scholarly journals Intrinsically disordered proteins: controlled chaos or random walk

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
T.C. Howton ◽  
Yingqian Ada Zhan ◽  
Yali Sun ◽  
M. Shahid Mukhtar
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Tertiary Structure ◽  
Conformational Dynamics ◽  
Disordered Proteins ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Specific Proteins ◽  
Free Energy Landscapes ◽  
Dynamics Simulations ◽  
Fixed Structure

Traditional conventions that a protein’s sequence dictates its definitive, tertiary structure, and that this fixed structure provides the protein with the ability to carry out its designated role(s) are still correct but not for all proteins. Research over the past decade discovered that several key proteins possess intrinsically disordered regions (IDRs) that are crucial to their ability to perform specific functions and are observed clustered together within important classes of proteins. In this review, we aim to demonstrate how free energy landscapes, molecular dynamics simulations, and homology modeling are helpful in understanding key conformational dynamics of intrinsically disordered proteins (IDPs). Additionally, we use a list of predicted IDPs found in Arabidopsis to identify chromatin organizers and transcriptional regulators as being highly enriched in IDPs. Furthermore, we focus our attention to specific proteins within these families such as HAC5, EFS, ANAC019, ANAC013, and ANAC046. Future studies are needed to experimentally identify additional IDPs and their binding mechanisms.

scholarly journals Optimization of Molecular Dynamics Simulations of c-MYC1-88—An Intrinsically Disordered System

Life ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 109 ◽  
Author(s):  
Sandra S. Sullivan ◽  
Robert O.J. Weinzierl
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Intrinsically Disordered Proteins ◽  
Disordered Proteins ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Proliferation And Apoptosis ◽  
Conventional Structure ◽  
Experimental Approaches ◽  
Dynamics Simulations

Many of the proteins involved in key cellular regulatory events contain extensive intrinsically disordered regions that are not readily amenable to conventional structure/function dissection. The oncoprotein c-MYC plays a key role in controlling cell proliferation and apoptosis and more than 70% of the primary sequence is disordered. Computational approaches that shed light on the range of secondary and tertiary structural conformations therefore provide the only realistic chance to study such proteins. Here, we describe the results of several tests of force fields and water models employed in molecular dynamics simulations for the N-terminal 88 amino acids of c-MYC. Comparisons of the simulation data with experimental secondary structure assignments obtained by NMR establish a particular implicit solvation approach as highly congruent. The results provide insights into the structural dynamics of c-MYC1-88, which will be useful for guiding future experimental approaches. The protocols for trajectory analysis described here will be applicable for the analysis of a variety of computational simulations of intrinsically disordered proteins.

Sequence Specificity Despite Intrinsic Disorder: How a Disease-Associated Val/Met Polymorphism Shifts Tertiary Interactions in a Long Disordered Protein

2019 ◽  
Author(s):  
Ruchi Lohia ◽  
Reza Salari ◽  
Grace Brannigan
Keyword(s):  
Secondary Structure ◽  
Electrostatic Interactions ◽  
Intrinsically Disordered Proteins ◽  
Disordered Proteins ◽  
Sequence Specificity ◽  
Intrinsically Disordered ◽  
Specific Effects ◽  
Heterogeneous Polymer ◽  
Non Local ◽  
Dynamics Simulations

<div>The role of electrostatic interactions and mutations that change charge states in intrinsically disordered proteins (IDPs) is well-established, but many disease-associated mutations in IDPs are charge-neutral. The Val66Met single nucleotide polymorphism (SNP) encodes a hydrophobic-to-hydrophobic mutation at the midpoint of the prodomain of precursor brain-derived neurotrophic factor (BDNF), one of the earliest SNPs to be associated with neuropsychiatric disorders, for which the underlying molecular mechanism is unknown. Here we report on over 250 μs of fully-atomistic, explicit solvent, temperature replica exchange molecular dynamics simulations of the 91 residue BDNF prodomain, for both the V66 and M66 sequence.</div><div>The simulations were able to correctly reproduce the location of both local and non-local secondary changes due to the Val66Met mutation when compared with NMR spectroscopy. We find that the local structure change is mediated via entropic and sequence specific effects. We show that the highly disordered prodomain can be meaningfully divided into domains based on sequence alone. Monte Carlo simulations of a self-excluding heterogeneous polymer, with monomers representing each domain, suggest the sequence would be effectively segmented by the long, highly disordered polyampholyte near the sequence midpoint. This is qualitatively consistent with observed interdomain contacts within the BDNF prodomain, although contacts between the two segments are enriched relative to the self-excluding polymer. The Val66Met mutation increases interactions across the boundary between the two segments, due in part to a specific Met-Met interaction with a Methionine in the other segment. This effect propagates to cause the non-local change in secondary structure around the second methionine, previously observed in NMR. The effect is not mediated simply via changes in inter-domain contacts but is also dependent on secondary structure formation around residue 66, indicating a mechanism for secondary structure coupling in disordered proteins. </div>

