Transcriptional regulation of fatty acid biosynthesis in Lactococcus lactis

Here we study the influence of the putative fatty acid biosynthesis (FAB) regulator FabT (originally called RmaG [Llmg_1788]) on gene transcription in Lactococcus lactis MG1363. A strain with a knockout mutation of the putative regulator was constructed, and its transcriptome was compared to that of the wild-type strain. Almost all FAB genes were significantly upregulated in the knockout. Using electrophoretic mobility shift assays (EMSAs) and DNase I footprinting, the binding motif of the regulator and the binding locations in the genome were characterized. Fatty acid composition analysis revealed that a strain lacking FabT contained significantly more saturated acyl chains in its phospholipids. This observation demonstrates that the vital pathway of FAB in L. lactis is regulated by the repressor FabT.