The research team “Synthetic Genomics”, led by Prof. TIAN Jingdong, has established an error correction reaction (ECR) employing Surveyor, a mismatch-specific DNA endonuclease, to remove errors from synthetic genes. The corresponding paper was published in Nucleic Acids Research. (http://nar.oxfordjournals.org/content/40/3/e23.long)

The development of economical and high-throughput gene synthesis technology has been hampered by the high occurrence of errors in the synthesized products, which requires expensive labor and time to correct. In this work, TIAN’s group provide detailed characterization of the molecular mechanism of the Surveyor-based error correction reaction (ECR) and the development of an optimized ECR protocol, which further reduced the error rate down to 1 error in ~8700 bp.

Fig. Outline of steps involved in error correction of synthetic DNA constructs. Gene synthesis products are heat denatured and then slowly cooled down to form heteroduplexes containing mismatches at the error sites (left panel). Heteroduplexes are cleaved by the Surveyor nuclease at the sites flanking the mismatch bulges. The resulting single-stranded overhangs, where mismatch bases are located, are removed by the proofreading exonuclease activity of Phusion polymerase used in the overlapping extention PCR (OE-PCR). The resulting fragments with mismatch bases removed are efficiently assembled back into full-length gene constructs during OE-PCR (right panel). (by Prof. TIAN’s group)