PLANT PHYSIOLOGY , Vol 109, Issue 1 153-159, Copyright © 1995 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
Insect Cell Expression of Recombinant Imidazoleglycerolphosphate Dehydratase of Arabidopsis and Wheat and Inhibition by Triazole Herbicides
S. Tada, M. Hatano, Y. Nakayama, S. Volrath, D. Guyer, E. Ward and D. Ohta
International Research Laboratories, Ciba-Geigy Japan Ltd., P.O. Box 1, Takarazuka 665, Japan (S.T., M.H., Y.N., D.O.)
Imidazoleglycerolphosphate dehydratase (IGPD; EC 4.2.1.19), which is
involved in the histidine biosynthetic pathway of Arabidopsis thaliana and
wheat (Triticum aestivum), has been expressed in insect cells using the
baculovirus expression vector system. N-terminal amino acid sequencing
indicated that recombinant IGPDs (rIGPDs) were produced as mature forms via
nonspecific proteolytic cleavages in the putative transit peptide region.
The wheat rIGPD contained one Mn atom per subunit, and the Mn was involved
in the assembly of the subunits to form active IGPDs. Protein-blotting
analysis, using antibodies raised against the wheat rIGPD, indicated that
IGPD was located in the chloroplasts of wheat. The rIGPDs of Arabidopsis
and wheat, which were 86% identical in their primary structures deduced
from the cDNAs, exhibited similar properties in terms of the molecular
mass, pH optimum, and the Km for the substrate, imidazoleglycerolphosphate.
However, the nonselective herbicides 3-amino-1,2,4-triazole and a newly
synthesized triazole [(1R*,
3R*)-[3-hydroxy-3-(2H-[1,2,4]triazole-3-yl)-cyclohexyl]-phosphonic acid],
inhibited Arabidopsis and wheat IGPDs in a mixed-type and a competitive
manner, respectively.