scholarly journals Increasing the thermostability of the neutral proteinase of Bacillus stearothermophilus by improvement of internal hydrogen-bonding

1992 ◽  
Vol 285 (2) ◽  
pp. 625-628 ◽  
Author(s):  
V G Eijsink ◽  
G Vriend ◽  
J R Van der Zee ◽  
B Van den Burg ◽  
G Venema
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Bacillus Stearothermophilus ◽  
Site Directed Mutagenesis ◽  
Internal Cavity ◽  
Directed Mutagenesis ◽  
Neutral Proteinase ◽  
Internal Hydrogen ◽  
Internal Hydrogen Bond ◽  
Dynamics Simulations

In an attempt to increase the thermostability of the neutral proteinase of Bacillus stearothermophilus the buried Ala-170 was replaced by serine. Molecular-dynamics simulations showed that Ser-170 stabilizes the enzyme by formation of an internal hydrogen bond. In addition, the hydroxy group of Ser-170 could contribute to stability by filling an internal cavity. After the introduction of the mutation, using site-directed-mutagenesis techniques, an increase in stability of 0.7 +/- 0.1 degrees C was obtained.

scholarly journals The first crystal structure of human RNase 6 reveals a novel substrate-binding and cleavage site arrangement

2016 ◽  
Vol 473 (11) ◽  
pp. 1523-1536 ◽  
Author(s):  
Guillem Prats-Ejarque ◽  
Javier Arranz-Trullén ◽  
Jose A. Blanco ◽  
David Pulido ◽  
M. Victòria Nogués ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Kinetic Analysis ◽  
Cleavage Site ◽  
Substrate Recognition ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Cleavage Sites ◽  
Human Rnase ◽  
Dynamics Simulations

We describe the first human RNase 6 crystal structure in complex with sulfate anions. Kinetic analysis, site-directed mutagenesis and molecular dynamics simulations identified novel substrate recognition and cleavage sites.

scholarly journals Identification of key binding site residues of MCT1 for AR-C155858 reveals the molecular basis of its isoform selectivity

2015 ◽  
Vol 466 (1) ◽  
pp. 177-188 ◽  
Author(s):  
Bethany Nancolas ◽  
Richard B. Sessions ◽  
Andrew P. Halestrap
Keyword(s):  
Molecular Dynamics ◽  
Amino Acids ◽  
Binding Site ◽  
Molecular Basis ◽  
Specific Inhibitor ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Isoform Specificity ◽  
Isoform Selectivity ◽  
Dynamics Simulations

A combination of molecular modelling, site-directed mutagenesis and molecular dynamics simulations define the binding site of MCT1 for AR-C155858, a potent and specific inhibitor. Key amino acids within the binding site differ between MCT1 and MCT4 accounting for isoform specificity.

scholarly journals Pressure Adaptations in Deep-Sea Moritella Dihydrofolate Reductases: Compressibility versus Stability

Biology ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1211
Author(s):  
Ryan W. Penhallurick ◽  
Toshiko Ichiye
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Dihydrofolate Reductase ◽  
Deep Sea ◽  
Water Entry ◽  
Internal Cavity ◽  
Cavity Volume ◽  
Dihydrofolate Reductases ◽  
Moritella Profunda ◽  
Dynamics Simulations

Proteins from “pressure-loving” piezophiles appear to adapt by greater compressibility via larger total cavity volume. However, larger cavities in proteins have been associated with lower unfolding pressures. Here, dihydrofolate reductase (DHFR) from a moderate piezophile Moritella profunda (Mp) isolated at ~2.9 km in depth and from a hyperpiezophile Moritella yayanosii (My) isolated at ~11 km in depth were compared using molecular dynamics simulations. Although previous simulations indicate that MpDHFR is more compressible than a mesophile DHFR, here the average properties and a quasiharmonic analysis indicate that MpDHFR and MyDHFR have similar compressibilities. A cavity analysis also indicates that the three unique mutations in MyDHFR are near cavities, although the cavities are generally similar in size in both. However, while a cleft overlaps an internal cavity, thus forming a pathway from the surface to the interior in MpDHFR, the unique residue Tyr103 found in MyDHFR forms a hydrogen bond with Leu78, and the sidechain separates the cleft from the cavity. Thus, while Moritella DHFR may generally be well suited to high-pressure environments because of their greater compressibility, adaptation for greater depths may be to prevent water entry into the interior cavities.

Molecular Basis of Glucose Transport Mechanism in Plants

2019 ◽  
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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