Phenylamide polymerase activity

Likewise, endogenous polymerase activity of isolated nuclei from these strains is significantly less sensitive to phenylamides than that of nuclei from sensitive strains (Table IV). This indicates that in both species a change in the target site of metalaxyl is responsible for resistance. Apparently both mutagen induced... 

Table IV. Effect of Phenylamides (1 pg/ml) on Endogenous RNA Polymerase Activity of Nuclei isolated from a Phenylamide-Sensitive (S) and a Phenylamide-Resistant (R) Strain of...

Phenylamide fungicides selectively inhibit ribosomal RNA synthesis of sensitive Oomycete fungi by interference with the activity of the RNA polymerase I-template complex. 

Although binding activity could be easily demonstrated in crude cell free mycelial extracts of phenylamide-sensitive Phytophthora strains, binding activity decreased considerably when the extracts were subjected to Heparin Sepharose affinity chromatography, a first step in the purification of RNA polymerases (16. Purification of the phenylamide receptor, therefore, cannot be followed using the binding assay. An alternative approach would be to covalently label the receptor with a photoaffinity probe. Purification of the labeled complex can then be followed either by a radioassay or an immunoassay, which respectively require a radiolabeled photoaffinity probe or antiserum that selectively recognizes covalently bound phenylamide residues. 

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