Non-bulk-like solvent behavior in the ribosome exit tunnel

Area of Science:

• Molecular Biology
• Biophysics
• Computational Chemistry

Background:

• Nascent proteins exit the ribosome via a tunnel, crucial for translation.
• The behavior of water within this confined biological space remains poorly understood.
• Traditional models describe confined water as continuous or discrete, lacking nuance.

Purpose of the Study:

• To investigate the thermodynamic and kinetic properties of water within the ribosome exit tunnel.
• To challenge the simplistic two-state model of confined solvent behavior.
• To understand how tunnel-confined water influences molecular processes.

Main Methods:

• Atomistic molecular dynamics simulations were employed.
• Analysis focused on water's rotational dynamics and dielectric properties.
• Solvation landscape and diffusion rates were characterized.

Main Results:

• Water in the ribosome exit tunnel displays non-bulk-like thermodynamic and kinetic properties.
• The tunnel creates a complex microenvironment with perturbed rotational dynamics.
• Heterogeneous dielectric behavior, a rugged solvation landscape, and retarded diffusion were observed.

Conclusions:

• Confined water's properties significantly deviate from bulk water and simple models.
• This unique solvent environment likely impacts co-translational folding and antibiotic binding.
• The findings have implications for understanding other biological cavities.