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A minimal kinetic model for a viral DNA packaging machine.
Qin Yang1, Carlos Enrique Catalano
1Department of Pharmaceutical Sciences and Molecular Biology Program, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
Biochemistry
|January 14, 2004
Summary
This study reveals a new kinetic model for bacteriophage lambda terminase, detailing how its ATPase and nuclease activities cooperate to package viral DNA. The model explains allosteric interactions, offering insights into virus assembly mechanisms.
Area of Science:
- Biochemistry
- Virology
- Molecular Biology
Background:
- Terminase enzymes are crucial for packaging viral DNA into procapsids in both prokaryotic and eukaryotic viruses.
- Bacteriophage lambda terminase exhibits multiple activities including nuclease, helicase, DNA translocase, and ATPase functions, with reported allosteric interactions between its catalytic sites.
Purpose of the Study:
- To investigate the allosteric interactions between the multiple catalytic sites of bacteriophage lambda terminase.
- To develop a kinetic model that explains the mechanism of viral DNA packaging by terminase enzymes.
Main Methods:
- Enzyme kinetics studies
- Photoaffinity labeling experiments
- Vanadate inhibition assays
Main Results:
- A minimal kinetic model for lambda terminase was established, incorporating an ADP-driven conformational change.
- This model explains the allosteric interactions between catalytic sites and the activation of the packaging machine.
- The findings reconcile existing kinetic data for lambda terminase.
Conclusions:
- The proposed model provides a unifying mechanism for terminase enzyme function during viral DNA packaging.
- This mechanism, involving ADP-driven conformational reorganization, may be conserved across diverse viruses, including herpesviruses.
- The study enhances the global understanding of the enzymology of virus assembly.