Using molecular simulation to explore the nanoscale dynamics of the plant kinome

2018 ◽  
Vol 475 (5) ◽  
pp. 905-921 ◽  
Author(s):  
Alexander S. Moffett ◽  
Diwakar Shukla

Eukaryotic protein kinases (PKs) are a large family of proteins critical for cellular response to external signals, acting as molecular switches. PKs propagate biochemical signals by catalyzing phosphorylation of other proteins, including other PKs, which can undergo conformational changes upon phosphorylation and catalyze further phosphorylations. Although PKs have been studied thoroughly across the domains of life, the structures of these proteins are sparsely understood in numerous groups of organisms, including plants. In addition to efforts towards determining crystal structures of PKs, research on human PKs has incorporated molecular dynamics (MD) simulations to study the conformational dynamics underlying the switching of PK function. This approach of experimental structural biology coupled with computational biophysics has led to improved understanding of how PKs become catalytically active and why mutations cause pathological PK behavior, at spatial and temporal resolutions inaccessible to current experimental methods alone. In this review, we argue for the value of applying MD simulation to plant PKs. We review the basics of MD simulation methodology, the successes achieved through MD simulation in animal PKs, and current work on plant PKs using MD simulation. We conclude with a discussion of the future of MD simulations and plant PKs, arguing for the importance of molecular simulation in the future of plant PK research.

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mac Kevin E. Braza ◽  
Jerrica Dominique N. Gazmen ◽  
Eizadora T. Yu ◽  
Ricky B. Nellas

Abstract Tyramine receptor (TyrR) is a biogenic amine G protein-coupled receptor (GPCR) associated with many important physiological functions in insect locomotion, reproduction, and pheromone response. Binding of specific ligands to the TyrR triggers conformational changes, relays the signal to G proteins, and initiates an appropriate cellular response. Here, we monitor the binding effect of agonist compounds, tyramine and amitraz, to a Sitophilus oryzae tyramine receptor (SoTyrR) homology model and their elicited conformational changes. All-atom molecular dynamics (MD) simulations of SoTyrR-ligand complexes have shown varying dynamic behavior, especially at the intracellular loop 3 (IL3) region. Moreover, in contrast to SoTyrR-tyramine, SoTyrR-amitraz and non-liganded SoTyrR shows greater flexibility at IL3 residues and were found to be coupled to the most dominant motion in the receptor. Our results suggest that the conformational changes induced by amitraz are different from the natural ligand tyramine, albeit being both agonists of SoTyrR. This is the first attempt to understand the biophysical implication of amitraz and tyramine binding to the intracellular domains of TyrR. Our data may provide insights into the early effects of ligand binding to the activation process of SoTyrR.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Raghavendar Reddy Sanganna Gari ◽  
Joel José Montalvo‐Acosta ◽  
George R. Heath ◽  
Yining Jiang ◽  
Xiaolong Gao ◽  
...  

AbstractConformational changes in ion channels lead to gating of an ion-conductive pore. Ion flux has been measured with high temporal resolution by single-channel electrophysiology for decades. However, correlation between functional and conformational dynamics remained difficult, lacking experimental techniques to monitor sub-millisecond conformational changes. Here, we use the outer membrane protein G (OmpG) as a model system where loop-6 opens and closes the β-barrel pore like a lid in a pH-dependent manner. Functionally, single-channel electrophysiology shows that while closed states are favored at acidic pH and open states are favored at physiological pH, both states coexist and rapidly interchange in all conditions. Using HS-AFM height spectroscopy (HS-AFM-HS), we monitor sub-millisecond loop-6 conformational dynamics, and compare them to the functional dynamics from single-channel recordings, while MD simulations provide atomistic details and energy landscapes of the pH-dependent loop-6 fluctuations. HS-AFM-HS offers new opportunities to analyze conformational dynamics at timescales of domain and loop fluctuations.


2020 ◽  
Vol 117 (34) ◽  
pp. 20597-20606 ◽  
Author(s):  
Olivier Fisette ◽  
Gunnar F. Schröder ◽  
Lars V. Schäfer

The major histocompatibility complex class-I (MHC-I) peptide-loading complex (PLC) is a cornerstone of the human adaptive immune system, being responsible for processing antigens that allow killer T cells to distinguish between healthy and compromised cells. Based on a recent low-resolution cryo-electron microscopy (cryo-EM) structure of this large membrane-bound protein complex, we report an atomistic model of the PLC and study its conformational dynamics on the multimicrosecond time scale using all-atom molecular dynamics (MD) simulations in an explicit lipid bilayer and water environment (1.6 million atoms in total). The PLC has a layered structure, with two editing modules forming a flexible protein belt surrounding a stable, catalytically active core. Tapasin plays a central role in the PLC, stabilizing the MHC-I binding groove in a conformation reminiscent of antigen-loaded MHC-I. The MHC-I–linked glycan steers a tapasin loop involved in peptide editing toward the binding groove. Tapasin conformational dynamics are also affected by calreticulin through a conformational selection mechanism that facilitates MHC-I recruitment into the complex.


