title: The enfolding arms of EcoRI endonuclease: role in DNA binding and cleavage.
abstract: The N-terminal segments of the EcoRI endonuclease dimer form part of mobile "arms" that encircle DNA in the recognition complex. By treating endonuclease-TCGCGAATTCGCG complexes with proteases, we have prepared a series of deletion derivatives lacking defined segments of the N-terminal region. The 5-12 segment is essential for DNA cleavage and forms one electrostatic interaction (per subunit) with DNA phosphate. These ionic contacts are directly across the double helix from the scissile phosphodiester bonds; they thus may permit the enfolding arms to immobilize DNA in apposition to the catalytic cleft and/or contribute to the unusual "kinked" conformation of DNA in the complex. Sequence specificity is fully retained when 28 residues are deleted from the N-terminus, but the complexes dissociate more rapidly.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D004262:DNA Restriction Enzymes / Q000378:metabolism*; D015246:Deoxyribonuclease EcoRI; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010447:Peptide Hydrolases; D011485:Protein Binding; D011487:Protein Conformation; D013379:Substrate Specificity
chemical_list: D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments; D004247:DNA; D004262:DNA Restriction Enzymes; D015246:Deoxyribonuclease EcoRI; D010447:Peptide Hydrolases