Lu S. Zn2+ blocks annealing of complementary single-stranded DNA in a sequence-selective manner.
Sci Rep 2014;
4:5464. [PMID:
24965053 PMCID:
PMC4071324 DOI:
10.1038/srep05464]
[Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/11/2014] [Indexed: 12/19/2022] Open
Abstract
Zinc is the second most abundant trace element essential for all living organisms. In human body, 30–40% of the total zinc ion (Zn2+) is localized in the nucleus. Intranuclear free Zn2+ sparks caused by reactive oxygen species have been observed in eukaryotic cells, but question if these free Zn2+ outrages could have affected annealing of complementary single-stranded (ss) DNA, a crucial step in DNA synthesis, repair and recombination, has never been raised. Here the author reports that Zn2+ blocks annealing of complementary ssDNA in a sequence-selective manner under near-physiological conditions as demonstrated in vitro using a low-temperature EDTA-free agarose gel electrophoresis (LTEAGE) procedure. Specifically, it is shown that Zn2+ does not block annealing of repetitive DNA sequences lacking CG/GC sites that are the major components of junk DNA. It is also demonstrated that Zn2+ blocks end-joining of double-stranded (ds) DNA fragments with 3′ overhangs mimicking double-strand breaks, and prevents renaturation of long stretches (>1 kb) of denatured dsDNA, in which Zn2+-tolerant intronic DNA provides annealing protection on otherwise Zn2+-sensitive coding DNA. These findings raise a challenging hypothesis that Zn2+-ssDNA interaction might be among natural forces driving eukaryotic genomes to maintain the Zn2+-tolerant repetitive DNA for adapting to the Zn2+-rich nucleus.
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