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Published on: July 26, 2024
Strong subunit coordination drives a powerful viral DNA packaging motor
Benjamin T Andrews1, Carlos Enrique Catalano
1Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA.
Summary
Terminase enzymes, powerful viral motors, require strong protomer coordination for DNA packaging. A specific mutant reveals how ATP hydrolysis and DNA movement are linked, impacting both maturation and packaging functions.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Terminase enzymes are viral motors essential for DNA packaging into capsids.
- These motors are among the most powerful known molecular machines.
- They perform genome maturation and packaging functions.
Purpose of the Study:
- To investigate the mechanism of terminase enzymes, specifically the motor from bacteriophage lambda.
- To understand the relationship between ATP hydrolysis and DNA translocation.
- To elucidate the coordination requirements for genome maturation and packaging.
Main Methods:
- Site-directed mutagenesis to create a packaging-deficient mutant (K76R).
- Biochemical assays to analyze enzyme activity and ATP hydrolysis.
- Assembly of chimeric motors using wild-type and mutant protomers.
- Characterization of genome maturation and packaging complexes.
Main Results:
- A specific mutant (K76R) was identified as deficient in DNA packaging.
- Strong protomer coordination is essential for DNA packaging; even one mutant protomer inhibits activity.
- Genome maturation involves a "dimer-of-dimers" complex with half-site reactivity.
- A model for the motor's alternation between maturation and packaging states was proposed.
Conclusions:
- Terminase motor function relies on highly coordinated protomer activity.
- The findings provide insights into the fundamental principles of viral DNA packaging motors.
- This research is relevant to all prokaryotic and eukaryotic terminase enzymes.
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