Host genetic requirements for DNA release of lactococcal phage TP901‐1

Abstract

The first step in phage infection is the recognition of, and adsorption to, a receptor located on the host cell surface. This reversible host adsorption step is commonly followed by an irreversible event, which involves phage DNA delivery or release into the bacterial cytoplasm. The molecular components that trigger this latter event are unknown for most phages of Gram‐positive bacteria. In the current study, we present a comparative genome analysis of three mutants of Lactococcus cremoris 3107, which are resistant to the P335 group phage TP901‐1 due to mutations that affect TP901‐1 DNA release. Through genetic complementation and phage infection assays, a predicted lactococcal three‐component glycosylation system (TGS) was shown to be required for TP901‐1 infection. Major cell wall saccharidic components were analysed, but no differences were found. However, heterologous gene expression experiments indicate that this TGS is involved in the glucosylation of a cell envelope‐associated component that triggers TP901‐1 DNA release. To date, a saccharide modification has not been implicated in the DNA delivery process of a Gram‐positive infecting phage.

Partial Atomic Model of the Tailed Lactococcal Phage TP901-1 as Predicted by AlphaFold2: Revelations and Limitations

“…Furthermore, despite sequence disparity between phages of the same or distinct bacterial host species, the structure of their components is often conserved [4,[12][13][14][15]. The temperate lactococcal P335 phage TP901-1 is particularly well characterized with respect to its three-dimensional structure and the interactions with its host [5,[16][17][18]. Furthermore, it has been employed as a model to understand the phenomenon of lysogeny and the factors that underpin the lytic-lysogenic lifestyle decision process [19][20][21].…”