT condensates are dynamically arrested in extended states, kinetically trapped out of equilibrium. Modeling identifies the structural basis for this kinetic arrest as the formation of spindle arrangements, favored by limited multivalent binding interactions along the flexible, intrinsically disordered LAT protein. These results reveal how local factors controlling the kinetics of LAT condensation enable formation of different, stable condensates, which may ultimately coexist within the cell.

scholarly journals Regulation of ryanodine receptor RyR2 by protein-protein interactions: prediction of a PKA binding site on the N-terminal domain of RyR2 and its relation to disease causing mutations

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 29 ◽  
Author(s):  
Belinda Nazan Walpoth ◽  
Burak Erman
Keyword(s):  
Binding Site ◽  
Protein Interactions ◽  
Elastic Net ◽  
Coarse Grained ◽  
Protein Protein Interactions ◽  
Analysis Model ◽  
Terminal Domain ◽  
Binding Partners ◽  
Atomistic Calculations ◽  
And Function

Protein-protein interactions are the key processes responsible for signaling and function in complex networks. Determining the correct binding partners and predicting the ligand binding sites in the absence of experimental data require predictive models. Hybrid models that combine quantitative atomistic calculations with statistical thermodynamics formulations are valuable tools for bioinformatics predictions. We present a hybrid prediction and analysis model for determining putative binding partners and interpreting the resulting correlations in the yet functionally uncharacterized interactions of the ryanodine RyR2 N-terminal domain. Using extensive docking calculations and libraries of hexameric peptides generated from regulator proteins of the RyR2 channel, we show that the residues 318-323 of protein kinase A, PKA, have a very high affinity for the N-terminal of RyR2. Using a coarse grained Elastic Net Model, we show that the binding site lies at the end of a pathway of evolutionarily conserved residues in RyR2. The two disease causing mutations are also on this path. The program for the prediction of the energetically responsive residues by the Elastic Net Model is freely available on request from the corresponding author.

scholarly journals Liquid network connectivity regulates the stability and composition of biomolecular condensates with many components

2020 ◽  
Vol 117 (24) ◽  
pp. 13238-13247 ◽  
Author(s):  
Jorge R. Espinosa ◽  
Jerelle A. Joseph ◽  
Ignacio Sanchez-Burgos ◽  
Adiran Garaizar ◽  
Daan Frenkel ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Critical Points ◽  
Network Connectivity ◽  
Coarse Grained ◽  
Physical Parameters ◽  
Protein Protein Interactions ◽  
Coarse Grained Model ◽  
Bond Network ◽  
The Stability ◽  
Liquid Liquid Phase Separation

One of the key mechanisms used by cells to control the spatiotemporal organization of their many components is the formation and dissolution of biomolecular condensates through liquid–liquid phase separation (LLPS). Using a minimal coarse-grained model that allows us to simulate thousands of interacting multivalent proteins, we investigate the physical parameters dictating the stability and composition of multicomponent biomolecular condensates. We demonstrate that the molecular connectivity of the condensed-liquid network—i.e., the number of weak attractive protein–protein interactions per unit of volume—determines the stability (e.g., in temperature, pH, salt concentration) of multicomponent condensates, where stability is positively correlated with connectivity. While the connectivity of scaffolds (biomolecules essential for LLPS) dominates the phase landscape, introduction of clients (species recruited via scaffold–client interactions) fine-tunes it by transforming the scaffold–scaffold bond network. Whereas low-valency clients that compete for scaffold–scaffold binding sites decrease connectivity and stability, those that bind to alternate scaffold sites not required for LLPS or that have higher-than-scaffold valencies form additional scaffold–client–scaffold bridges increasing stability. Proteins that establish more connections (via increased valencies, promiscuous binding, and topologies that enable multivalent interactions) support the stability of and are enriched within multicomponent condensates. Importantly, proteins that increase the connectivity of multicomponent condensates have higher critical points as pure systems or, if pure LLPS is unfeasible, as binary scaffold–client mixtures. Hence, critical points of accessible systems (i.e., with just a few components) might serve as a unified thermodynamic parameter to predict the composition of multicomponent condensates.

PACSAB: Coarse-Grained Force Field for the Study of Protein–Protein Interactions and Conformational Sampling in Multiprotein Systems

2015 ◽  
Vol 11 (12) ◽  
pp. 5929-5938 ◽  
Author(s):  
Agustí Emperador ◽  
Pedro Sfriso ◽  
Marcos Ariel Villarreal ◽  
Josep Lluis Gelpí ◽  
Modesto Orozco
Keyword(s):  
Force Field ◽  
Protein Interactions ◽  
Coarse Grained ◽  
Conformational Sampling ◽  
Protein Protein Interactions
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