BioProject

Lcn972 is a non-modified bacteriocin that targets exclusively Lactococcus sp. Addition of Lcn972 inhibits cell wall biosynthesis at the septum by binding to the cell wall precursor lipid II. Resistance to Lcn972 develops upon selection with subinhibitory concentrations. The transcriptome of the highly resistant L. lactis D1 derived from the susceptible strain L. lactis MG1614 was compared. Fourteen genes were significantly up-regulated and 29 were down-regulated (expression change > 2-fold, p<0.001). Down-regulation was mostly found in sugar catabolic genes. Up-regulated genes included members of the cell envelope stress (CesR) regulon, the penicillin-binding protein pbpX and llmg2447, which may encode a putative extracytoplasmic function (ECF) anti-sigma factor located downstream of a non-functional ECF-sigX. Up-regulation of llmg2447 was linked to integration of IS981 that exchanged the -35 promoter region of llmg2447. Over-expression of llmg2447 resulted in highly Lcn972-resistant L. lactis transformants. Overall design: The transcriptomes of Lactococcus lactis MG1614 susceptible to Lcn972 and L. lactis D1 resistant to Lcn972, grown under laboratory conditions, were compared using four biological replicates.