Molecular Basis for Environment Sensing by a Nucleoid-Structuring Bacterial Protein Filament

Area of Science:

• Bacterial genetics and epigenetics
• Structural biology
• Computational biophysics

Background:

• The histone-like nucleoid structuring (H-NS) protein regulates gene expression in Gram-positive bacteria by condensing DNA.
• H-NS protein forms superhelical filaments sensitive to environmental factors like temperature and salinity, acting as a cellular sensor.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying H-NS filament's environmental sensitivity using multiscale modeling.
• To investigate how environmental changes induce heterogeneity within H-NS monomers and affect filament stability.

Main Methods:

• Multiscale modeling and simulations of superhelical H-NS filaments.
• Analysis of H-NS monomer heterogeneity and self-association dynamics.
• Probing H-NS-DNA complex architectures and their stability.

Main Results:

• Environmental conditions induce heterogeneity in H-NS monomers within the superhelical filament.
• Transient self-association within H-NS filaments generates temperature-inducible strain, potentially impacting DNA binding.
• Complexation with DNA enhances the stability of both H-NS superhelices and the DNA itself.

Conclusions:

• Provides detailed molecular insights into the environmental sensing capabilities of H-NS protein filaments.
• Demonstrates the role of H-NS filament dynamics and DNA interactions in bacterial gene regulation.
• Highlights the importance of multiscale modeling in understanding complex biological systems.