Download MendeleyTerminase Subunits from the Pseudomonas-Phage E217.
Lokareddy, R.K., Hou, C.D., Doll, S.G., Li, F., Gillilan, R.E., Forti, F., Horner, D.S., Briani, F., Cingolani, G.(2022) J Mol Biol 434: 167799-167799
- PubMed: 36007626
- DOI: https://doi.org/10.1016/j.jmb.2022.167799
- Primary Citation of Related Structures:
7UXE, 8DKR - PubMed Abstract:
Pseudomonas phages are increasingly important biomedicines for phage therapy, but little is known about how these viruses package DNA. This paper explores the terminase subunits from the Myoviridae E217, a Pseudomonas-phage used in an experimental cocktail to eradicate P. aeruginosa in vitro and in animal models. We identified the large (TerL) and small (TerS) terminase subunits in two genes ∼58 kbs away from each other in the E217 genome. TerL presents a classical two-domain architecture, consisting of an N-terminal ATPase and C-terminal nuclease domain arranged into a bean-shaped tertiary structure. A 2.05 Å crystal structure of the C-terminal domain revealed an RNase H-like fold with two magnesium ions in the nuclease active site. Mutations in TerL residues involved in magnesium coordination had a dominant-negative effect on phage growth. However, the two ions identified in the active site were too far from each other to promote two-metal-ion catalysis, suggesting a conformational change is required for nuclease activity. We also determined a 3.38 Å cryo-EM reconstruction of E217 TerS that revealed a ring-like decamer, departing from the most common nonameric quaternary structure observed thus far. E217 TerS contains both N-terminal helix-turn-helix motifs enriched in basic residues and a central channel lined with basic residues large enough to accommodate double-stranded DNA. Overexpression of TerS caused a more than a 4-fold reduction of E217 burst size, suggesting a catalytic amount of the protein is required for packaging. Together, these data expand the molecular repertoire of viral terminase subunits to Pseudomonas-phages used for phage therapy.
Organizational Affiliation:
Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA.
