Exploring the Role of Lysine Acetylation During Biofilm Formation in Bacillus subtilis

Biofilms are structured communities of bacterial cells encased in a self-produced extracellular matrix, composed of polysaccharides, extracellular DNA, and proteins. Bacteria in a biofilm pose significant challenges in healthcare due to their resistance to disinfectants and tolerance to antibiotics. In some species, histone-like proteins were found to be important structural components of the biofilm. Nε-Lysine acetylation is a widespread post-translational modification (PTM) in bacteria, which can alter a protein’s function. The histone-like protein HBsu in Bacillus subtilis is acetylated at seven sites in vivo. We hypothesized that the acetylation state of HBsu may alter biofilm structure or the genetic programming, which are not mutually exclusive possibilities. To test this, we are constructing acetyl mimic (glutamine substitutions) and deacetyl mimic (arginine substitutions) mutations at the native locus in the biofilm-producing background, NCIB 3610. We have constructed 6 of 14 mutants thus far. Once a mutant is constructed, we monitor biofilm formation in LBGM media for colony morphology and pellicle structure. Our results show that wildtype forms highly wrinkled pellicles and colonies. Mutants at sites K37Q and K3R displayed smoother pellicles and brown-red pigmentation. In contrast, the mutants at sites K18Q, K18R, K37R, and K75Q displayed increased wrinkling, but showed no brown-red pigmentation. Additional assays were performed to quantify the biofilm mass and metabolic activity of each mutant as well. Once all 7 sites are analyzed, our findings will demonstrate how HBsu acetylation affects biofilm structure, potentially leading to the development of new drugs for combating biofilm-associated infections.