Efficient unwinding of triplex DNA by a DNA helicase.
Sequence specific triple helix formation shows promise as a strategy for gene-specific inhibition of gene expression by blocking promoters or enhancers. Therefore, it is important to understand how this unusual structure affects DNA metabolic processes other than transcription. It has been shown that triplexes block in vitro DNA synthesis catalyzed by purified DNA polymerases. We report here that a purified DNA helicase unwinds a triple helical substrate with an efficiency similar to that observed with a comparable duplex species. These model studies suggest that triple helices will not seriously inhibit DNA replication or recombination in vivo, since DNA polymerases are preceded by helicases in the fully assembled replication holoenzyme.
Department of Chemistry and Biochemistry, University of Texas at Austin 78712.
I P
IP
Maine
T
T
Kodadek
D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004265:DNA Helicases / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D014764:Viral Proteins
D009838:Oligodeoxyribonucleotides; D014764:Viral Proteins; D004247:DNA; D004265:DNA Helicases; C077401:dda DNA helicase protein, Bacteriophage T4