The mechano-chemistry of a monomeric reverse transcriptase

Area of Science:

• Molecular Biology
• Biophysics
• Enzymology

Background:

• Retroviral reverse transcriptase (RT) is crucial for synthesizing viral DNA from RNA.
• Understanding RT's polymerization mechanism under force is key to retroviral replication.
• Previous studies lacked detailed insights into RT's mechanical behavior and processivity.

Purpose of the Study:

• To investigate the mechanical properties of Murine Leukemia Virus reverse transcriptase during DNA synthesis.
• To elucidate the role of dNTP binding and template structure in RT's polymerization mechanism.
• To characterize the enzyme's dynamic states, including backtracking.

Main Methods:

• Utilized optical tweezers to apply mechanical force to the enzyme-template complex.
• Monitored strand-displacement polymerization by Murine Leukemia Virus reverse transcriptase in real-time.
• Analyzed enzyme behavior on structured DNA templates under varying conditions.

Main Results:

• Reverse transcriptase functions as a Brownian ratchet, with dNTP binding serving as the rectifying reaction.
• The enzyme exhibits passive polymerization, exploiting template thermal breathing for processivity.
• Evidence suggests RT enters a backtracking state from the pre-translocation complex.

Conclusions:

• Reverse transcriptase operates as a force-generating enzyme regulated by dNTP incorporation.
• The enzyme's ability to polymerize on structured templates highlights its adaptability.
• Characterization of the backtracking state provides new insights into RT's kinetic pathway.