Effects of protein-DNA complex formation on the intermolecular vibrational density of states of interfacial water

Base pair compositional variability influences DNA structural stability and tunes hydration thermodynamics and dynamics

DNA deformability and differential hydration are crucial determinants of biological processes ranging from genetic material packaging to gene expression; their associative details, however, remain inadequately understood. Herein, we report investigations of the dynamic and thermodynamic responses of the local hydration of a variety of base pair sequences. Leveraging in silico sampling and our in-house analyses, we first report the local conformational propensity of sequences that are either predisposed toward the canonical A- or B-conformations or are restrained to potential transitory pathways. It is observed that the transition from the unrestrained A-form to the B-form leads to lengthwise structural deformation. The insertion of intermittent -(CG)- base pairs in otherwise homogeneous -(AT)- sequences bears dynamical consequences for the vicinal hydration layer. Calculation of the excess (pair) entropy suggests substantially higher values of hydration water surrounding A conformations over the B- conformations. Applying the Rosenfeld approximation, we project that the diffusivity of water molecules proximal to canonical B conformation is least for the minor groove of the canonical B-conformation. We determine that structure, composition, and conformation specific groove dimension together influence the local hydration characteristics and, therefore, are expected to be important determinants of biological processes.

The protein hydration layer in high glucose concentration: Dynamical responses in folded and intrinsically disordered dimeric states

This exposition reveals the effect of glucose as a molecular crowder on the solvent environment in proximity of the protein surface in putative folded (Ubiquitin) and intrinsically disordered (dimeric Amyloid beta) states. Atomistic simulations reveal markedly higher structural perturbation in the disordered systems due to crowding effects, while the folded state retains overall structural fidelity. Key hydrophobic contacts in the disordered dimer are lost. However, glucose induced crowding results in elevated hydration on surfaces of both protein systems. Despite evident differences in their structural responses, the hydration layer of both the folded and disordered states display a distinct enhancement in lifetimes of mean residence and rotational relaxation under the hyperglycemic conditions. The results are crucial in the light of emergent co-solvent induced biological phenomena in crowded media.

The distinct binding modes of pesticides affect the phase transitions of lysozyme

Studying the aggregation and nucleation of proteins in the presence of organic molecules is helpful for disclosing the mechanisms of protein crystallization.

Characterizing Structural Stability of Amyloid Motif Fibrils Mediated by Water Molecules

In biological systems, structural confinements of amyloid fibrils can be mediated by the role of water molecules. However, the underlying effect of the dynamic behavior of water molecules on structural stabilities of amyloid fibrils is still unclear. By performing molecular dynamics simulations, we investigate the dynamic features and the effect of interior water molecules on conformations and mechanical characteristics of various amyloid fibrils. We find that a specific mechanism induced by the dynamic properties of interior water molecules can affect diffusion of water molecules inside amyloid fibrils, inducing their different structural stabilities. The conformation of amyloid fibrils induced by interior water molecules show the fibrils' different mechanical features. We elucidate the role of confined and movable interior water molecules in structural stabilities of various amyloid fibrils. Our results offer insights not only in further understanding of mechanical features of amyloids as mediated by water molecules, but also in the fine-tuning of the functional abilities of amyloid fibrils for applications.