Conformational Changes of Glutamine 5′-Phosphoribosylpyrophosphate Amidotransferase for Two Substrates Analogue Binding: Insight from Conventional Molecular Dynamics and Accelerated Molecular Dynamics Simulations

Glutamine 5′-phosphoribosylpyrophosphate amidotransferase (GPATase) catalyzes the synthesis of phosphoribosylamine, pyrophosphate, and glutamate from phosphoribosylpyrophosphate, as well as glutamine at two sites (i.e., glutaminase and phosphoribosylpyrophosphate sites), through a 20 Å NH3 channel. In this study, conventional molecular dynamics (cMD) simulations and enhanced sampling accelerated molecular dynamics (aMD) simulations were integrated to characterize the mechanism for coordination catalysis at two separate active sites in the enzyme. Results of cMD simulations illustrated the mechanism by which two substrate analogues, namely, DON and cPRPP, affect the structural stability of GPATase from the perspective of dynamic behavior. aMD simulations obtained several key findings. First, a comparison of protein conformational changes in the complexes of GPATase–DON and GPATase–DON–cPRPP showed that binding cPRPP to the PRTase flexible loop (K326 to L350) substantially effected the formation of the R73-DON salt bridge. Moreover, only the PRTase flexible loop in the GPATase–DON–cPRPP complex could remain closed and had sufficient space for cPRPP binding, indicating that binding of DON to the glutamine loop had an impact on the PRTase flexible loop. Finally, both DON and cPRPP tightly bonded to the two domains, thereby inducing the glutamine loop and the PRTase flexible loop to move close to each other. This movement facilitated the transfer of NH3 via the NH3 channel. These theoretical results are useful to the ongoing research on efficient inhibitors related to GPATase.

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Accelerated Molecular Dynamics Applied to the Peptaibol Folding Problem

International Journal of Molecular Sciences ◽

10.3390/ijms20174268 ◽

2019 ◽

Vol 20 (17) ◽

pp. 4268

Author(s):

Chetna Tyagi ◽

Tamás Marik ◽

Csaba Vágvölgyi ◽

László Kredics ◽

Ferenc Ötvös

Keyword(s):

Molecular Dynamics ◽

Enhanced Sampling ◽

New Approach ◽

E Coli ◽

Accelerated Molecular Dynamics ◽

Simulation Techniques ◽

Unfolded State ◽

Folding Dynamics ◽

Transmembrane Channels ◽

Dynamics Simulations

The use of enhanced sampling molecular dynamics simulations to facilitate the folding of proteins is a relatively new approach which has quickly gained momentum in recent years. Accelerated molecular dynamics (aMD) can elucidate the dynamic path from the unfolded state to the near-native state, “flattened” by introducing a non-negative boost to the potential. Alamethicin F30/3 (Alm F30/3), chosen in this study, belongs to the class of peptaibols that are 7–20 residue long, non-ribosomally synthesized, amphipathic molecules that show interesting membrane perturbing activity. The recent studies undertaken on the Alm molecules and their transmembrane channels have been reviewed. Three consecutive simulations of ~900 ns each were carried out where N-terminal folding could be observed within the first 100 ns, while C-terminal folding could only be achieved almost after 800 ns. It took ~1 μs to attain the near-native conformation with stronger potential boost which may take several μs worth of classical MD to produce the same results. The Alm F30/3 hexamer channel was also simulated in an E. coli mimicking membrane under an external electric field that correlates with previous experiments. It can be concluded that aMD simulation techniques are suited to elucidate peptaibol structures and to understand their folding dynamics.

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How well do force fields capture the strength of salt bridges in proteins?

