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Journal of Nucleic Acids
Volume 2017 (2017), Article ID 9170371, 14 pages
Research Article

Telomeric G-Quadruplexes: From Human to Tetrahymena Repeats

1Department of Biochemistry, Institute of Chemistry, Faculty of Sciences, P. J. Šafárik University, 04001 Kosice, Slovakia
2Department of Biological Sciences/RNA Institute, University at Albany, SUNY, Albany, NY 12222, USA
3Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovakia

Correspondence should be addressed to Viktor Víglaský

Received 30 July 2017; Revised 11 November 2017; Accepted 5 December 2017; Published 28 December 2017

Academic Editor: Shozeb Haider

Copyright © 2017 Erika Demkovičová et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The human telomeric and protozoal telomeric sequences differ only in one purine base in their repeats; TTAGGG in telomeric sequences; and TTGGGG in protozoal sequences. In this study, the relationship between G-quadruplexes formed from these repeats and their derivatives is analyzed and compared. The human telomeric DNA sequence G3(T2AG3)3 and related sequences in which each adenine base has been systematically replaced by a guanine were investigated; the result is Tetrahymena repeats. The substitution does not affect the formation of G-quadruplexes but may cause differences in topology. The results also show that the stability of the substituted derivatives increased in sequences with greater number of substitutions. In addition, most of the sequences containing imperfections in repeats which were analyzed in this study also occur in human and Tetrahymena genomes. Generally, the presence of G-quadruplex structures in any organism is a source of limitations during the life cycle. Therefore, a fuller understanding of the influence of base substitution on the structural variability of G-quadruplexes would be of considerable scientific value.