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Author: Philip W. Bransford
Publisher:
ISBN:
Category :
Languages : en
Pages : 145
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Book Description
The volume of protein structure data has grown rapidly over the past 30 years, leaving a wake of facts that still require explanation. We endeavored to answer a few open questions on the structure-function relationship of intriguing mechanochemical protein systems. To this end this thesis work contains five studies that offer novel insights into molecular biomechanical systems that may guide future basic research or applications development. The first study concerns the biophysics of cadherin-mediated cell sorting observed in developing solid tissue. We investigated the evolutionary dynamics of the cadherin superfamily of cell-cell adhesion proteins to infer a structural basis for their paradoxical mixture of pairwise binding specificity and promiscuity. Our analysis predicts a small set of specificity-determining residues located within the protomer-protomer binding interface. The putative specificity-determinants form a design space with potential for engineering novel cell-cell adhesive interactions. The second study addresses the open question of how to automatically identify regions within a protein that engage in allosteric communication. To identify allostery we developed and tested two computational tools that operate on protein conformational dynamics data. These tools are useful for generating testable hypotheses about proteins with multiple functional sites for the design of non-competitive protein inhibitors. The third study asks, "What is the consequence of allosteric cooperation between the tandem binding sites in a class of proteins that bundle filamentous actin (F-actin)?" Through simulation we demonstrate that cooperative F-actin bundling tends to strengthen bundles by driving the formation of cross-links between neighboring filaments while depleting F-actin binding sites that are occupied but not cross-linked. We hence propose that allostery may be a natural feature of ABPs with tandem F-actin binding sites if nature indeed selects for sturdy F-actin bundles. The final two studies examine the impact of two structural perturbations to Factin on its mechanics. Using structure-based computer modeling we develop a simple explanation for the mechanism by which the structure of actin's polymorphic subdomain 2 mediates 4-fold changes in F-actin's flexibility. We further demonstrate that two calponin homology domains stabilize F-actin by binding in a configuration that tends to relax the stress concentration at actin-actin interfaces.
Author: Philip W. Bransford
Publisher:
ISBN:
Category :
Languages : en
Pages : 145
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Book Description
The volume of protein structure data has grown rapidly over the past 30 years, leaving a wake of facts that still require explanation. We endeavored to answer a few open questions on the structure-function relationship of intriguing mechanochemical protein systems. To this end this thesis work contains five studies that offer novel insights into molecular biomechanical systems that may guide future basic research or applications development. The first study concerns the biophysics of cadherin-mediated cell sorting observed in developing solid tissue. We investigated the evolutionary dynamics of the cadherin superfamily of cell-cell adhesion proteins to infer a structural basis for their paradoxical mixture of pairwise binding specificity and promiscuity. Our analysis predicts a small set of specificity-determining residues located within the protomer-protomer binding interface. The putative specificity-determinants form a design space with potential for engineering novel cell-cell adhesive interactions. The second study addresses the open question of how to automatically identify regions within a protein that engage in allosteric communication. To identify allostery we developed and tested two computational tools that operate on protein conformational dynamics data. These tools are useful for generating testable hypotheses about proteins with multiple functional sites for the design of non-competitive protein inhibitors. The third study asks, "What is the consequence of allosteric cooperation between the tandem binding sites in a class of proteins that bundle filamentous actin (F-actin)?" Through simulation we demonstrate that cooperative F-actin bundling tends to strengthen bundles by driving the formation of cross-links between neighboring filaments while depleting F-actin binding sites that are occupied but not cross-linked. We hence propose that allostery may be a natural feature of ABPs with tandem F-actin binding sites if nature indeed selects for sturdy F-actin bundles. The final two studies examine the impact of two structural perturbations to Factin on its mechanics. Using structure-based computer modeling we develop a simple explanation for the mechanism by which the structure of actin's polymorphic subdomain 2 mediates 4-fold changes in F-actin's flexibility. We further demonstrate that two calponin homology domains stabilize F-actin by binding in a configuration that tends to relax the stress concentration at actin-actin interfaces.
