The cellular response of Lactococcus lactis MG1363 to infection by the virulent phage p2 was characterized through labelfree quantitative proteomics. Combined with a targeted approach, we identified the highest proteome coverage for phage p2, a model for the most predominant group of lactococcal phages in the dairy industry worldwide. Four bacterial gene candidates possibly involved in phage infection were disrupted through specific knockouts to investigate their importance. Deletion of gene llmg_0219 (unknown function) resulted in a resistance to phage p2.
Graphical Abstract
Highlights• The proteomes of L. lactis MG1363 and phage p2 at different stages of infection were characterized.• 16% (226/1412) of the bacterial proteins detected were unique to infected cultures.• A targeted approach using synthetic peptides improved the coverage of phage p2 proteome.• By means of proteogenomics, we uncovered a conserved phage protein coded by a previously unannotated gene.• Deletion of the bacterial gene llmg_0219 (unknown function) impedes phage p2 infection.