Lack of the host membrane protease FtsH hinders release of the Lactococcus lactis bacteriophage TP712

The temperate bacteriophage TP712 was unable to plaque on Lactococcus lactis ΔftsH lacking the membrane protease FtsH and complementation in trans restored the WT phenotype. Absence of ftsH did not hinder phage adsorption, phage DNA delivery or activation of the lytic cycle. Thin sections revealed that TP712 virions appeared to be correctly assembled inside the ΔftsH host, but were not released. These virions were infective, demonstrating that a functional host FtsH is required by TP712 to proceed effectively with lysis of the host.