Download MendeleyDuplexes Formed by G 4 C 2 Repeats Contain Alternate Slow- and Fast-Flipping G·G Base Pairs.
Maity, A., Winnerdy, F.R., Chen, G., Phan, A.T.(2021) Biochemistry 60: 1097-1107
- PubMed: 33750098
- DOI: https://doi.org/10.1021/acs.biochem.0c00916
- Primary Citation of Related Structures:
7CUK - PubMed Abstract:
Aberrant expansion of the hexanucleotide GGGGCC (or G 4 C 2 ) repeat in the human C9ORF72 gene is the most common genetic factor found behind amyotrophic lateral sclerosis and frontotemporal dementia. The hypothesized pathways, through which the repeat expansions contribute to the pathology, involve one or more secondary structural forms of the DNA and/or RNA sequences, such as G-quadruplexes, duplexes, and hairpins. Here, we study the structures of DNA and RNA duplexes formed by G 4 C 2 repeats, which contain G( syn )·G( anti ) base pairs flanked by either G·C or C·G base pairs. We show that duplexes formed by G 4 C 2 repeats contain alternately two types of G·G pair contexts exhibiting different syn-anti base flipping dynamics (∼100 ms vs ∼2 ms for DNA and ∼50 ms vs ∼20 ms for RNA at 10 °C, respectively) depending on the flanking bases, with the slow-flipping G·G pairs being flanked by a guanine at the 5'-end and the fast-flipping G·G pairs being flanked by a cytosine at the 5'-end. Our findings on the structures and dynamics of G·G base pairs in DNA and RNA duplexes formed by G 4 C 2 repeats provide a foundation for further studies of the functions and targeting of such biologically relevant motifs.
Organizational Affiliation:
School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
