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Publication Abstract from PubMed

Aberrant expansion of the hexanucleotide GGGGCC (or G4C2) 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 G4C2 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 G4C2 repeats contain alternately two types of G.G pair contexts exhibiting different syn-anti base flipping dynamics ( approximately 100 ms vs approximately 2 ms for DNA and approximately 50 ms vs approximately 20 ms for RNA at 10 degrees 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 G4C2 repeats provide a foundation for further studies of the functions and targeting of such biologically relevant motifs.

Duplexes Formed by G4C2 Repeats Contain Alternate Slow- and Fast-Flipping G.G Base Pairs.,Maity A, Winnerdy FR, Chen G, Phan AT Biochemistry. 2021 Mar 22. doi: 10.1021/acs.biochem.0c00916. PMID:33750098^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.