TY - JOUR
T1 - Overcoming potassium-mediated triplex inhibition
AU - Olivas, Wendy M.
AU - Maher, L. James
N1 - Funding Information:
We gratefully acknowledge Dr M. Matteucci for synthesis of ODN IX, and T. Chappell, D. Eicher, B. Gold and C. Mountjoy for their excellent technical assistance. This work was supported in part by grant 5 P30 CA36727-O8 from the National Cancer Institute, grant GM 47814 from the National Institutes of Health • and a Special Institutional Grant on Cancer Cause and Prevention from the American Cancer Society. W.M.O. is supported by a University of Nebraska Medical Center Bukey Fellowship. LJ.M. is arecipientof a Junior Faculty Research Award from the American Cancer Society.
PY - 1995/6/11
Y1 - 1995/6/11
N2 - Sequence-specific duplex DNA recognition by oligonucleotlde-dlrected triple helix formation Is a possible approach to In vivo gene inhibition. However, triple helix formation involving guanlne-rich oligo-nucleotides is Inhibited by physiological Ions, particularly K+, most likely due to oligonucleotide aggregation via guanine quartets. Three ollgodeoxynucleotlde (ODN) derivatives were tested for their ability to resist guanine quartet-mediated aggregation, yet form stable triplexes. Electrophoretic mobility shift and dimethyl sulfate footprinting assays were used to analyze the formation of triplexes Involving these oligonucleotide derivatives. In the absence of K+, all ODNs had similar binding affinities for the duplex target Triplexes involving a 14mer ODN derivative containing 7-deazaxanthine substituted for three thymine bases or an 18mer ODN containing two additional thymlnes on both the 5′ and 3′ termini were abolished by 50 mM K+. Remarkably, triplexes Involving an ODN derivative containing four 6-thloguanine bases substituted for guanine resisted K+ inhibition up to 200 mM. We hypothesize that the Increased radius and decreased electronegativity of sulfur in the 6-posltlon of guanine destabilize potential guanine quartets. These results improve the prospects for creating ODNs that might serve as specific and efficient gene repressors In vivo.
AB - Sequence-specific duplex DNA recognition by oligonucleotlde-dlrected triple helix formation Is a possible approach to In vivo gene inhibition. However, triple helix formation involving guanlne-rich oligo-nucleotides is Inhibited by physiological Ions, particularly K+, most likely due to oligonucleotide aggregation via guanine quartets. Three ollgodeoxynucleotlde (ODN) derivatives were tested for their ability to resist guanine quartet-mediated aggregation, yet form stable triplexes. Electrophoretic mobility shift and dimethyl sulfate footprinting assays were used to analyze the formation of triplexes Involving these oligonucleotide derivatives. In the absence of K+, all ODNs had similar binding affinities for the duplex target Triplexes involving a 14mer ODN derivative containing 7-deazaxanthine substituted for three thymine bases or an 18mer ODN containing two additional thymlnes on both the 5′ and 3′ termini were abolished by 50 mM K+. Remarkably, triplexes Involving an ODN derivative containing four 6-thloguanine bases substituted for guanine resisted K+ inhibition up to 200 mM. We hypothesize that the Increased radius and decreased electronegativity of sulfur in the 6-posltlon of guanine destabilize potential guanine quartets. These results improve the prospects for creating ODNs that might serve as specific and efficient gene repressors In vivo.
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U2 - 10.1093/nar/23.11.1936
DO - 10.1093/nar/23.11.1936
M3 - Article
C2 - 7596821
AN - SCOPUS:0029034982
SN - 0305-1048
VL - 23
SP - 1936
EP - 1941
JO - Nucleic acids research
JF - Nucleic acids research
IS - 11
ER -