scholarly journals A Transferable Model For Chromosome Architecture

2016 ◽  
Author(s):  
Michele Di Pierro ◽  
Bin Zhang ◽  
Erez Lieberman Aiden ◽  
Peter G. Wolynes ◽  
José N. Onuchic
Keyword(s):  
Three Dimensional ◽  
Maximum Entropy Principle ◽  
Dimensional Structure ◽  
Open Chromatin ◽  
3D Structures ◽  
Chromosome Architecture ◽  
Contact Maps ◽  
Entropy Principle ◽  
Dynamics Simulations

AbstractIn vivo, the human genome folds into a characteristic ensemble of three-dimensional structures. The mechanism driving the folding process remains unknown. We report a theoretical model for chromatin (Minimal Chromatin Model) that explains the folding of interphase chromosomes and generates chromosome conformations consistent with experimental data. The energy landscape of the model was derived by using the maximum entropy principle and relies on two experimentally derived inputs: a classification of loci into chromatin types and a catalog of the positions of chromatin loops. First, we trained our energy function using the Hi-C contact map of chromosome 10 from human GM12878 lymphoblastoid cells. Then we used the model to perform molecular dynamics simulations producing an ensemble of 3D structures for all GM12878 autosomes. Finally, we used these 3D structures to generate contact maps. We found that simulated contact maps closely agree with experimental results for all GM12878 autosomes.The ensemble of structures resulting from these simulations exhibited unknotted chromosomes, phase separation of chromatin types, and a tendency for open chromatin to lie at the periphery of chromosome territories.One Sentence Summary:We report a model for chromatin that explains and accurately reproduces the three-dimensional structure of chromosomes in interphase.

scholarly journals Transferable model for chromosome architecture

2016 ◽  
Vol 113 (43) ◽  
pp. 12168-12173 ◽  
Author(s):  
Michele Di Pierro ◽  
Bin Zhang ◽  
Erez Lieberman Aiden ◽  
Peter G. Wolynes ◽  
José N. Onuchic
Keyword(s):  
Maximum Entropy Principle ◽  
Open Chromatin ◽  
Contact Map ◽  
3D Structures ◽  
Chromosome Architecture ◽  
Contact Maps ◽  
Entropy Principle ◽  
Dynamics Simulations

In vivo, the human genome folds into a characteristic ensemble of 3D structures. The mechanism driving the folding process remains unknown. We report a theoretical model for chromatin (Minimal Chromatin Model) that explains the folding of interphase chromosomes and generates chromosome conformations consistent with experimental data. The energy landscape of the model was derived by using the maximum entropy principle and relies on two experimentally derived inputs: a classification of loci into chromatin types and a catalog of the positions of chromatin loops. First, we trained our energy function using the Hi-C contact map of chromosome 10 from human GM12878 lymphoblastoid cells. Then, we used the model to perform molecular dynamics simulations producing an ensemble of 3D structures for all GM12878 autosomes. Finally, we used these 3D structures to generate contact maps. We found that simulated contact maps closely agree with experimental results for all GM12878 autosomes. The ensemble of structures resulting from these simulations exhibited unknotted chromosomes, phase separation of chromatin types, and a tendency for open chromatin to lie at the periphery of chromosome territories.

scholarly journals Online biophysical predictions for SARS-CoV-2 proteins

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Luciano Kagami ◽  
Joel Roca-Martínez ◽  
Jose Gavaldá-García ◽  
Pathmanaban Ramasamy ◽  
K. Anton Feenstra ◽  
...  
Keyword(s):  
Protein Sequence ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Static Structure ◽  
Homologous Proteins ◽  
Structure Based Drug Design ◽  
Protein Protein Interaction ◽  
Link Type ◽  
Dynamics Simulations ◽  
Β Sheet

Abstract Background The SARS-CoV-2 virus, the causative agent of COVID-19, consists of an assembly of proteins that determine its infectious and immunological behavior, as well as its response to therapeutics. Major structural biology efforts on these proteins have already provided essential insights into the mode of action of the virus, as well as avenues for structure-based drug design. However, not all of the SARS-CoV-2 proteins, or regions thereof, have a well-defined three-dimensional structure, and as such might exhibit ambiguous, dynamic behaviour that is not evident from static structure representations, nor from molecular dynamics simulations using these structures. Main We present a website (https://bio2byte.be/sars2/) that provides protein sequence-based predictions of the backbone and side-chain dynamics and conformational propensities of these proteins, as well as derived early folding, disorder, β-sheet aggregation, protein-protein interaction and epitope propensities. These predictions attempt to capture the inherent biophysical propensities encoded in the sequence, rather than context-dependent behaviour such as the final folded state. In addition, we provide the biophysical variation that is observed in homologous proteins, which gives an indication of the limits of their functionally relevant biophysical behaviour. Conclusion The https://bio2byte.be/sars2/ website provides a range of protein sequence-based predictions for 27 SARS-CoV-2 proteins, enabling researchers to form hypotheses about their possible functional modes of action.