Author: Ke-li Han
Publisher: Springer Science & Business Media
ISBN: 3319029703
Category : Medical
Languages : en
Pages : 488
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Book Description
This book discusses how biological molecules exert their function and regulate biological processes, with a clear focus on how conformational dynamics of proteins are critical in this respect. In the last decade, the advancements in computational biology, nuclear magnetic resonance including paramagnetic relaxation enhancement, and fluorescence-based ensemble/single-molecule techniques have shown that biological molecules (proteins, DNAs and RNAs) fluctuate under equilibrium conditions. The conformational and energetic spaces that these fluctuations explore likely contain active conformations that are critical for their function. More interestingly, these fluctuations can respond actively to external cues, which introduces layers of tight regulation on the biological processes that they dictate. A growing number of studies have suggested that conformational dynamics of proteins govern their role in regulating biological functions, examples of this regulation can be found in signal transduction, molecular recognition, apoptosis, protein / ion / other molecules translocation and gene expression. On the experimental side, the technical advances have offered deep insights into the conformational motions of a number of proteins. These studies greatly enrich our knowledge of the interplay between structure and function. On the theoretical side, novel approaches and detailed computational simulations have provided powerful tools in the study of enzyme catalysis, protein / drug design, protein / ion / other molecule translocation and protein folding/aggregation, to name but a few. This work contains detailed information, not only on the conformational motions of biological systems, but also on the potential governing forces of conformational dynamics (transient interactions, chemical and physical origins, thermodynamic properties). New developments in computational simulations will greatly enhance our understanding of how these molecules function in various biological events.
Author: Brandon Mac Butler
Publisher:
ISBN:
Category : DNA-protein interactions
Languages : en
Pages : 135
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Book Description
Proteins are essential for most biological processes that constitute life. The function of a protein is encoded within its 3D folded structure, which is determined by its sequence of amino acids. A variation of a single nucleotide in the DNA during transcription (nSNV) can alter the amino acid sequence (i.e., a mutation in the protein sequence), which can adversely impact protein function and sometimes cause disease. These mutations are the most prevalent form of variations in humans, and each individual genome harbors tens of thousands of nSNVs that can be benign (neutral) or lead to disease. The primary way to assess the impact of nSNVs on function is through evolutionary approaches based on positional amino acid conservation. These approaches are largely inadequate in the regime where positions evolve at a fast rate. We developed a method called dynamic flexibility index (DFI) that measures site-specific conformational dynamics of a protein, which is paramount in exploring mechanisms of the impact of nSNVs on function. In this thesis, we demonstrate that DFI can distinguish the disease-associated and neutral nSNVs, particularly for fast evolving positions where evolutionary approaches lack predictive power. We also describe an additional dynamics-based metric, dynamic coupling index (DCI), which measures the dynamic allosteric residue coupling of distal sites on the protein with the functionally critical (i.e., active) sites. Through DCI, we analyzed 200 disease mutations of a specific enzyme called GCase, and a proteome-wide analysis of 75 human enzymes containing 323 neutral and 362 disease mutations. In both cases we observed that sites with high dynamic allosteric residue coupling with the functional sites (i.e., DARC spots) have an increased susceptibility to harboring disease nSNVs. Overall, our comprehensive proteome-wide analysis suggests that incorporating these novel position-specific conformational dynamics based metrics into genomics can complement current approaches to increase the accuracy of diagnosing disease nSNVs. Furthermore, they provide mechanistic insights about disease development. Lastly, we introduce a new, purely sequence-based model that can estimate the dynamics profile of a protein by only utilizing coevolution information, eliminating the requirement of the 3D structure for determining dynamics.
Author: Ivet Bahar
Publisher: Garland Science
ISBN: 1351815016
Category : Science
Languages : en
Pages : 337
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Book Description
Protein Actions: Principles and Modeling is aimed at graduates, advanced undergraduates, and any professional who seeks an introduction to the biological, chemical, and physical properties of proteins. Broadly accessible to biophysicists and biochemists, it will be particularly useful to student and professional structural biologists and molecular biophysicists, bioinformaticians and computational biologists, biological chemists (particularly drug designers) and molecular bioengineers. The book begins by introducing the basic principles of protein structure and function. Some readers will be familiar with aspects of this, but the authors build up a more quantitative approach than their competitors. Emphasizing concepts and theory rather than experimental techniques, the book shows how proteins can be analyzed using the disciplines of elementary statistical mechanics, energetics, and kinetics. These chapters illuminate how proteins attain biologically active states and the properties of those states. The book ends with a synopsis the roles of computational biology and bioinformatics in protein science.
