DNA methylation epigenetically regulates gene expression in Burkholderia cenocepacia

Respiratory tract infections by the opportunistic pathogen often lead to severe lung damage in cystic fibrosis (CF) patients. New insights in how to tackle these infections might emerge from the field of epigenetics, as DNA methylation has shown to be an important regulator of gene expression. The present study focused on two DNA methyltransferases (MTases) in strains J2315 and K56-2, and their role in regulating gene expression. predicted DNA MTase genes BCAL3494 and BCAM0992 were deleted in both strains, and the phenotypes of the resulting deletion mutants were studied: deletion mutant ΔBCAL3494 showed changes in biofilm structure and cell aggregation, ΔBCAM0992 was less motile. wild type cultures treated with sinefungin, a known DNA MTase inhibitor, exhibited the same phenotype as DNA MTase deletion mutants. Single-Molecule Real-Time sequencing was used to characterize the methylome of , including methylation at the origin of replication, and motifs CACAG and GTWWAC were identified as targets of BCAL3494 and BCAM0992, respectively. All genes with methylated motifs in their putative promoter region were identified and qPCR experiments showed an upregulation of several genes, including biofilm and motility related genes, in MTase deletion mutants with unmethylated motifs, explaining the observed phenotypes in these mutants. In summary, our data confirm that DNA methylation plays an important role in regulating the expression of genes involved in biofilm formation and motility.