[Prediction in histones of the DNA-recognizing protein superstructure alpha helix-turn-alpha helix]

The localization of DNA-recognizing supersecondary structure alpha-helix--turn--alpha-helix in 85 amino acid sequences of histones is predicted. According to the prediction method based on the necessary requirements of amino acid coding this structure may be localized in the following segments of amino acid sequences of calf thymus histones: H1--90--112, H2A--54--76, H2B--50--72 and 102--124, H3--15--37 and 73--95, H4--5--27 or 6--28 and 32--54 or 42--64. According to the known experimental data on the secondary structure of histones only the following localizations are possible: H1--90--112, H2A--54--76, H2B--50--72, H3--73--95, H4--42--64. Using the known experimental data on DNA-histone interactions it is possible to suggest that these localizations of structures alpha-helix--turn--alpha-helix possible in histones H2A, H2B and H4 allows them to participate in close or structurally essential interactions of histones with DNA. The role of the predicted structure in nucleosome formation and in the autoregulation of histone biosynthesis is discussed.