10.1101/272799 ◽

2018 ◽

Author(s):

Mustapha Carab Ahmed ◽

Elena Papaleo ◽

Kresten Lindorff-Larsen

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Force Fields ◽

Salt Bridge ◽

Salt Bridges ◽

Enhanced Sampling ◽

Important Interaction ◽

Close Proximity ◽

The Stability ◽

Dynamics Simulations

AbstractSalt bridges form between pairs of ionisable residues in close proximity and are important interactions in proteins. While salt bridges are known to be important both for protein stability, recognition and regulation, we still do not have fully accurate predictive models to assess the energetic contributions of salt bridges. Molecular dynamics simulations is one technique that may be used study the complex relationship between structure, solvation and energetics of salt bridges, but the accuracy of such simulations depend on the force field used. We have used NMR data on the B1 domain of protein G (GB1) to benchmark molecular dynamics simulations. Using enhanced sampling simulations, we calculated the free energy of forming a salt bridge for three possible ionic interactions in GB1. The NMR experiments showed that these interactions are either not formed, or only very weakly formed, in solution. In contrast, we show that the stability of the salt bridges is slightly overestimated in simulations of GB1 using six commonly used combinations of force fields and water models. We therefore conclude that further work is needed to refine our ability to model quantitatively the stability of salt bridges through simulations, and that comparisons between experiments and simulations will play a crucial role in furthering our understanding of this important interaction.

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Salt bridges gate α-catenin activation at intercellular junctions

Molecular Biology of the Cell ◽

10.1091/mbc.e17-03-0168 ◽

2018 ◽

Vol 29 (2) ◽

pp. 111-122 ◽

Cited By ~ 10

Author(s):

Samantha Barrick ◽

Jing Li ◽

Xinyu Kong ◽

Alokananda Ray ◽

Emad Tajkhorshid ◽

...

Keyword(s):

Molecular Dynamics ◽

Mechanical Activation ◽

Conformational Changes ◽

Intercellular Junctions ◽

Salt Bridge ◽

Salt Bridges ◽

Equilibrium Binding ◽

Binding Data ◽

Dynamics Simulations ◽

Intercellular Adhesions

Molecular dynamics simulations, equilibrium binding measurements, and fluorescence imaging reveal the influence of a key salt bridge in the mechanical activation of α-catenin at intercellular adhesions. Simulations reveal possible α-catenin conformational changes underlying experimental fluorescence and equilibrium binding data.

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Enhanced Sampling of Peptide Binding to Proteins through Gaussian Accelerated Molecular Dynamics Simulations

Biophysical Journal ◽

10.1016/j.bpj.2019.11.887 ◽

2020 ◽

Vol 118 (3) ◽

pp. 139a

Author(s):

Jinan Wang ◽

Andrey Alekseenko ◽

Dima Kozakov ◽

Yinglong Miao

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Peptide Binding ◽

Enhanced Sampling ◽

Accelerated Molecular Dynamics ◽

Dynamics Simulations

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Ion Pairing and Dielectric Decrement in Glycosaminoglycan Brushes

10.26434/chemrxiv.13501698.v1 ◽

2020 ◽

Author(s):

James Sterling ◽

Wenjuan Jiang ◽

Wesley M. Botello-Smith ◽

Yun L. Luo

Keyword(s):

Molecular Dynamics ◽

Ion Pairs ◽

Mean Field ◽

Salt Bridge ◽

Ion Pairing ◽

Donnan Potential ◽

Mean Field Models ◽

Ion Exclusion ◽

Dynamics Simulations ◽

Contact Ion Pairs

Molecular dynamics simulations of hyaluronic acid and heparin brushes are presented that show important effects of ion-pairing, water dielectric decrease, and co-ion exclusion. Results show equilibria with electroneutrality attained through screening and pairing of brush anionic charges by cations. Most surprising is the reversal of the Donnan potential that would be expected based on electrostatic Boltzmann partitioning alone. Water dielectric decrement within the brush domain is also associated with Born hydration-driven cation exclusion from the brush. We observe that the primary partition energy attracting cations to attain brush electroneutrality is the ion-pairing or salt-bridge energy associated with cation-sulfate and cation-carboxylate solvent-separated and contact ion pairs. Potassium and sodium pairing to glycosaminoglycan carboxylates and sulfates consistently show similar abundance of contact-pairing and solvent-separated pairing. In these crowded macromolecular brushes, ion-pairing, Born-hydration, and electrostatic potential energies all contribute to attain electroneutrality and should therefore contribute in mean-field models to accurately represent brush electrostatics.

