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Possible basis for specificity in attachment of histones to DNA in relation to genetic control in mRNA synthesis

Authors
Journal
Journal of Theoretical Biology
0022-5193
Publisher
Elsevier
Publication Date
Volume
29
Issue
1
Identifiers
DOI: 10.1016/0022-5193(70)90114-1
Disciplines
  • Chemistry

Abstract

Abstract New stereochemically and energetically permissible patterns are advanced which encompass sufficient complementary attachment specificity potentials in histones and in DNA trinucleotides, as a result of which genetic control by histones could be effectively exercised. While the strongest histone attachments to DNA are the non-specific ionic linkages, specificity of attachment can be ensured by weaker—but nevertheless complementary—H ... bonding and hydrophobic associations. The respective specificity potentials have been computed to be covered by the following: Trinucleotide specificity. Each of the 64 permissible trinucleotides can be differentiated—in the wide groove of the double helix of the B-form of DNA—from all other trinucleotides in terms of numbers and location of H ... acceptor groups and hydrophobic methyl groups. Histone specificity. Sufficient histone specificity can be attained in two ways: (a) a particular histone group may contain numerous polypeptides all of which have the same physicochemical characteristics of amino acid analysis, chromatography and electrophoresis, despite having different amino acid sequences; and (b) a particular histone with a defined amino acid sequence may possess a number of segments each of which is capable of existing in a number of alternative configurations. A particular configuration may be stabilized only when attached to a complementary site on specific tri- or oligonucleotides. Single-stranded mRNA biosynthesis. The relevant part of the wide groove of the double helix of DNA is considered to be covered by pairs of parallel aligned histones in each of which the two partners are held with unequal strength by the H ... and hydrophobic linkages. Selective unmasking takes place by rupture of the weaker linkages, which process enables the particular histone partner to turn, on its ionic linkage, away from the wide groove. This allows the corresponding DNA strand to be transcribed, while the complementary strand remains masked by the more strongly held histone partner. The patterns proposed enable prediction of selection of the mRNA sequence to be transcribed.

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