2020  1,374
2019  1,023
2018  0,932
2017  0,977
2016  0,799
2015  0,662
2014  0,740
2013  0,739
2012  0,637
2011  0,658
2010  0,654
2009  0,570
2008  0,849
2007  0,805
2006  0,330
2005  0,435
2004  0,623
2003  0,567
2002  0,641
2001  0,490
2000  0,477
1999  0,762
1998  0,785
1997  0,507
1996  0,518
1995  0,502
Vol 44(2010) N 3 p. 458-465;
V.K. Gasanova1*, N.V. Ryadninskaya1, K. Gaillard2, F. Strauss2, G.A. Belitsky1, M.G. Yakubovskaya1

Invasion of Complementary Oligonucleotides into (CA/TG) 31 Repetitive Region of Linear and Circular DNA Duplexes

1Laboratory of carcinogen screening methods, Institute of Carcinogenesis, Cancer Research Center Russian Academy of Medical Sciences, Moscow, 115478 Russia
2Universite Pierre et Marie Curie, Centre National de la Recherche Scientifique, Paris, 75006, France

Received - 2009-07-23; Accepted - 2009-10-12

(CA/TG) n repeats belong to microsatellite DNA. They are the most abundant among the other dinucleotide repeats in mammals, constituting approximately 0.25% of the entire genome. These repeats are recombination hot spots; however, the corresponding mechanisms are yet vague. We postulated that one of the reasons underlying an increase in the recombination frequency in the repetitive region could be the conformational characteristics of duplex resulting from a specific geometry of base-stacking contacts, providing for initiation of a single-stranded DNA invasion in the duplex homologous regions. This work for the first time demonstrates a DNA-DNA interaction of the d(CA) 10 and d(TG) 10 oligonucleotides with linear and circular duplexes containing (CA/TG) 31 repeats during their coincubation in a protein-free water solution at 37C. Using radioactively labeled oligonucleotides, we demonstrated that the duplex-oligonucleotide interaction intensity depended on the molar ratio of duplex-to-oligonucleotide at a duplex concentration of 30nM. A decrease in this concentration to 3 nM had no effect on the intensity of oligonucleotide invasion. It was demonstrated that over 1% of the duplexes yet much less than 10% were involved in the interaction with oligonucleotides assuming that one oligonucleotide molecule interacted with one molecule of the duplex. Analysis of the kinetics showed that d(CA) 10 invasion commenced from the first minute of incubation with duplexes, while d(TG) 10 interacted with the duplex even at a higher rate. The role of conformational plasticity of CA/TG repeats in the discovered interaction is discussed as well as its biological significance, in particular, the role of CA microsatellites in the initiation of homologous recombination.

DNA, noncanonical structure, (CA/TG) repeats, duplexes, oligonucleotide invasion, CA microsatellites