scholarly journals Structure of the Lectin Mannose 6-Phosphate Receptor Homology (MRH) Domain of Glucosidase II, an Enzyme That Regulates Glycoprotein Folding Quality Control in the Endoplasmic Reticulum

2013 ◽  
Vol 288 (23) ◽  
pp. 16460-16475 ◽  
Author(s):  
Linda J. Olson ◽  
Ramiro Orsi ◽  
Solana G. Alculumbre ◽  
Francis C. Peterson ◽  
Ivan D. Stigliano ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Three Dimensional ◽  
Binding Pocket ◽  
Dimensional Structure ◽  
Mannose Residue ◽  
Glucosidase Ii ◽  
Mannose 6 Phosphate ◽  
First Time ◽  
Conserved Residue

Here we report for the first time the three-dimensional structure of a mannose 6-phosphate receptor homology (MRH) domain present in a protein with enzymatic activity, glucosidase II (GII). GII is involved in glycoprotein folding in the endoplasmic reticulum. GII removes the two innermost glucose residues from the Glc3Man9GlcNAc2 transferred to nascent proteins and the glucose added by UDP-Glc:glycoprotein glucosyltransferase. GII is composed of a catalytic GIIα subunit and a regulatory GIIβ subunit. GIIβ participates in the endoplasmic reticulum localization of GIIα and mediates in vivo enhancement of N-glycan trimming by GII through its C-terminal MRH domain. We determined the structure of a functional GIIβ MRH domain by NMR spectroscopy. It adopts a β-barrel fold similar to that of other MRH domains, but its binding pocket is the most shallow known to date as it accommodates a single mannose residue. In addition, we identified a conserved residue outside the binding pocket (Trp-409) present in GIIβ but not in other MRHs that influences GII glucose trimming activity.

scholarly journals Protein Folding: Search for Basic Physical Models

2003 ◽  
Vol 3 ◽  
pp. 623-635 ◽  
Author(s):  
Ivan Y. Torshin ◽  
Robert W. Harrison
Keyword(s):  
Protein Folding ◽  
Tertiary Structure ◽  
Three Dimensional ◽  
Physical Models ◽  
Dimensional Structure ◽  
Computational Techniques ◽  
Linear Sequence ◽  
Physical Forces

How a unique three-dimensional structure is rapidly formed from the linear sequence of a polypeptide is one of the important questions in contemporary science. Apart from biological context ofin vivoprotein folding (which has been studied only for a few proteins), the roles of the fundamental physical forces in thein vitrofolding remain largely unstudied. Despite a degree of success in using descriptions based on statistical and/or thermodynamic approaches, few of the current models explicitly include more basic physical forces (such as electrostatics and Van Der Waals forces). Moreover, the present-day models rarely take into account that the protein folding is, essentially, a rapid process that produces a highly specific architecture. This review considers several physical models that may provide more direct links between sequence and tertiary structure in terms of the physical forces. In particular, elaboration of such simple models is likely to produce extremely effective computational techniques with value for modern genomics.

scholarly journals Computational Protein Stabilization Can Affect Folding Energy Landscapes and Lead to Domain-Swapped Dimers

2021 ◽  
Author(s):  
Klara Markova ◽  
Antonin Kunka ◽  
Klaudia Chmelova ◽  
Martin Havlasek ◽  
Petra Babkova ◽  
...  
Keyword(s):  
Protein Folding ◽  
Protein Design ◽  
Energy Landscape ◽  
Single Point ◽  
Three Dimensional ◽  
Protein Stabilization ◽  
Dimensional Structure ◽  
Evolutionary Analysis ◽  
Folding Energy

