scholarly journals Identification of Conomarphin Variants in the Conus eburneus Venom and the Effect of Sequence and PTM Variations on Conomarphin Conformations

Marine Drugs ◽  
2020 ◽  
Vol 18 (10) ◽  
pp. 503
Author(s):  
Corazon Ericka Mae M. Itang ◽  
Jokent T. Gaza ◽  
Dan Jethro M. Masacupan ◽  
Dessa Camille R. Batoctoy ◽  
Yu-Ju Chen ◽  
...  
Keyword(s):  
Amino Acid Residues ◽  
Cone Snail ◽  
M Gene ◽  
Post Translational Modifications ◽  
Hydrogen Bond Networks ◽  
Carboxyglutamic Acid ◽  
Conformational Variations ◽  
Neuroactive Peptides ◽  
Proteome Profile ◽  
Dynamics Simulations

Marine cone snails belonging to the Conidae family make use of neuroactive peptides in their venom to capture prey. Here we report the proteome profile of the venom duct of Conus eburneus, a cone snail belonging to the Tesseliconus clade. Through tandem mass spectrometry and database searching against the C. eburneus transcriptome and the ConoServer database, we identified 24 unique conopeptide sequences in the venom duct. The majority of these peptides belong to the T and M gene superfamilies and are disulfide-bonded, with cysteine frameworks V, XIV, VI/VII, and III being the most abundant. All seven of the Cys-free peptides are conomarphin variants belonging to the M superfamily that eluted out as dominant peaks in the chromatogram. These conomarphins vary not only in amino acid residues in select positions along the backbone but also have one or more post-translational modifications (PTMs) such as proline hydroxylation, C-term amidation, and γ-carboxylation of glutamic acid. Using molecular dynamics simulations, the conomarphin variants were predicted to predominantly have hairpin-like or elongated structures in acidic pH. These two structures were found to have significant differences in electrostatic properties and the inclusion of PTMs seems to complement this disparity. The presence of polar PTMs (hydroxyproline and γ-carboxyglutamic acid) also appear to stabilize hydrogen bond networks in these conformations. Furthermore, these predicted structures are pH sensitive, becoming more spherical and compact at higher pH. The subtle conformational variations observed here might play an important role in the selection and binding of the peptides to their molecular targets.

scholarly journals Oxidative Modified Fibrinogen in Cardiovascular Diseases

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5011-5011
Author(s):  
Jana Štikarová ◽  
Jiri Suttnar ◽  
Zofie Sovova ◽  
Eliska Ceznerova ◽  
Jaromir Novak ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Molecular Dynamics ◽  
Amino Acids ◽  
Czech Republic ◽  
Cardiovascular Diseases ◽  
Control Group ◽  
Amino Acid Residues ◽  
Post Translational Modifications ◽  
Dynamics Simulations

Abstract Background Cardiovascular diseases are linked with oxidative stress which is the source of reactive oxidative and nitrative species, contributors of post-translational modification. Fibrinogen due to its high concentration in blood is considered as one of the most sought of targets of oxidative stress substances. Post-translational modifications of fibrinogen might influence its physiological function, thus affect hemostasis in the terms of fibrin nets forming and architecture or interaction with platelets. The aim of this study was to observe influence of in vivo fibrinogen modifications on formation of fibrin net and to identify amino acid residues prone to changes related to oxidative stress. Methods Plasma samples were collected from patients of The Military University Hospital Prague in the agreement with ethical committees of participating institutions and with informed consents from all subjects. Samples were divided into 4 groups: patients with acute coronary syndrome (A), patients with stroke (B), patients with thrombus localized in carotid vein (C) and control group (patients without coronary atherosclerosis; D). Fibrin net architecture was studied by scanning electron microscopy (Mira 3 LMH, Tescan Orsay Holding, a.s., Brno, Czech Republic). For identification of modified amino acids residue mass spectroscopy was used (Triple TOF 6600, Sciex). Molecular dynamics simulations of hydrated protein were performed in Gromacs software with Gromos force fields. Crystal structure 3GHG was used as a reference structure to which post-translational modifications were introduced manually in Yasara View. Results We found extensive both qualitative and quantitative changes in the structure of fibrinogen molecule in all groups of patients. Oxidative stress level differed among patient groups and between the control group. Different oxidative changes caused by in vivo modifications of fibrinogen affected quite distinctly the architecture of fibrin net. Modified amino acids were detected in all three fibrinogen chains. In gamma chain the localisation of modified amino acid residues correlated with the part of fibrinogen important for fibrin polymerisation. The impact of the most pronounced post-translational modifications on the secondary structure of fibrinogen was described by molecular dynamics simulations. Conclusions The results show that the degree of impairment of fibrinogen functions in the cardiovascular diseases is related to the level of oxidative stress. Characterization of oxidative fibrinogen modification and its precise meaning to the function of fibrinogen in hemostasis appears to be extremely helpful to better understanding of thrombotic/bleeding complications linked with various cardiovascular diseases. Acknowledgments This work was supported by the Ministry of Health, Czech Republic, no. 00023736, by the Academy of Sciences, Czech Republic no. P205/12/G118 and NV18-08-00149, by ERDF OPPK CZ.2.16/3.1.00/24001 and by the European Regional Development Fund and the state budget of the Czech Republic (project AIIHHP: CZ.02.1.01/0.0/0.0/16_025/0007428, OP RDE, Ministry of Education, Youth and Sports). Disclosures No relevant conflicts of interest to declare.