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Molecular Basis of Glucose Transport Mechanism in Plants

10.26434/chemrxiv.8049848.v1 ◽

2019 ◽

Cited By ~ 2

Author(s):

Balaji Selvam ◽

Ya-Chi Yu ◽

Liqing Chen ◽

Diwakar Shukla

Keyword(s):

Molecular Dynamics ◽

Free Energy ◽

Molecular Dynamics Simulations ◽

Conformational Changes ◽

Transport Mechanism ◽

Conformational Dynamics ◽

Site Directed Mutagenesis ◽

Free Energy Barrier ◽

Transport Cycle ◽

Dynamics Simulations

<p>The SWEET family belongs to a class of transporters in plants that undergoes large conformational changes to facilitate transport of sugar molecules across the cell membrane. However, the structures of their functionally relevant conformational states in the transport cycle have not been reported. In this study, we have characterized the conformational dynamics and complete transport cycle of glucose in OsSWEET2b transporter using extensive molecular dynamics simulations. Using Markov state models, we estimated the free energy barrier associated with different states as well as 1 for the glucose the transport mechanism. SWEETs undergoes structural transition to outward-facing (OF), Occluded (OC) and inward-facing (IF) and strongly support alternate access transport mechanism. The glucose diffuses freely from outside to inside the cell without causing major conformational changes which means that the conformations of glucose unbound and bound snapshots are exactly same for OF, OC and IF states. We identified a network of hydrophobic core residues at the center of the transporter that restricts the glucose entry to the cytoplasmic side and act as an intracellular hydrophobic gate. The mechanistic predictions from molecular dynamics simulations are validated using site-directed mutagenesis experiments. Our simulation also revealed hourglass like intermediate states making the pore radius narrower at the center. This work provides new fundamental insights into how substrate-transporter interactions actively change the free energy landscape of the transport cycle to facilitate enhanced transport activity.</p>

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Molecular mechanism concerning conformational changes of CDK2 mediated by binding of inhibitors using molecular dynamics simulations and principal component analysis

SAR and QSAR in Environmental Research ◽

10.1080/1062936x.2021.1934896 ◽

2021 ◽

pp. 1-22

Author(s):

S.S. Liang ◽

X.G. Liu ◽

Y.X. Cui ◽

S.L. Zhang ◽

Q.G. Zhang ◽

...

Keyword(s):

Molecular Dynamics ◽

Principal Component Analysis ◽

Molecular Dynamics Simulations ◽

Molecular Mechanism ◽

Conformational Changes ◽

Principal Component ◽

Component Analysis ◽

Dynamics Simulations

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Studies of Conformational Changes of Tubulin Induced by Interaction with Kinesin Using Atomistic Molecular Dynamics Simulations

International Journal of Molecular Sciences ◽

10.3390/ijms22136709 ◽

2021 ◽

Vol 22 (13) ◽

pp. 6709

Author(s):

Xiao-Xuan Shi ◽

Peng-Ye Wang ◽

Hong Chen ◽

Ping Xie

Keyword(s):

Molecular Dynamics ◽

High Resolution ◽

Binding Energy ◽

Molecular Dynamics Simulations ◽

Conformational Changes ◽

Weak Interactions ◽

Molecular Motor ◽

Structural Data ◽

Calculated Binding Energy ◽

Dynamics Simulations

The transition between strong and weak interactions of the kinesin head with the microtubule, which is regulated by the change of the nucleotide state of the head, is indispensable for the processive motion of the kinesin molecular motor on the microtubule. Here, using all-atom molecular dynamics simulations, the interactions between the kinesin head and tubulin are studied on the basis of the available high-resolution structural data. We found that the strong interaction can induce rapid large conformational changes of the tubulin, whereas the weak interaction cannot. Furthermore, we found that the large conformational changes of the tubulin have a significant effect on the interaction of the tubulin with the head in the weak-microtubule-binding ADP state. The calculated binding energy of the ADP-bound head to the tubulin with the large conformational changes is only about half that of the tubulin without the conformational changes.

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