<p>The functionality of a protein depends on its unique three-dimensional structure, which is a result of the folding process when the nascent polypeptide follows a funnel-like energy landscape to reach a global energy minimum. Computer-encoded algorithms are increasingly employed to stabilize native proteins for use in research and biotechnology applications. Here, we reveal a unique example where the computational stabilization of a monomeric α/β-hydrolase enzyme (<i>T</i><sub>m</sub> = 73.5°C; Δ<i>T</i><sub>m</sub> > 23°C) affected the protein folding energy landscape. Introduction of eleven single-point stabilizing mutations based on force field calculations and evolutionary analysis yielded catalytically active domain-swapped intermediates trapped in local energy minima. Crystallographic structures revealed that these stabilizing mutations target cryptic hinge regions and newly introduced secondary interfaces, where they make extensive non-covalent interactions between the intertwined misfolded protomers. The existence of domain-swapped dimers in a solution is further confirmed experimentally by data obtained from SAXS and crosslinking mass spectrometry. Unfolding experiments showed that the domain-swapped dimers can be irreversibly converted into native-like monomers, suggesting that the domain-swapping occurs exclusively <i>in vivo</i>. Our findings uncovered hidden protein-folding consequences of computational protein design, which need to be taken into account when applying a rational stabilization to proteins of biological and pharmaceutical interest.</p>

scholarly journals Computational Protein Stabilization Can Affect Folding Energy Landscapes and Lead to Domain-Swapped Dimers

2021 ◽  
Author(s):  
Klara Markova ◽  
Antonin Kunka ◽  
Klaudia Chmelova ◽  
Martin Havlasek ◽  
Petra Babkova ◽  
...  
Keyword(s):  
Protein Folding ◽  
Protein Design ◽  
Energy Landscape ◽  
Single Point ◽  
Three Dimensional ◽  
Protein Stabilization ◽  
Dimensional Structure ◽  
Evolutionary Analysis ◽  
Folding Energy

<p>The functionality of a protein depends on its unique three-dimensional structure, which is a result of the folding process when the nascent polypeptide follows a funnel-like energy landscape to reach a global energy minimum. Computer-encoded algorithms are increasingly employed to stabilize native proteins for use in research and biotechnology applications. Here, we reveal a unique example where the computational stabilization of a monomeric α/β-hydrolase enzyme (<i>T</i><sub>m</sub> = 73.5°C; Δ<i>T</i><sub>m</sub> > 23°C) affected the protein folding energy landscape. Introduction of eleven single-point stabilizing mutations based on force field calculations and evolutionary analysis yielded catalytically active domain-swapped intermediates trapped in local energy minima. Crystallographic structures revealed that these stabilizing mutations target cryptic hinge regions and newly introduced secondary interfaces, where they make extensive non-covalent interactions between the intertwined misfolded protomers. The existence of domain-swapped dimers in a solution is further confirmed experimentally by data obtained from SAXS and crosslinking mass spectrometry. Unfolding experiments showed that the domain-swapped dimers can be irreversibly converted into native-like monomers, suggesting that the domain-swapping occurs exclusively <i>in vivo</i>. Our findings uncovered hidden protein-folding consequences of computational protein design, which need to be taken into account when applying a rational stabilization to proteins of biological and pharmaceutical interest.</p>

scholarly journals Antibodies against Thrombospondin-Related Anonymous Protein Do Not Inhibit Plasmodium Sporozoite Infectivity In Vivo

2000 ◽  
Vol 68 (6) ◽  
pp. 3667-3673 ◽  
Author(s):  
Soren Gantt ◽  
Cathrine Persson ◽  
Keith Rose ◽  
Ashley J. Birkett ◽  
Ruben Abagyan ◽  
...  
Keyword(s):  
Metal Ion ◽  
Competitive Inhibition ◽  
Polyclonal Antibodies ◽  
Three Dimensional ◽  
Calcium Ionophore ◽  
Plasmodium Yoelii ◽  
Gliding Motility ◽  
Vaccine Antigen ◽  
Dimensional Structure