Dicarbonyl derived post-translational modifications: chemistry bridging biology and aging-related disease

2020 ◽  
Vol 64 (1) ◽  
pp. 97-110
Author(s):  
Christian Sibbersen ◽  
Mogens Johannsen
Keyword(s):  
Mass Spectrometry ◽  
Future Research ◽  
Amino Acid Residues ◽  
Post Translational Modification ◽  
Dicarbonyl Compounds ◽  
Protein Targets ◽  
Post Translational Modifications ◽  
Reactive Protein ◽  
Glycation End Products ◽  
Direct Mass Spectrometry

Abstract In living systems, nucleophilic amino acid residues are prone to non-enzymatic post-translational modification by electrophiles. α-Dicarbonyl compounds are a special type of electrophiles that can react irreversibly with lysine, arginine, and cysteine residues via complex mechanisms to form post-translational modifications known as advanced glycation end-products (AGEs). Glyoxal, methylglyoxal, and 3-deoxyglucosone are the major endogenous dicarbonyls, with methylglyoxal being the most well-studied. There are several routes that lead to the formation of dicarbonyl compounds, most originating from glucose and glucose metabolism, such as the non-enzymatic decomposition of glycolytic intermediates and fructosyl amines. Although dicarbonyls are removed continuously mainly via the glyoxalase system, several conditions lead to an increase in dicarbonyl concentration and thereby AGE formation. AGEs have been implicated in diabetes and aging-related diseases, and for this reason the elucidation of their structure as well as protein targets is of great interest. Though the dicarbonyls and reactive protein side chains are of relatively simple nature, the structures of the adducts as well as their mechanism of formation are not that trivial. Furthermore, detection of sites of modification can be demanding and current best practices rely on either direct mass spectrometry or various methods of enrichment based on antibodies or click chemistry followed by mass spectrometry. Future research into the structure of these adducts and protein targets of dicarbonyl compounds may improve the understanding of how the mechanisms of diabetes and aging-related physiological damage occur.

Schistosomal Sulfotransferase Interaction with Oxamniquine Involves Hybrid Mechanism of Induced-fit and Conformational Selection

2020 ◽  
Vol 16 (4) ◽  
pp. 451-459 ◽  
Author(s):  
Fortunatus C. Ezebuo ◽  
Ikemefuna C. Uzochukwu
Keyword(s):  
Molecular Dynamics ◽  
Amino Acid ◽  
Binding Energy ◽  
Binding Site ◽  
Conformational Dynamics ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Conformational Selection ◽  
Hybrid Mechanism ◽  
Dynamics Simulations

