Interaction between DNA and chromosomal proteins HMGB1 and H1 studied by IR/VCD spectroscopy

Binary complexes of calf thymus DNA with calf thymus non-histone chromosomal protein HMGB1 and linker histone H1 were studied using FTIR/VCD spectroscopy. The spectroscopic data showed that the interaction of the protein HMGB1 and histone H1 with DNA resulted in formation of two different types of the macromolecular complexes. Histone H1 retained its native structure even at high concentrations and induced DNA condensation upon binding at the protein to DNA ratio r (w/w) in the complex r ⩾ 0.3. HMGB1 demonstrated the ability to form soluble complexes at considerably higher protein to DNA ratios. The obtained data suggest that the HMGB1 also participated in the protein–protein interactions via its C-terminal domain.