scholarly journals Planar Boronic Graphene and Nitrogenized Graphene Heterostructure for Protein Stretch and Confinement

Biomolecules ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1756
Author(s):  
Xuchang Su ◽  
Zhi He ◽  
Lijun Meng ◽  
Hong Liang ◽  
Ruhong Zhou
Keyword(s):  
Single Molecule ◽  
Intrinsically Disordered Proteins ◽  
Electron Tunneling ◽  
Amyloid Β ◽  
Protein Sequencing ◽  
Disordered Proteins ◽  
Force Microscopy ◽  
Intrinsically Disordered ◽  
Atomic Force ◽  
Dynamics Simulations

Single-molecule techniques such as electron tunneling and atomic force microscopy have attracted growing interests in protein sequencing. For these methods, it is critical to refine and stabilize the protein sample to a “suitable mode” before applying a high-fidelity measurement. Here, we show that a planar heterostructure comprising boronic graphene (BC3) and nitrogenized graphene (C3N) sandwiched stripe (BC3/C3N/BC3) is capable of the effective stretching and confinement of three types of intrinsically disordered proteins (IDPs), including amyloid-β (1–42), polyglutamine (Q42), and α-Synuclein (61–95). Our molecular dynamics simulations demonstrate that the protein molecules interact more strongly with the C3N stripe than the BC3 one, which leads to their capture, elongation, and confinement along the center C3N stripe of the heterostructure. The conformational fluctuations of IDPs are substantially reduced after being stretched. This design may serve as a platform for single-molecule protein analysis with reduced thermal noise.

scholarly journals Intrinsically disordered proteins identified in the aggregate proteome serve as biomarkers of neurodegeneration

2021 ◽  
Author(s):  
Srinivas Ayyadevara ◽  
Akshatha Ganne ◽  
Meenakshisundaram Balasubramaniam ◽  
Robert J. Shmookler Reis
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Protein Complexes ◽  
Disordered Proteins ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Physiological Processes ◽  
Protein Partners ◽  
And Function ◽  
Computational Analyses ◽  
Disordered Regions

AbstractA protein’s structure is determined by its amino acid sequence and post-translational modifications, and provides the basis for its physiological functions. Across all organisms, roughly a third of the proteome comprises proteins that contain highly unstructured or intrinsically disordered regions. Proteins comprising or containing extensive unstructured regions are referred to as intrinsically disordered proteins (IDPs). IDPs are believed to participate in complex physiological processes through refolding of IDP regions, dependent on their binding to a diverse array of potential protein partners. They thus play critical roles in the assembly and function of protein complexes. Recent advances in experimental and computational analyses predicted multiple interacting partners for the disordered regions of proteins, implying critical roles in signal transduction and regulation of biological processes. Numerous disordered proteins are sequestered into aggregates in neurodegenerative diseases such as Alzheimer’s disease (AD) where they are enriched even in serum, making them good candidates for serum biomarkers to enable early detection of AD.

scholarly journals Progressive Phosphorylation Modulates the Self-Association of a Variably Modified Histone H3 Peptide

2021 ◽  
Vol 8 ◽  
Author(s):  
George V. Papamokos ◽  
George Tziatzos ◽  
Dimitrios G. Papageorgiou ◽  
Spyros Georgatos ◽  
Efthimios Kaxiras ◽  
...  
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Histone H3 ◽  
Intramolecular Interactions ◽  
Disordered Proteins ◽  
Post Translational Modifications ◽  
Intrinsically Disordered ◽  
Self Association ◽  
Dynamics Simulations ◽  
Peptide Charge

