Diversity in the lysis-integration region of oenophage genomes and evidence for multiple tRNA loci, as targets for prophage integration in Oenococcus oeni.

The central genomic regions of Oenococcus oeni phages fOg30 and fOgPSU1 have been compared with the equivalent regions of oenophages fOg44 and phi 10MC. In all cases, an almost identical endolysin gene was followed by one of two orfs, encoding putative holins (orf117 and orf163). The fOg44 endolysin was established as a secretory protein when expressed in Lactococcus lactis. Orf117 (from fOg44) promoted lysis of Escherichia coli cultures upon induction of a defective lambda Sam7 prophage, but Orf163 (from fOg30) failed to elicit a lysis response in this system. fOg44 and fOgPSU1 were shown to integrate at the 3' end of a tRNA(Glu) and a tRNA(Lys), respectively. Searching the available sequence of the O. oeni MCW genome for attP-like elements, two other tRNA targets could be proposed for prophage establishment. Between the lysis and integration elements, a diverse cluster of genes (absent in phi 10MC) was observed. One common gene in this "lysogenic conversion cluster" was experimentally confirmed as a transcriptional repressor, affecting the expression of a putative permease gene.