The major G-quadruplex formed in the human BCL-2 proximal promoter adopts a parallel structure with a 13-nt loop in k+ solution

Prashansa Agrawal, Clement Lin, Raveendra I. Mathad, Megan Carver, Danzhou Yang

Research output: Contribution to journalArticlepeer-review

97 Scopus citations


The human BCL-2 gene contains a 39-bp GC-rich region upstream of the P1 promoter that has been shown to be critically involved in the regulation of BCL-2 gene expression. Inhibition of BCL-2 expression can decrease cellular proliferation and enhance the efficacy of chemotherapy. Here we report the major G-quadruplex formed in the Pu39 G-rich strand in this BCL-2 promoter region. The 1245G4 quadruplex adopts a parallel structure with one 13-nt and two 1-nt chain-reversal loops. The 1245G4 quadruplex involves four nonsuccessive G-runs, I, II, IV, V, unlike the previously reported bcl2 MidG4 quadruplex formed on the central four G-runs. The parallel 1245G4 quadruplex with the 13-nt loop, unexpectedly, appears to be more stable than the mixed parallel/antiparallel MidG4. Parallel-stranded structures with two 1-nt loops and one variable-length middle loop are found to be prevalent in the promoter G-quadruplexes; the variable middle loop is suggested to determine the specific overall structure and potential ligand recognition site. A limit of 7 nt in loop length is used in all quadruplex-predicting software. Thus, the formation and high stability of the 1245G4 quadruplex with a 13-nt loop is significant. The presence of two distinct interchangeable G-quadruplexes in the overlapping region of the BCL-2 promoter is intriguing, suggesting a novel mechanism for gene transcriptional regulation and ligand modulation.

Original languageEnglish (US)
Pages (from-to)1750-1753
Number of pages4
JournalJournal of the American Chemical Society
Issue number5
StatePublished - Feb 5 2014
Externally publishedYes

ASJC Scopus subject areas

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


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