ABSTRACT Thrombospondin-related anonymous protein (TRAP), a candidate malaria vaccine antigen, is required for Plasmodiumsporozoite gliding motility and cell invasion. For the first time, the ability of antibodies against TRAP to inhibit sporozoite infectivity in vivo is evaluated in detail. TRAP contains an A-domain, a well-characterized adhesive motif found in integrins. We modeled here a three-dimensional structure of the TRAP A-domain of Plasmodium yoelii and located regions surrounding the MIDAS (metal ion-dependent adhesion site), the presumed business end of the domain. Mice were immunized with constructs containing these A-domain regions but were not protected from sporozoite challenge. Furthermore, monoclonal and rabbit polyclonal antibodies against the A-domain, the conserved N terminus, and the repeat region of TRAP had no effect on the gliding motility or sporozoite infectivity to mice. TRAP is located in micronemes, secretory organelles of apicomplexan parasites. Accordingly, the antibodies tested here stained cytoplasmic TRAP brightly by immunofluorescence. However, very little TRAP could be detected on the surface of sporozoites. In contrast, a dramatic relocalization of TRAP onto the parasite surface occurred when sporozoites were treated with calcium ionophore. This likely mimics the release of TRAP from micronemes when a sporozoite contacts its target cell in vivo. Contact with hepatoma cells in culture also appeared to induce the release of TRAP onto the surface of sporozoites. If large amounts of TRAP are released in close proximity to its cellular receptor(s), effective competitive inhibition by antibodies may be difficult to achieve.

scholarly journals Role of YidC in folding of polytopic membrane proteins

2004 ◽  
Vol 165 (1) ◽  
pp. 53-62 ◽  
Author(s):  
Shushi Nagamori ◽  
Irina N. Smirnova ◽  
H. Ronald Kaback
Keyword(s):  
Membrane Proteins ◽  
Three Dimensional ◽  
In Vitro Transcription ◽  
Dimensional Structure ◽  
Lipid Phase ◽  
Lactose Permease ◽  
Primary Role ◽  
Protein Insertion

YidC of Echerichia coli, a member of the conserved Alb3/Oxa1/YidC family, is postulated to be important for biogenesis of membrane proteins. Here, we use as a model the lactose permease (LacY), a membrane transport protein with a known three-dimensional structure, to determine whether YidC plays a role in polytopic membrane protein insertion and/or folding. Experiments in vivo and with an in vitro transcription/translation/insertion system demonstrate that YidC is not necessary for insertion per se, but plays an important role in folding of LacY. By using the in vitro system and two monoclonal antibodies directed against conformational epitopes, LacY is shown to bind the antibodies poorly in YidC-depleted membranes. Moreover, LacY also folds improperly in proteoliposomes prepared without YidC. However, when the proteoliposomes are supplemented with purified YidC, LacY folds correctly. The results indicate that YidC plays a primary role in folding of LacY into its final tertiary conformation via an interaction that likely occurs transiently during insertion into the lipid phase of the membrane.

scholarly journals Insights into the molecular basis of sperm–egg recognition in mammals

Reproduction ◽  
2004 ◽  
Vol 127 (4) ◽  
pp. 417-422 ◽  
Author(s):  
Tanya Hoodbhoy ◽  
Jurrien Dean
Keyword(s):  
Zona Pellucida ◽  
Three Dimensional ◽  
Explanatory Models ◽  
Dimensional Structure ◽  
Side Chain ◽  
Egg Recognition ◽  
Three Dimensional Structure ◽  
Sperm Binding ◽  
Single Protein

The zona pellucida surrounding the egg and pre-implantation embryo is required for in vivo fertility and early development. Explanatory models of sperm–egg recognition need to take into account the ability of sperm to bind to ovulated eggs, but not to two-cell embryos. For the last two decades, investigators have sought to identify an individual protein or carbohydrate side chain as the ‘sperm receptor’. However, recent genetic data in mice are more consistent with the three-dimensional structure of the zona pellucida, rather than a single protein (or carbohydrate), determining sperm binding. The mouse and human zonae pellucidae contain three glycoproteins (ZP1, ZP2, ZP3) and, following fertilization, ZP2 is proteolytically cleaved. The replacement of endogenous mouse proteins with human ZP2, ZP3 or both does not alter taxon specificity of sperm binding or prevent fertility. Surprisingly, human ZP2 is not cleaved following fertilization and intact ZP2 correlates with persistent sperm binding to two-cell embryos. Taken together, these data support a model in which the cleavage status of ZP2 modulates the three-dimensional structure of the zona pellucida and determines whether sperm bind (uncleaved) or do not (cleaved).

scholarly journals FT-COMAR: fault tolerant three-dimensional structure reconstruction from protein contact maps

2008 ◽  
Vol 24 (10) ◽  
pp. 1313-1315 ◽  
Author(s):  
Marco Vassura ◽  
Luciano Margara ◽  
Pietro Di Lena ◽  
Filippo Medri ◽  
Piero Fariselli ◽  
...  
Keyword(s):  
Fault Tolerant ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Contact Maps ◽  
Structure Reconstruction ◽  
Protein Contact Maps
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