2020 ◽  
Author(s):  
Yangang Pan ◽  
Luda S. Shlyakhtenko ◽  
Yuri L. Lyubchenko

AbstractViral infectivity factor (Vif) is a protein that is essential for the replication of the HIV-1 virus. The key function of Vif is to disrupt the antiviral activity of APOBEC3 proteins, which mutate viral nucleic acids. Inside the cell, Vif binds to the host cell proteins Elongin-C, Elongin-B, and CBF-β, forming a four-protein complex called VCBC. The structure of VCBC in complex with the Cullin5 (Cul5) protein has been solved by X-ray crystallography, and recently, using molecular dynamic (MD) simulations, the dynamics of VCBC and VCBC-Cul5 complexes were characterized. Here, we applied time-lapse high-speed atomic force microscopy (HS-AFM) to visualize the conformational changes of the VCBC complex. We determined the three most favorable conformations of the VCBC complex, which we identified as triangle, dumbbell, and globular structures. In addition, we characterized the dynamics of each of these structures. While our data show a very dynamic behavior for all these structures, we found the triangle and dumbbell structures to be the most dynamic. These findings provide insight into the structure and dynamics of the VCBC complex and support further research into the improvement of HIV treatment, as Vif is essential for virus survival in the cell.


2021 ◽  
Author(s):  
Pritam Biswas ◽  
Uttam Pal ◽  
Aniruddha Adhikari ◽  
Susmita Mondal ◽  
Ria Ghosh ◽  
...  

Conformational dynamics of macromolecules including enzymes are essential for their function. The present work reports the role of essential dynamics in alpha-chymotrypsin (CHT) which correlates with its catalytic activity. Detailed optical spectroscopy and classical molecular dynamics (MD) simulation were used to study thermal stability, catalytic activity and dynamical flexibility of the enzyme. The study of the enzyme kinetics reveals an optimum catalytic efficiency at 308K. Polarization gated fluorescence anisotropy with 8-anilino-1-napthelene sulfonate (ANS) have indicated increasing flexibility of the enzyme with an increase in temperature. Examination of the structure of CHT reveal the presence of five loop regions (LRs) around the catalytic S1 pocket. MD simulations have indicated that flexibility increases concurrently with temperature which decreases beyond optimum temperature. Principal component analysis (PCA) of the eigenvectors manifests essential dynamics and gatekeeping role of the five LRs surrounding the catalytic pocket which controls the enzyme activity.


2019 ◽  
Author(s):  
Dylan Ogden ◽  
Kalyan Immadisetty ◽  
Mahmoud Moradi

AbstractMajor facilitator superfamily (MFS) of transporters consists of three classes of membrane transporters: symporters, uniporters, and antiporters. Despite such diverse functions, MFS transporters are believed to undergo similar conformational changes within their distinct transport cycles. While the similarities between conformational changes are noteworthy, the differences are also important since they could potentially explain the distinct functions of symporters, uniporters, and antiporters of MFS superfamily. We have performed a variety of equilibrium, non-equilibrium, biased, and unbiased all-atom molecular dynamics (MD) simulations of bacterial proton-coupled oligopeptide transporter GkPOT, glucose transporter 1 (GluT1), and glycerol-3-phosphate transporter (GlpT) to compare the similarities and differences of the conformational dynamics of three different classes of transporters. Here we have simulated the apo protein in an explicit membrane environment. Our results suggest a very similar conformational transition involving interbundle salt-bridge formation/disruption coupled with the orientation changes of transmembrane (TM) helices, specifically H1/H7 and H5/H11, resulting in an alternation in the accessibility of water at the cyto- and periplasmic gates.


2018 ◽  
Author(s):  
Ken Ellis-Guardiola ◽  
Huan Rui ◽  
Ryan Beckner ◽  
Poonam Srivastava ◽  
Narayanasami Sukumar ◽  
...  

Supramolecular catalysis involves the design and characterization of synthetic macromolecules that catalyze chemical reactions. While enzymes are often cited as the inspiration for such catalysts, enzymes can also serve as hosts for non-native catalytic components. Protein-based hosts can be readily produced in E. coli and rapidly evolved for particular applications. Moreover, inherent properties of these systems, including their conformational dynamics, can be exploited for non-native transformations that occur within their interior. Studies on the peptidase activity of a prolyl oligopeptidase from Pyrococcus furiosus (Pfu POP) suggest that its unique two-domain architecture regulates substrate access and specificity. We have established that Pfu POP also serves as an efficient host for asymmetric cyclopropanation upon active-site modification with a dirhodium cofactor. To understand how Pfu POP controls both peptidase and dirhodium catalysis, we determined the crystal structures of this enzyme and its S477C mutant and used these structures as starting points for MD simulations of both the apo structures and systems containing a covalently linked peptidase inhibitor or a dirhodium catalyst. Pfu POP was crystalized in an open conformation, and MD simulations reveal spontaneous transitions between open and closed states, in addition to a number of smaller scale conformational changes, suggesting facile inter-domain movement. Importantly, key aspects of previously reported peptidase kinetics and cyclopropanation selectivity can be rationalized in the context of this inter-domain opening and closing. This finding constitutes a remarkable example in which the conformational dynamics of a supramolecular host affect two different catalytic activities and suggests that Pfu POP could serve as a host for a wide range of non-native catalysts.


