Genome-wide Screens Reveal Escherichia Coli Genes Required for Growth of T1-like Phage LL5 and rV5-like Phage LL12

Abstract

Factors affecting the host-virus interaction must be understood for the effective application of bacteriophages to combat bacterial pathogens. Two novel E. coli phages, the T1-like siphophage LL5 and the rV5-like myophage LL12, were subjected to forward genetic screens against the Keio collection, a library of single non-essential gene deletions in E.coli str. BW25113. These genome-wide screens and subsequent experiments identified eight genes required for efficient propagation of phage LL5 and six genes required for propagation of LL12. The majority of the genes identified were involved in production of the phage receptors. E. coli mutants deficient in heptose II and the phosphoryl substituent of heptose I of the inner core lipopolysaccharide (LPS) were unable to propagate phage LL5, as were mutants deficient in the outer membrane protein TolC. Mutants lacking glucose I of the LPS outer core failed to propagate LL12. Two cytoplasmic chaperones, PpiB and SecB, were found to be required for efficient propagation of phage LL5 but not LL12. This approach may be useful for identifying phage receptors and required host factors in other phages, which would provide valuable information for their potential use as therapeutics and for phage engineering.

Isolation and Characterization of Pectobacterium Phage vB_PatM_CB7: New Insights into the Genus Certrevirus

“…Comparisons of these two phages with CB7 show that they share twenty structural proteins, with minimal similarity occurring between several proteins predicted to play roles in tail fibre structure (Supplementary information 1, Table S9). It has been described that host cell binding receptors of Cretrevirus phages ΦTE and CR3 are the flagella of the host cell, while lipopolysaccharide (LPS) is believed to be the host cell binding receptor of other phages belonging to the subfamily Vequintavirinae [14,16,39] The lack of homology among these tail fibre proteins likely reflects differences among the host cell receptors recognized by phages belonging to different genera of Vequintavirinae.…”

High-throughput mapping of the phage resistance landscape inE. coli

“…There have been few attempts to use genetic approaches for studying genome-wide host factors essential in phage infection. These loss-of-function (LOF) genetic screens broadly use bacterial saturation mutagenesis [48,53,[57][58][59][60] or an arrayed library of single-gene deletion strains for studying phage-host interactions [49,50,52,61,62]. Consequently, these studies have generally involved laborious experiments on relatively few phages and their hosts, and scaling the approach to characterize hundreds of phages is challenging.…”