Mechanistic Insights into Dioxygen Transport Routes in the PHD2 Oxygenase from Long-Time Scale Simulations

Area of Science:

• Biochemistry
• Biophysics
• Computational Biology

Background:

• Metalloenzymes are crucial biological catalysts.
• Understanding dioxygen access to active sites is key for enzyme kinetics and catalyst design.
• PHD2 oxygenase regulates hypoxia signaling by hydroxylating HIF-1α.

Purpose of the Study:

• To investigate dioxygen transport mechanisms in the PHD2 oxygenase using extended molecular dynamics simulations.
• To identify and characterize dynamic pathways and internal cavities involved in substrate access.
• To provide insights for modulating enzyme activity and designing novel molecular catalysts.

Main Methods:

• Classical molecular dynamics simulations (over 20 μs).
• Analysis of dynamic dioxygen transport routes.
• Identification of transient channels and internal hydrophobic cavities.
• Analysis of cavity-lining residues.

Main Results:

• Multiple dynamic dioxygen transport routes identified from solvent to the active site.
• Dioxygen transport occurs on diverse timescales, including rapid exchange and long residence times in cavities.
• Internal hydrophobic cavities act as dynamic reservoirs, modulating dioxygen availability.
• Cavity-lining residues identified as potential targets for modulating catalytic rates.

Conclusions:

• Extended simulations reveal complex, time-dependent dioxygen access mechanisms in PHD2.
• Internal cavities play a significant role in modulating dioxygen availability and enzyme kinetics.
• The findings refine the mechanistic model of dioxygen access in PHD2 and offer principles for catalyst design.