Characterization and plant expression of a glyphosate-tolerant enolpyruvylshikimate phosphate synthase.
BACKGROUND
Glyphosate tolerance is a dominant trait in modern biotech crops.


RESULTS
A gene encoding a glyphosate-tolerant EPSP synthase (aroA(1398)) from bacterial strain ATX1398 was cloned and characterized. The protein is initiated at a GTG translational start codon to produce a protein that provides robust glyphosate resistance in Escherichia coli (Mig) Cast & Chalm. The aroA(1398) protein was expressed and purified from E. coli, and key kinetic values were determined (K(i) = 161 microM; K(m)(PEP) = 11.3 microM; k(cat) = 28.3 s(-1)). The full-length enzyme is 800-fold more resistant to glyphosate than the maize EPSP synthase while retaining high affinity for the substrate phosphoenol pyruvate. To evaluate further the potential of aroA(1398), transgenic maize events expressing the aroA(1398) protein were generated. T(0) plants were screened for tolerance to glyphosate sprays at 1.3x commercial spray rates, and T(1) plants were selected that completely resisted glyphosate sprays at 1x, 2x and 4x recommended spray rates in field trials.


CONCLUSIONS
These data suggest that aroA(1398) is a suitable candidate for conferring glyphosate tolerance in transgenic crop plants.
Vande Berg
Brian J
BJ
Athenix Corp., 108 TW Alexander Drive, Research Triangle Park, NC 27709, USA.
Hammer
Philip E
PE
Chun
Betty L
BL
Schouten
Laura C
LC
Carr
Brian
B
Guo
Rong
R
Peters
Cheryl
C
Hinson
Todd K
TK
Beilinson
Vadim
V
Shekita
Amy
A
Deter
Rebekah
R
Chen
Zhixian
Z
Samoylov
Vladimir
V
Bryant
Charles T
CT
Stauffer
Maria E
ME
Eberle
Timothy
T
Moellenbeck
Dan J
DJ
Carozzi
Nadine B
NB
Koziel
Mike G
MG
Duck
Nicholas B
NB
D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005998:Glycine / Q000031:analogs & derivatives*; D053209:Herbicide Resistance / Q000235:genetics; D006540:Herbicides; D007700:Kinetics; D030821:Plants, Genetically Modified / Q000201:enzymology*; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics; D000097797:Glyphosate
D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D005998:Glycine; D006540:Herbicides; D000097797:Glyphosate