Abstract: This disclosure describes modified methods and compositions of matter pertaining to mate pair sequencing. In an implementation of the invention, mate pair sequence data is generated without cloning in a host system. In an implementation of the invention, a nucleic acid fragment is ligated into a vector. The vector containing the inserted nucleic acid fragment is digested with a restriction endonuclease that cuts at two or more places on the insert but does not cut the vector. Following the restriction endonuclease digest, the vector with portions of the nucleic acid fragment remaining after the restriction endonuclease digestion is again ligated. This ligation connects the cut ends of the insert to each other. The re-ligated product may be sequenced to obtain sequence data for both a “right” and “left” side of the originally inserted nucleic acid fragment.