Patent ID: 6653106
Filing Date: 2003-11-25
Classification: C07H,C12N,C12Y

Abstract:
A method for covalently joining a DNA strand and an RNA strand, the method comprising:(a) contacting a sequence-specific type I DNA topoisomerase in vitro with a double-stranded DNA whose first strand is to be covalently joined to the RNA strand, wherein the first strand comprises a recognition sequence for the type I topoisomerase at a site whose complement on the second strand is located 3â€² of the 5â€² terminus of the second strand, so as to permit the topoisomerase to bind to the DNA and cleave the first strand thereof, thereby forming a topoisomerase/DNA complex wherein the DNA's second strand has a 5â€² tail; and (b) contacting the resulting complex in vitro with a 5â€² OH-containing RNA strand whose 5â€² terminal portion is complementary to the 3â€² terminal portion of the DNA 5â€² tail, under conditions permitting (i) the RNA strand to hybridize with the 5â€² tail and (ii) the topoisomerase to covalently join the RNA strand and first DNA strand, thereby covalently joining the DNA strand to the RNA strand.