Lambda phage DNA: joining of a chemically synthesized cohesive end.

The chemically synthesized dodecamer d(pA-G-G-T-C-G-C-C-G-C-C-C) was annealed, and was covalently joined to lambda phage DNA with bacterio-phage T(4) ligase. The 5'-end of the dodecamer was joined to a deoxyguanosine residue. Repair with DNA polymerase I established that the position of joining was the left-hand end of lambda DNA. This is the first time that a chemically synthesized oligonucleotide has been covalently joined to a naturally occurring DNA molecule.