Author: James Solomon Fraser
Publisher:
ISBN:
Category :
Languages : en
Pages : 208
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Book Description
Proteins populate structural ensembles. Defining these ensembles and understanding the role of the interconversions between structures is a grand challenge of structural biology. My work addresses that challenge through the development and application of new methods to reveal sparsely populated structures. Quantitative electron-density map interpretation, implemented in Ringer, provides an objective, systematic method to identify previously undiscovered alternate side chain substates that mediate conformational transitions in proteins. Next, I applied these methods to study the role of the interconversions of an enzyme, the human proline isomerase CypA, between two conformations during its catalytic cycle. Using the dual strategies of ambient-temperature X-ray crystallographic data collection and automated electron-density sampling, I defined the previously undiscovered minor state as a network of alternate side chain conformations. A conservative mutation outside the active site inverts the equilibrium between the substates and causes large, parallel reductions in the conformational interconversion rates and the catalytic rate. The temperature dependent differences in electron density observed with CypA led me to critically examine the assumption that crystal freezing does not significantly bias protein structure. I found extensive remodeling of the crystal lattice upon freezing. Crystal freezing also leads to improved packing through reduction of small voids and a reduction in protein volume. I used real-space electron density sampling to show that these voids can be transiently populated by alternate conformations in the room temperature ensemble. This work shows how crystal freezing biases our understanding of protein packing and can lead to differences in the spatial distribution of the dynamic features of protein side chains. These studies highlight the importance of conformational diversity in protein function. By looking beyond the model and into the map, we can find that polysteric regions often populate conformations that resemble the structures populated along reaction or evolutionary trajectories. Thus, understanding polysterism yields insights into where a protein might visit during its reaction cycle and where it has been during its evolution.
Author: Daniel J. Rigden
Publisher: Springer
ISBN: 9402410694
Category : Science
Languages : en
Pages : 509
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Book Description
This book is about protein structural bioinformatics and how it can help understand and predict protein function. It covers structure-based methods that can assign and explain protein function based on overall folds, characteristics of protein surfaces, occurrence of small 3D motifs, protein-protein interactions and on dynamic properties. Such methods help extract maximum value from new experimental structures, but can often be applied to protein models. The book also, therefore, provides comprehensive coverage of methods for predicting or inferring protein structure, covering all structural classes from globular proteins and their membrane-resident counterparts to amyloid structures and intrinsically disordered proteins. The book is split into two broad sections, the first covering methods to generate or infer protein structure, the second dealing with structure-based function annotation. Each chapter is written by world experts in the field. The first section covers methods ranging from traditional homology modelling and fold recognition to fragment-based ab initio methods, and includes a chapter, new for the second edition, on structure prediction using evolutionary covariance. Membrane proteins and intrinsically disordered proteins are each assigned chapters, while two new chapters deal with amyloid structures and means to predict modes of protein-protein interaction. The second section includes chapters covering functional diversity within protein folds and means to assign function based on surface properties and recurring motifs. Further chapters cover the key roles of protein dynamics in protein function and use of automated servers for function inference. The book concludes with two chapters covering case studies of structure prediction, based respectively on crystal structures and protein models, providing numerous examples of real-world usage of the methods mentioned previously. This book is targeted at postgraduate students and academic researchers. It is most obviously of interest to protein bioinformaticians and structural biologists, but should also serve as a guide to biologists more broadly by highlighting the insights that structural bioinformatics can provide into proteins of their interest.
Author: Robert Pilstål
Publisher: Linköping University Electronic Press
ISBN: 9176853470
Category :
Languages : en
Pages : 206
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Book Description
We are compounded entities, given life by a complex molecular machinery. When studying these molecules we have to make sense of a diverse set of dynamical nanostructures with wast and intricate patterns of interactions. Protein polymers is one of the major groups of building blocks of such nanostructures which fold up into more or less distinct three dimensional structures. Due to their shape, dynamics and chemical properties proteins are able to perform a plethora of specific functions essential to all known cellular lifeforms. The connection between protein sequence, translated into protein structure and in the continuation into protein function is well accepted but poorly understood. Malfunction in the process of protein folding is known to be implicated in natural aging, cancer and degenerative diseases such as Alzheimer's. Protein folds are described hierarchically by structural ontologies such as SCOP, CATH and Pfam all which has yet to succeed in deciphering the natural language of protein function. These paradigmatic views centered on protein structure fail to describe more mutable entities, such as intrinsically disordered proteins (IDPs) which lack a clear defined structure. As of 2012, about two thirds of cancer patients