Background: Sulfotransferase family comprises key enzymes involved in drug metabolism. Oxamniquine is a pro-drug converted into its active form by schistosomal sulfotransferase. The conformational dynamics of side-chain amino acid residues at the binding site of schistosomal sulfotransferase towards activation of oxamniquine has not received attention. Objective: The study investigated the conformational dynamics of binding site residues in free and oxamniquine bound schistosomal sulfotransferase systems and their contribution to the mechanism of oxamniquine activation by schistosomal sulfotransferase using molecular dynamics simulations and binding energy calculations. Methods: Schistosomal sulfotransferase was obtained from Protein Data Bank and both the free and oxamniquine bound forms were subjected to molecular dynamics simulations using GROMACS-4.5.5 after modeling it’s missing amino acid residues with SWISS-MODEL. Amino acid residues at its binding site for oxamniquine was determined and used for Principal Component Analysis and calculations of side-chain dihedrals. In addition, binding energy of the oxamniquine bound system was calculated using g_MMPBSA. Results: The results showed that binding site amino acid residues in free and oxamniquine bound sulfotransferase sampled different conformational space involving several rotameric states. Importantly, Phe45, Ile145 and Leu241 generated newly induced conformations, whereas Phe41 exhibited shift in equilibrium of its conformational distribution. In addition, the result showed binding energy of -130.091 ± 8.800 KJ/mol and Phe45 contributed -9.8576 KJ/mol. Conclusion: The results showed that schistosomal sulfotransferase binds oxamniquine by relying on hybrid mechanism of induced fit and conformational selection models. The findings offer new insight into sulfotransferase engineering and design of new drugs that target sulfotransferase.

scholarly journals A QM/MM Evaluation of the Missing Step in the Reduction Mechanism of HMG-CoA by Human HMG-CoA Reductase

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1085
Author(s):  
Paula Mihaljević-Jurič ◽  
Sérgio F. Sousa
Keyword(s):  
Mevalonate Pathway ◽  
Atomic Level ◽  
Amino Acid Residues ◽  
Protonation State ◽  
Primary Target ◽  
Cholesterol Levels ◽  
The Subject ◽  
Electron Reduction ◽  
Dynamics Simulations ◽  
Coa Reductase

Statins are important drugs in the regulation of cholesterol levels in the human body that have as a primary target the enzyme β-hydroxy-β-methylglutaryl-CoA reductase (HMGR). This enzyme plays a crucial role in the mevalonate pathway, catalyzing the four-electron reduction of HMG-CoA to mevalonate. A second reduction step of this reaction mechanism has been the subject of much speculation in the literature, with different conflicting theories persisting to the present day. In this study, the different mechanistic hypotheses were evaluated with atomic-level detail through a combination of molecular dynamics simulations (MD) and quantum mechanics/molecular mechanics (QM/MM) calculations. The obtained Gibbs free activation and Gibbs free reaction energy (15 kcal mol−1 and −40 kcal mol−1) show that this hydride step takes place with the involvement of a cationic His405 and Lys639, and a neutral Glu98, while Asp715 remains in an anionic state. The results provide an atomic-level portrait of this step, clearly demonstrating the nature and protonation state of the amino acid residues involved, the energetics associated, and the structure and charge of the key participating atoms in the several intermediate states, finally elucidating this missing step.

scholarly journals New CHARMM force field parameters for dehydrated amino acid residues, the key to lantibiotic molecular dynamics simulations

RSC Advances ◽  
2014 ◽  
Vol 4 (89) ◽  
pp. 48621-48631 ◽  
Author(s):  
Eleanor R. Turpin ◽  
Sam Mulholland ◽  
Andrew M. Teale ◽  
Boyan B. Bonev ◽  
Jonathan D. Hirst
Keyword(s):  
Molecular Dynamics ◽  
Amino Acid ◽  
Force Field ◽  
Molecular Dynamics Simulations ◽  
Amino Acid Residues ◽  
Charmm Force Field ◽  
Force Field Parameters ◽  
Dynamics Simulations

Visualising intrinsic disorder and conformational variation in protein ensembles

2014 ◽  
Vol 169 ◽  
pp. 179-193 ◽  
Author(s):  
Julian Heinrich ◽  
Michael Krone ◽  
Seán I. O'Donoghue ◽  
Daniel Weiskopf
Keyword(s):  
Intrinsic Disorder ◽  
Molecular Graphics ◽  
Post Translational Modifications ◽  
3D Structures ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Wide Range ◽  
Conformational Variations ◽  
Protein Ensembles ◽  
Traditional Approaches

Intrinsically disordered regions (IDRs) in proteins are still not well understood, but are increasingly recognised as important in key biological functions, as well as in diseases. IDRs often confound experimental structure determination—however, they are present in many of the available 3D structures, where they exhibit a wide range of conformations, from ill-defined and highly flexible to well-defined upon binding to partner molecules, or upon post-translational modifications. Analysing such large conformational variations across ensembles of 3D structures can be complex and difficult; our goal in this paper is to improve this situation by augmenting traditional approaches (molecular graphics and principal components) with methods from human–computer interaction and information visualisation, especially parallel coordinates. We present a new tool integrating these approaches, and demonstrate how it can dissect ensembles to reveal functional insights into conformational variation and intrinsic disorder.

