PT - JOURNAL ARTICLE AU - Castle, Linda A. AU - Siehl, Daniel L. AU - Gorton, Rebecca AU - Patten, Phillip A. AU - Chen, Yong Hong AU - Bertain, Sean AU - Cho, Hyeon-Je AU - Duck, Nicholas AU - Wong, James AU - Liu, Donglong AU - Lassner, Michael W. TI - Discovery and Directed Evolution of a Glyphosate Tolerance Gene AID - 10.1126/science.1096770 DP - 2004 May 21 TA - Science PG - 1151--1154 VI - 304 IP - 5674 4099 - http://science.sciencemag.org/content/304/5674/1151.short 4100 - http://science.sciencemag.org/content/304/5674/1151.full SO - Science2004 May 21; 304 AB - The herbicide glyphosate is effectively detoxified by N-acetylation. We screened a collection of microbial isolates and discovered enzymes exhibiting glyphosate N-acetyltransferase (GAT) activity. Kinetic properties of the discovered enzymes were insufficient to confer glyphosate tolerance to transgenic organisms. Eleven iterations of DNA shuffling improved enzyme efficiency by nearly four orders of magnitude from 0.87 mM–1 min–1 to 8320 mM–1 min–1. From the fifth iteration and beyond, GAT enzymes conferred increasing glyphosate tolerance to Escherichia coli, Arabidopsis, tobacco, and maize. Glyphosate acetylation provides an alternative strategy for supporting glyphosate use on crops.