UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology

Date

4-7-2017

Document Type

Article

Disciplines

Biochemistry | Enzymes and Coenzymes | Molecular Biology | Structural Biology

Abstract

Many viruses use a powerful terminase motor to pump their genome inside an empty procapsid shell during virus maturation. The large terminase (TerL) protein contains both enzymatic activities necessary for packaging in such viruses: the adenosine triphosphatase (ATPase) that powers DNA translocation and an endonuclease that cleaves the concatemeric genome at both initiation and completion of genome packaging. However, how TerL binds DNA during translocation and cleavage remains mysterious. Here we investigate DNA binding and cleavage using TerL from the thermophilic phage P74-26. We report the structure of the P74-26 TerL nuclease domain, which allows us to model DNA binding in the nuclease active site. We screened a large panel of TerL variants for defects in binding and DNA cleavage, revealing that the ATPase domain is the primary site for DNA binding, and is required for nuclease activity. The nuclease domain is dispensable for DNA binding but residues lining the active site guide DNA for cleavage. Kinetic analysis of DNA cleavage suggests flexible tethering of the nuclease domains during DNA cleavage. We propose that interactions with the procapsid during DNA translocation conformationally restrict the nuclease domain, inhibiting cleavage; TerL release from the capsid upon completion of packaging unlocks the nuclease domains to cleave DNA.

Rights and Permissions

© The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

DOI of Published Version

10.1093/nar/gkw1356

Source

Nucleic Acids Res. 2017 Apr 7;45(6):3591-3605. doi: 10.1093/nar/gkw1356. Link to article on publisher's site

Related Resources

Link to Article in PubMed

Keywords

adenosine triphosphatases dna, kinetics, cytokinesis, nuclease, dna cleavage, binding (molecular function)

Journal Title

Nucleic acids research

PubMed ID

28082398

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

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