Abstract: Ordered assembly of large numbers of fragments into a single large DNA have been improved in both frequency and fidelity of the assembled product. This has been achieved by novel compositions and methods that are utilized in a computer system that integrates comprehensive ligation data from multiple sources to provide optimized synthetic overhangs or overhangs from restriction endonuclease cleavage on DNA fragments for assembly by ligation. Intragenic cut sites are avoided by the use of a novel restriction endonuclease which recognizes 7 nucleotides (bases) and cuts DNA to create 4-base overhangs with the help of a synthetic activator oligonucleotide. Variations in ligation preferences by different ligases provide extra precision in assembly reactions. The use of the improved methods are exemplified by the successful assembly from 52 fragments of a viral genome and also a 52 fragment ordered assembly of a bacteria operon.

Abstract: A composition and its uses and additionally a kit are provided. The composition is a synthetic self-complementary oligonucleotide that has a double-stranded region and a loop, wherein the double-stranded region contains a binding sequence for PaqCl. Additionally, the oligonucleotide includes unligatable 3? and 5? ends that cannot be cleaved by PaqCl. This oligonucleotide composition has been combined with PaqCl or a variant of PaqCl Type IIS restriction endonuclease in a reaction mixture, where the reaction mixture includes PaqCl or variant that can further be combined with a ligase and optionally a deadenylase, crowding molecule such as PEG and/or a repair enzyme such as Endo MS. The kit includes the oligonucleotide and Type IIS restriction endonuclease in the same or different containers.