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Probing the Potential Role of Non-B DNA Structures at Yeast Meiosis-Specific DNA Double-Strand Breaks

Kshirsagar, Rucha and Khan, Krishnendu and Joshi, Mamata V and Hosur, Ramakrishna V and Muniyappa, K (2017) Probing the Potential Role of Non-B DNA Structures at Yeast Meiosis-Specific DNA Double-Strand Breaks. In: BIOPHYSICAL JOURNAL, 112 (10). pp. 2056-2074.

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Official URL: https://doi.org/10.1016/j.bpj.2017.04.028


A plethora of evidence suggests that different types of DNA quadruplexes are widely present in the genome of all organisms. The existence of a growing number of proteins that selectively bind and/or process these structures underscores their biological relevance. Moreover, G-quadruplex DNA has been implicated in the alignment of four sister chromatids by forming parallel guanine quadruplexes during meiosis; however, the underlying mechanism is not well defined. Here we show that a G/C-rich motif associated with a meiosis-specific DNA double-strand break (DSB) in Saccharomyces cerevisiae folds into G-quadruplex, and the C-rich sequence complementary to the G-rich sequence forms an i-motif. The presence of G-quadruplex or i-motif structures upstream of the green fluorescent protein-coding sequence markedly reduces the levels of gfp mRNA expression in S. cerevisiae cells, with a concomitant decrease in green fluorescent protein abundance, and blocks primer extension by DNA polymerase, thereby demonstrating the functional significance of these structures. Surprisingly, although S. cerevisiae Hop1, a component of synaptonemal complex axial/lateral elements, exhibits strong affinity to G-quadruplex DNA, it displays a much weaker affinity for the i-motif structure. However, the Hop1 C-terminal but not the N-terminal domain possesses strong i-motif binding activity, implying that the C-terminal domain has a distinct substrate specificity. Additionally, we found that Hop1 promotes intermolecular pairing between G/C-rich DNA segments associated with a meiosis-specific DSB site. Our results support the idea that the G/C-rich motifs associated with meiosis-specific DSBs fold into intramolecular G-quadruplex and i-motif structures, both in vitro and in vivo, thus revealing an important link between non-B form DNA structures and Hop1 in meiotic chromosome synapsis and recombination.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the CELL PRESS, 50 HAMPSHIRE ST, FLOOR 5, CAMBRIDGE, MA 02139 USA
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 16 Jun 2017 10:27
Last Modified: 16 Jun 2017 10:27
URI: http://eprints.iisc.ac.in/id/eprint/57233

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