Biophysical and structural characterization of a multifunctional viral genome packaging motor

Nikolai Prokhorov, Christal R. Davis, Kashyap Maruthi, Qin Yang, Michael B. Sherman, Michael Woodson, Mark A. White, Lohra M. Miller, Martin F. Jarrold, Carlos E. Catalano, Marc Morais

Research output: Contribution to journalArticlepeer-review

Abstract

The large dsDNA viruses replicate their DNA as concatemers consisting of multiple covalently linked genomes. Genome packaging is catalyzed by a terminase enzyme that excises individual genomes from concatemers and packages them into preassembled procapsids. These disparate tasks are catalyzed by terminase alternating between two distinct states—a stable nuclease that excises individual genomes and a dynamic motor that translocates DNA into the procapsid. It was proposed that bacteriophage λ terminase assembles as an anti-parallel dimer-of-dimers nuclease complex at the packaging initiation site. In contrast, all characterized packaging motors are composed of five terminase subunits bound to the procapsid in a parallel orientation. Here, we describe biophysical and structural characterization of the λ holoenzyme complex assembled in solution. Analytical ultracentrifugation, small angle X-ray scattering, and native mass spectrometry indicate that 5 subunits assemble a cone-shaped terminase complex. Classification of cryoEM images reveals starfish-like rings with skewed pentameric symmetry and one special subunit. We propose a model wherein nuclease domains of two subunits alternate between a dimeric head-to-head arrangement for genome maturation and a fully parallel arrangement during genome packaging. Given that genome packaging is strongly conserved in both prokaryotic and eukaryotic viruses, the results have broad biological implications.

Original languageEnglish (US)
Pages (from-to)831-843
Number of pages13
JournalNucleic acids research
Volume52
Issue number2
DOIs
StatePublished - Jan 25 2024
Externally publishedYes

ASJC Scopus subject areas

  • Genetics

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