was predicted to survive past 5 years of diagnosis. Despite this, about a third do not survive and numerous of successfully treated patients suffer from secondary conditions due to chemotherapy, surgery and the like. In order to handle cancer more efficiently we have to better understand the underlying molecular mechanisms. Elusive to standard methods of investigation, IDPs have a central role in pathology; dysfunction in IDPs are key factors in cellular system failures such as cancer, as many IDPs are hub regulators for major cell functions. These IDPs carry short conserved functional boxes, that are not described by known ontologies, which suggests the existence of a smaller entity. In an investigation of a pair of such boxes of c-MYC, a plausible structural model of its interacting with Pin1 emerged, but such a model still leaves the observer with a puzzle of understanding the actual function of that interaction. If the protein is represented as a graph and modeled as the interaction patterns instead of as a structural entity, another picture emerges. As a graph, there is a parable from that of the boxes of IDPs, to that of sectors of allosterically connected residues and the theory of foldons and folding units. Such a description is also useful in deciphering the implications of specific mutations. In order to render a functional description feasible for both structured and disordered proteins, there is a need of a model separate from form and structure. Realized as protein primes, patterns of interaction, which has a specific function that can be defined as prime interactions and context. With function defined as interactions, it might be possible that the discussion of proteins and their mechanisms is thereby simplified to the point rendering protein structural determination merely supplementary to understanding protein function. Människan byggs upp av celler, de i sin tur består av än mindre beståndsdelar; livets molekyler. Dessa fungerar som mekaniska byggstenar, likt maskiner och robotar som sliter vid fabrikens band; envar utförandes en absolut nödvändig funktion för cellens, och hela kroppens, fortsatta överlevnad. De av livets molekyler som beskrivs centralt i den här avhandling är proteiner, vilka i sin tur består utav en lång kedja, med olika typer av länkar, som likt garn lindar upp sig i ett nystan av en (mer eller mindre...) bestämd struktur som avgör dess roll och funktion i cellen. Intrinsiellt oordnade proteiner (IDP) går emot denna enkla åskådning; de är proteiner som saknar struktur och beter sig mer likt spaghetti i vatten än en maskin. IDP är ändå funktionella och bär på centrala roller i cellens maskineri; exempel är oncoproteinet c-Myc som agerar "gaspedal" för cellen - fel i c-Myc's funktion leder till att cellerna löper amok, delar sig hejdlöst och vi får cancer. Man har upptäckt att c-Myc har en ombytlig struktur vi inte kan se; studier av punktvisa förändringar, mutationer, i kedjan av byggstenar hos c-Myc visar att många länkar har viktiga roller i funktionen. Detta ger oss bättre förståelse om cancer men samtidigt är laboratoriearbetet både komplicerat och dyrt; här kan evolutionen vägleda oss och avslöja hemligheterna snabbare. Molekylär evolution studeras genom att beräkna variation i proteinkedjan mellan besläktade arter som finns lagrade i databaser; detta visar snabbt, via nätverksanalys och grafteori, vilka delar av proteinet som är centrala och kopplade till varandra av nödvändighet för artens fortlevnad. På så vis hjälper evolutionen oss att förstå proteinfunktioner via modeller baserade på proteinernas interaktioner snarare än deras struktur. Samma modeller kan nyttjas för att förstå dynamiska förlopp och skillnader mellan normala och patologiska varianter av proteiner; mutationer kan uppstå i vår arvsmassa som kan leda till sjukdom. Genom analys av proteinernas kopplingsnätverk i grafmodellerna kan man bättre förutsäga vilka mutationer som är farligare än andra. Dessutom har det visat sig att en sådan representation kan ge bättre förståelse för den normala funktionen hos ett protein än vad en proteinstruktur kan. Här introduceras även konceptet proteinprimärer, vilket är en abstrakt representation av proteiner centrerad på deras interaktiva mönster, snarare än på partikulär form och struktur. Det är en förhoppning att en sådan representation skall förenkla diskussionen anbelangande proteinfunktion så till den grad att strukturbestämmelse av proteiner, som är en mycket kostsam och tidskrävande process, till viss mån kan anses vara sekundär i betydelse jämfört med funktionellt modellerande baserat på evolutionära data extraherade ur våra sekvensdatabaser.
Author: Paul Douglas Williams
Publisher:
ISBN:
Category :
Languages : en
Pages : 222
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Book Description
Author: Jeffrey M. Koshi
Publisher:
ISBN:
Category :
Languages : en
Pages : 192
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Book Description
Author: Tyler J. Glembo
Publisher:
ISBN:
Category : Mutation (Biology)
Languages : en
Pages : 175
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Book Description
Proteins are a fundamental unit in biology. Although proteins have been extensively studied, there is still much to investigate. The mechanism by which proteins fold into their native state, how evolution shapes structural dynamics, and the dynamic mechanisms of many diseases are not well understood. In this thesis, protein folding is explored using a multi-scale modeling method including (i) geometric constraint based simulations that efficiently search for native like topologies and (ii) reservoir replica exchange molecular dynamics, which identify the low free energy structures and refines these structures toward the native conformation. A test set of eight proteins and three ancestral steroid receptor proteins are folded to 2.7Å all-atom RMSD from their experimental crystal structures. Protein evolution and disease associated mutations (DAMs) are most commonly studied by in silico multiple sequence alignment methods. Here, however, the structural dynamics are incorporated to give insight into the evolution of three ancestral proteins and the mechanism of several diseases in human ferritin protein. The differences in conformational dynamics of these.
