RT Journal Article SR Electronic T1 Discovery and Directed Evolution of a Glyphosate Tolerance Gene JF Science JO Science FD American Association for the Advancement of Science SP 1151 OP 1154 DO 10.1126/science.1096770 VO 304 IS 5674 A1 Castle, Linda A. A1 Siehl, Daniel L. A1 Gorton, Rebecca A1 Patten, Phillip A. A1 Chen, Yong Hong A1 Bertain, Sean A1 Cho, Hyeon-Je A1 Duck, Nicholas A1 Wong, James A1 Liu, Donglong A1 Lassner, Michael W. YR 2004 UL http://science.sciencemag.org/content/304/5674/1151.abstract 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.