Protein phosphorylation is a key regulatory mechanism in eukaryotic cells. In the intrinsically disordered histone tails, phosphorylation is often a part of combinatorial post-translational modifications and an integral part of the “histone code” that regulates gene expression. Here, we study the association between two histone H3 tail peptides modified to different degrees, using fully atomistic molecular dynamics simulations. Assuming that the initial conformations are either α-helical or fully extended, we compare the propensity of the two peptides to associate with one another when both are unmodified, one modified and the other unmodified, or both modified. The simulations lead to the identification of distinct inter- and intramolecular interactions in the peptide dimer, highlighting a prominent role of a fine-tuned phosphorylation rheostat in peptide association. Progressive phosphorylation appears to modulate peptide charge, inducing strong and specific intermolecular interactions between the monomers, which do not result in the formation of amorphous or ordered aggregates, as documented by experimental evidence derived from Circular Dichroism and NMR spectroscopy. However, upon complete saturation of positive charges by phosphate groups, this effect is reversed: intramolecular interactions prevail and dimerization of zero-charge peptides is markedly reduced. These findings underscore the role of phosphorylation thresholds in the dynamics of intrinsically disordered proteins. Phosphorylation rheostats might account for the divergent effects of histone modifications on the modulation of chromatin structure.

From folding to function: complex macromolecular reactions unraveled one-by-one with optical tweezers

2021 ◽  
Author(s):  
Pétur O. Heidarsson ◽  
Ciro Cecconi
Keyword(s):  
Optical Tweezers ◽  
Single Molecule ◽  
Structural Changes ◽  
Intrinsically Disordered Proteins ◽  
Conformational Dynamics ◽  
Disordered Proteins ◽  
Kinase Activation ◽  
Intrinsically Disordered ◽  
Complex Protein ◽  
Methodological Principles

Abstract Single-molecule manipulation with optical tweezers has uncovered macromolecular behaviour hidden to other experimental techniques. Recent instrumental improvements have made it possible to expand the range of systems accessible to optical tweezers. Beyond focusing on the folding and structural changes of isolated single molecules, optical tweezers studies have evolved into unraveling the basic principles of complex molecular processes such as co-translational folding on the ribosome, kinase activation dynamics, ligand–receptor binding, chaperone-assisted protein folding, and even dynamics of intrinsically disordered proteins (IDPs). In this mini-review, we illustrate the methodological principles of optical tweezers before highlighting recent advances in studying complex protein conformational dynamics – from protein synthesis to physiological function – as well as emerging future issues that are beginning to be addressed with novel approaches.

scholarly journals Random coil chemical shifts for serine, threonine and tyrosine phosphorylation over a broad pH range

2019 ◽  
Vol 73 (12) ◽  
pp. 713-725 ◽  
Author(s):  
Ruth Hendus-Altenburger ◽  
Catarina B. Fernandes ◽  
Katrine Bugge ◽  
Micha B. A. Kunze ◽  
Wouter Boomsma ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Secondary Structure ◽  
Intrinsically Disordered Proteins ◽  
Chemical Shifts ◽  
Random Coil ◽  
Disordered Proteins ◽  
Phosphoryl Group ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Secondary Chemical

Abstract Phosphorylation is one of the main regulators of cellular signaling typically occurring in flexible parts of folded proteins and in intrinsically disordered regions. It can have distinct effects on the chemical environment as well as on the structural properties near the modification site. Secondary chemical shift analysis is the main NMR method for detection of transiently formed secondary structure in intrinsically disordered proteins (IDPs) and the reliability of the analysis depends on an appropriate choice of random coil model. Random coil chemical shifts and sequence correction factors were previously determined for an Ac-QQXQQ-NH2-peptide series with X being any of the 20 common amino acids. However, a matching dataset on the phosphorylated states has so far only been incompletely determined or determined only at a single pH value. Here we extend the database by the addition of the random coil chemical shifts of the phosphorylated states of serine, threonine and tyrosine measured over a range of pH values covering the pKas of the phosphates and at several temperatures (www.bio.ku.dk/sbinlab/randomcoil). The combined results allow for accurate random coil chemical shift determination of phosphorylated regions at any pH and temperature, minimizing systematic biases of the secondary chemical shifts. Comparison of chemical shifts using random coil sets with and without inclusion of the phosphoryl group, revealed under/over estimations of helicity of up to 33%. The expanded set of random coil values will improve the reliability in detection and quantification of transient secondary structure in phosphorylation-modified IDPs.

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