Biochemical basis of resistance to phenylamide fungicides
1990
Davidse, L.C.
Phenylamide fungicides selectively inhibit ribosomal RNA synthesis of sensitive Oomycete fungi by interference with the activity of the RNA polymerase I-template complex. Phenylamides bind to an as yet unidentified component of this complex. The phenylamide binding site in resistant strains has a very low affinity for metalaxyl, whereas values of the dissociation constant are in the order of 0.1-0.2 micromolar for phenylamidesensitive strains. Apparently a change at the phenylamide receptor is responsible for resistance. Identification of the phenylamide receptor is hampered by loss of its ability to bind phenylamides during purification. To overcome this a photoaffinity probe for the phenylamide receptor has been synthesized. The biological properties of this probe allow its use to tag the components of the enzyme complex involved in binding.
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