Protein Dynamics Is Altered by a High Surface Density of Atomic Transfer Radical Polymerization Polymers

Area of Science:

• Biochemistry
• Polymer Chemistry
• Structural Biology

Background:

• RNA binding proteins are crucial for gene regulation.
• Understanding how external molecules affect protein structure is vital.
• Atomic Transfer Radical Polymerization (ATRP) offers controlled polymer synthesis.

Purpose of the Study:

• To investigate the impact of ATRP polymers on the structure and dynamics of the 14.5 kDa RNA binding protein, Rho130.
• To correlate protein modification sites with structural and dynamic changes.
• To elucidate the effects of initiator and polymer attachment on protein conformation.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy was employed to study protein structure and dynamics.
• Molecular Dynamics (MD) simulations were used to analyze protein solvent accessibility and conformational changes.
• Relaxation dispersion NMR was utilized to probe microsecond-millisecond timescale dynamics.

Main Results:

• Optimization of initiator coupling yielded a near-homogeneous sample of modified Rho130.
• ATR P initiator attachment induced localized structural changes in the N-terminal helical domain.
• Polymer growth, but not initiator attachment alone, reduced the dynamics of the protein's hydrophobic core.

Conclusions:

• ATRP polymers can significantly influence protein structure and dynamics.
• The ATRP initiator itself causes structural perturbations.
• Polymer conjugation modulates protein dynamics, particularly in the hydrophobic core.