Structural basis of DNA packaging by a ring-type ATPase from an archetypal viral system

Herman K H Fung, Shelley Grimes, Alexis Huet, Robert L Duda, Maria Chechik, Joseph Gault, Carol V Robinson, Roger W Hendrix, Paul J Jardine, James F Conway, Christoph G Baumann, Alfred A Antson

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Many essential cellular processes rely on substrate rotation or translocation by a multi-subunit, ring-type NTPase. A large number of double-stranded DNA viruses, including tailed bacteriophages and herpes viruses, use a homomeric ring ATPase to processively translocate viral genomic DNA into procapsids during assembly. Our current understanding of viral DNA packaging comes from three archetypal bacteriophage systems: cos, pac and phi29. Detailed mechanistic understanding exists for pac and phi29, but not for cos. Here, we reconstituted in vitro a cos packaging system based on bacteriophage HK97 and provided a detailed biochemical and structural description. We used a photobleaching-based, single-molecule assay to determine the stoichiometry of the DNA-translocating ATPase large terminase. Crystal structures of the large terminase and DNA-recruiting small terminase, a first for a biochemically defined cos system, reveal mechanistic similarities between cos and pac systems. At the same time, mutational and biochemical analyses indicate a new regulatory mechanism for ATPase multimerization and coordination in the HK97 system. This work therefore establishes a framework for studying the evolutionary relationships between ATP-dependent DNA translocation machineries in double-stranded DNA viruses.

Original languageEnglish
Article numbergkac647
Number of pages14
JournalNucleic Acids Research
Early online date10 Aug 2022
Publication statusE-pub ahead of print - 10 Aug 2022

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© The Author(s) 2022.

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