Interaction of Extracellular Histones with DNA and Actin Filaments

Histones are located in the cell nucleus. They are positively charged small proteins which became extracellular upon apoptosis, necrosis, and infection – induced cell death. The mixture of extracellular Histones was shown to bundle Actin filaments and digested by bacterial proteases, which was inhibited by DNA and Actin. Here we studied the interaction of five major family of Histones, H2A, H2B, H3.1, H1 and H4, with DNA and Actin filaments. We found that all the Histones studied bound to DNA, increased the viscosity of Actin containing solutions and bundled Actin filaments in various degrees. The bundling of Actin filaments by Histones was inhibited by DNA, NaCl and DNase1. DNA and Actin filaments also inhibited the proteolysis of the five Histones by Subtilisin, Fusolisin and Pseudomonas Aeruginosa bacterial proteases. Both the degree of the proteolysis and its inhibition was different with various Histones. The results indicate that all the Histones studied bind strongly to the negatively charged DNA and to the Actin filaments.