Complex between human RNase HI and the phosphonate-DNA/RNA duplex: molecular dynamics study.

Area of Science:

• Biochemistry
• Molecular Biology
• Computational Chemistry

Background:

• Oligonucleotides are key in molecular biology and therapeutics.
• RNase H enzymes play a crucial role in RNA processing and are therapeutic targets.
• Understanding enzyme-substrate interactions is vital for drug design.

Purpose of the Study:

• To investigate the binding of modified oligonucleotides to Human RNase H.
• To determine the impact of different phosphonate linkages on RNase H activity.
• To explore methods for stabilizing the binuclear active site of RNase H and related enzymes.

Main Methods:

• Molecular Dynamics (MD) simulations of varying lengths (200ns, 500ns, 1000ns).
• Utilizing one-atom and seven-point models for Mg(2+) to simulate the active site.
• Comparative analysis of Human RNase H and Thermus thermophilus Argonaute enzyme active sites.

Main Results:

• Oligonucleotides with 3'-O-P-CH2-O-5' phosphonate linkages successfully attach to Human RNase H.
• Alternating phosphonate and phosphodiester linkages elicit RNase H activity; 3'-O-CH2-P-O-5' linkages are inactive.
• A one-atom Mg(2+) model effectively stabilizes the binuclear active site, consistent with longer simulations and other enzymes like T. thermophilus Argonaute.

Conclusions:

• The specific 3'-O-P-CH2-O-5' phosphonate linkage is crucial for oligonucleotide binding and RNase H activity.
• The employed MD simulation approach, including the Mg(2+) model, is effective for studying enzyme active sites.
• The findings are transferable to other enzymes, such as Thermus thermophilus Argonaute, highlighting conserved catalytic mechanisms.