2018 ◽  
Author(s):  
D. R. Kattnig ◽  
C. Nielsen ◽  
I. A. Solov’yov

AbstractBirds appear to be equipped with a light-dependent, radical-pair-based magnetic compass that relies on truly quantum processes. While the identity of the sensory protein has remained speculative, cryptochrome 4 has recently been identified as the most auspicious candidate. Here, we report on allatom molecular dynamics (MD) simulations addressing the structural reorganisations that accompany the photoreduction of the flavin cofactor in a model of the European robin cryptochrome 4 (ErCry4). Extensive MD simulations reveal that the photo-activation of ErCry4 induces large-scale conformational changes on short (hundreds of nanoseconds) timescales. Specifically, the photo-reduction is accompanied with the release of the C-terminal tail, structural rearrangements in the vicinity of the FAD-binding site, and the noteworthy formation of an α-helical segment at the N-terminal part. Some of these rearrangements appear to expose potential phosphorylation sites. We describe the conformational dynamics of the protein using a graph-based approach that is informed by the adjacency of residues and the correlation of their local motions. This approach reveals densely coupled reorganisation communities, which facilitate an efficient signal transduction due to a high density of hubs. These communities are interconnected by a small number of highly important residues characterized by high betweenness centrality. The network approach clearly identifies the sites restructuring upon photoactivation, which appear as protrusions or delicate bridges in the reorganisation network. We also find that, unlike in the homologous cryptochrome from D. melanogaster, the release of the C-terminal domain does not appear to be correlated with the transposition of a histidine residue close to the FAD cofactor.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruyu Jia ◽  
Chloe Martens ◽  
Mrinal Shekhar ◽  
Shashank Pant ◽  
Grant A. Pellowe ◽  
...  

AbstractProton-coupled transporters use transmembrane proton gradients to power active transport of nutrients inside the cell. High-resolution structures often fail to capture the coupling between proton and ligand binding, and conformational changes associated with transport. We combine HDX-MS with mutagenesis and MD simulations to dissect the molecular mechanism of the prototypical transporter XylE. We show that protonation of a conserved aspartate triggers conformational transition from outward-facing to inward-facing state. This transition only occurs in the presence of substrate xylose, while the inhibitor glucose locks the transporter in the outward-facing state. MD simulations corroborate the experiments by showing that only the combination of protonation and xylose binding, and not glucose, sets up the transporter for conformational switch. Overall, we demonstrate the unique ability of HDX-MS to distinguish between the conformational dynamics of inhibitor and substrate binding, and show that a specific allosteric coupling between substrate binding and protonation is a key step to initiate transport.


Author(s):  
Ken Ellis-Guardiola ◽  
Huan Rui ◽  
Ryan Beckner ◽  
Poonam Srivastava ◽  
Narayanasami Sukumar ◽  
...  

Supramolecular catalysis involves the design and characterization of synthetic macromolecules that catalyze chemical reactions. While enzymes are often cited as the inspiration for such catalysts, enzymes can also serve as hosts for non-native catalytic components. Protein-based hosts can be readily produced in E. coli and rapidly evolved for particular applications. Moreover, inherent properties of these systems, including their conformational dynamics, can be exploited for non-native transformations that occur within their interior. Studies on the peptidase activity of a prolyl oligopeptidase from Pyrococcus furiosus (Pfu POP) suggest that its unique two-domain architecture regulates substrate access and specificity. We have established that Pfu POP also serves as an efficient host for asymmetric cyclopropanation upon active-site modification with a dirhodium cofactor. To understand how Pfu POP controls both peptidase and dirhodium catalysis, we determined the crystal structures of this enzyme and its S477C mutant and used these structures as starting points for MD simulations of both the apo structures and systems containing a covalently linked peptidase inhibitor or a dirhodium catalyst. Pfu POP was crystalized in an open conformation, and MD simulations reveal spontaneous transitions between open and closed states, in addition to a number of smaller scale conformational changes, suggesting facile inter-domain movement. Importantly, key aspects of previously reported peptidase kinetics and cyclopropanation selectivity can be rationalized in the context of this inter-domain opening and closing. This finding constitutes a remarkable example in which the conformational dynamics of a supramolecular host affect two different catalytic activities and suggests that Pfu POP could serve as a host for a wide range of non-native catalysts.


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