Antimicrobial properties of arginine- and lysine-rich histones and involvement of bacterial outer membrane protease T in their differential mode of actions

► We first found the direct anti-E. coli activity of histone H3. ► The modes of antimicrobial action of Arg-rich (H3 and H4) and Lys-rich (H2B) histones are different. ► We found that the Arg-rich histones disrupt the cell membrane of ompT-expressing E. coli strains by forming blebs. ► The Lys-rich histone translocates the membrane without causing membrane lysis. ► Bacterial OmpT is involved in these modes of action through digestion of histones.