scholarly journals Molecular dynamics shows complex interplay and long-range effects of post-translational modifications in yeast protein interactions

2021 ◽  
Vol 17 (5) ◽  
pp. e1008988
Author(s):  
Nikolina ŠoŠtarić ◽  
Vera van Noort
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Protein Structures ◽  
Cellular Protein ◽  
Free Energy Calculations ◽  
Protein Protein Interactions ◽  
Post Translational Modifications ◽  
Protein Properties ◽  
Dynamics Simulations

Post-translational modifications (PTMs) play a vital, yet often overlooked role in the living cells through modulation of protein properties, such as localization and affinity towards their interactors, thereby enabling quick adaptation to changing environmental conditions. We have previously benchmarked a computational framework for the prediction of PTMs’ effects on the stability of protein-protein interactions, which has molecular dynamics simulations followed by free energy calculations at its core. In the present work, we apply this framework to publicly available data on Saccharomyces cerevisiae protein structures and PTM sites, identified in both normal and stress conditions. We predict proteome-wide effects of acetylations and phosphorylations on protein-protein interactions and find that acetylations more frequently have locally stabilizing roles in protein interactions, while the opposite is true for phosphorylations. However, the overall impact of PTMs on protein-protein interactions is more complex than a simple sum of local changes caused by the introduction of PTMs and adds to our understanding of PTM cross-talk. We further use the obtained data to calculate the conformational changes brought about by PTMs. Finally, conservation of the analyzed PTM residues in orthologues shows that some predictions for yeast proteins will be mirrored to other organisms, including human. This work, therefore, contributes to our overall understanding of the modulation of the cellular protein interaction networks in yeast and beyond.

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.

Translocation intermediates of ubiquitin through an α-hemolysin nanopore: implications for detection of post-translational modifications

Nanoscale ◽  
2019 ◽  
Vol 11 (20) ◽  
pp. 9920-9930 ◽  
Author(s):  
Emma Letizia Bonome ◽  
Fabio Cecconi ◽  
Mauro Chinappi
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Post Translational Modifications ◽  
Dynamics Simulations

Molecular dynamics simulations allowed to characterize the co-translocational unfolding pathway of ubiquitin through a biological nanopore.

scholarly journals SLC6A14, a Pivotal Actor on Cancer Stage: When Function Meets Structure

2019 ◽  
Vol 24 (9) ◽  
pp. 928-938 ◽  
Author(s):  
Luca Palazzolo ◽  
Chiara Paravicini ◽  
Tommaso Laurenzi ◽  
Sara Adobati ◽  
Simona Saporiti ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Amino Acids ◽  
Amino Acid ◽  
Molecular Dynamics Simulations ◽  
Electrostatic Interactions ◽  
Amino Acid Residues ◽  
Dibasic Amino Acid ◽  
Novel Target ◽  
Function Relationship ◽  
Dynamics Simulations

SLC6A14 (ATB0,+) is a sodium- and chloride-dependent neutral and dibasic amino acid transporter that regulates the distribution of amino acids across cell membranes. The transporter is overexpressed in many human cancers characterized by an increased demand for amino acids; as such, it was recently acknowledged as a novel target for cancer therapy. The knowledge on the molecular mechanism of SLC6A14 transport is still limited, but some elegant studies on related transporters report the involvement of the 12 transmembrane α-helices in the transport mechanism, and describe structural rearrangements mediated by electrostatic interactions with some pivotal gating residues. In the present work, we constructed a SLC6A14 model in outward-facing conformation via homology modeling and used molecular dynamics simulations to predict amino acid residues critical for substrate recognition and translocation. We docked the proteinogenic amino acids and other known substrates in the SLC6A14 binding site to study both gating regions and the exposed residues involved in transport. Interestingly, some of these residues correspond to those previously identified in other LeuT-fold transporters; however, we could also identify a novel relevant residue with such function. For the first time, by combined approaches of molecular docking and molecular dynamics simulations, we highlight the potential role of these residues in neutral amino acid transport. This novel information unravels new aspects of the human SLC6A14 structure–function relationship and may have important outcomes for cancer treatment through the design of novel inhibitors of SLC6A14-mediated transport.

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