Method of Nucleic Acid Recombination

The invention provides a method for inserting a single stranded replacement nucleic acid into a target nucleic acid, said method comprising the steps of: a) generating a single stranded replacement nucleic acid from a double stranded nucleic acid, wherein the double stranded nucleic acid is adapted at one or both of its 5′ ends such that preferential degradation of one strand and/or strand separation generates the single stranded replacement nucleic acid, wherein the single stranded replacement nucleic acid comprises a 5′ region that is identical to sequence on the target nucleic acid, a 3′ region that is identical to sequence on the target nucleic acid and optionally a replacement region between the 5′ and 3′ regions that is not identical to sequence on the target N nucleic acid, b) exposing the target nucleic acid to the single stranded replacement nucleic acid under conditions suitable for recombination to occur between the single stranded replacement nucleic acid and the target nucleic acid, and c) selecting a target nucleic acid whose sequence has been altered by inclusion of said single stranded replacement nucleic acid. Other methods for modifying target nucleic acids are also provided.