A short DNA sequence confers strong bleomycin binding to hairpin DNAs

Chenhong Tang, Ananya Paul, Mohammad P. Alam, Basab Roy, W. David Wilson, Sidney Hecht

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Bleomycins A5and B2were used to study the structural features in hairpin DNAs conducive to strong BLM-DNA interaction. Two members of a 10-hairpin DNA library previously found to bind most tightly to these BLMs were subsequently noted to share the sequence 5′-ACGC (complementary strand sequence 5′-GCGT). Each underwent double-strand cleavage at five sites within, or near, an eight base pair region of the DNA duplex which had been randomized to create the original library. A new hairpin DNA library was selected based on affinity for immobilized Fe(III)·BLM A5. Two of the 30 newly identified DNAs also contained the sequence 5′-ACGC/5′-GCGT. These DNAs bound to the Fe(II)·BLMs more tightly than any DNA characterized previously. Surface plasmon resonance confirmed tight Fe(III)·BLM B2binding and gave an excellent fit for a 1:1 binding model, implying the absence of significant secondary binding sites. Fe(II)·BLM A5was used to assess sites of double-strand DNA cleavage. Both hairpin DNAs underwent double-strand cleavage at five sites within or near the original randomized eight base region. For DNA 12, four of the five double-strand cleavages involved independent single-strand cleavage reactions; DNA 13 underwent double-strand DNA cleavage by independent single-strand cleavages at all five sites. DNA 14, which bound Fe·BLM poorly, was converted to a strong binder (DNA 15) by insertion of the sequence 5′-ACGC/5′-GCGT. These findings reinforce the idea that tighter DNA binding by Fe·BLM leads to increased double-strand cleavage by a novel mechanism and identify a specific DNA motif conducive to strong BLM binding and cleavage.

Original languageEnglish (US)
Pages (from-to)13715-13726
Number of pages12
JournalJournal of the American Chemical Society
Volume136
Issue number39
DOIs
StatePublished - Sep 4 2014

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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