Influence of the R823W mutation on the interaction of the ANKS6–ANKS3: insights from molecular dynamics simulation and free energy analysis

<p>The sterile alpha motif (SAM) domain of the protein ANKS6, a protein–protein interaction domain, is responsible for autosomal dominant polycystic kidney disease. Although the disease is the result of the R823W point mutation in the SAM domain of the protein ANKS6, the molecular details are still unclear. We applied molecular dynamics simulations, the principal component analysis, and the molecular mechanics Poisson–Boltzmann surface area binding free energy calculation to explore the structural and dynamic effects of the R823W point mutation on the complex ANKS6–ANKS3 (PDB ID: 4NL9) in comparison to the wild proteins. The energetic analysis presents that the wild type has a more stable structure than the mutant. The R823W point mutation not only disrupts the structure of the ANKS6 SAM domain but also negatively affects the interaction of the ANKS6–ANKS3. These results further clarify the previous experiments to understand the ANKS6–ANKS3 interaction comprehensively. In summary, this study would provide useful suggestions to understand the interaction of these proteins and their fatal action on mediating kidney function.</p

Thermal stability and unfolding pathways of hyperthermophilic and mesophilic periplasmic binding proteins studied by molecular dynamics simulation

<p>The ribose binding protein (RBP), a sugar-binding periplasmic protein, is involved in the transport and signaling processes in both prokaryotes and eukaryotes. Although several cellular and structural studies have been reported, a description of the thermostability of RBP at the molecular level remains elusive. Focused on the hyperthermophilic <i>Thermoytoga maritima</i> RBP (tmRBP) and mesophilic <i>Escherichia coli</i> homolog (ecRBP), we applied molecular dynamics simulations at four different temperatures (300, 380, 450, and 500 K) to obtain a deeper insight into the structural features responsible for the reduced thermostability of the ecRBP. The simulations results indicate that there are distinct structural differences in the unfolding pathway between the two homologs and the ecRBP unfolds faster than the hyperthermophilic homologs at certain temperatures in accordance with the lower thermal stability found experimentally. Essential dynamics analysis uncovers that the essential subspaces of ecRBP and tmRBP are non-overlapping and these two proteins show different directions of motion within the simulations trajectories. Such an understanding is required for designing efficient proteins with characteristics for a particular application.</p