Zeitschrift fuer Naturforschung. Section C 1990-05-01

A new ioxynil-resistant mutant in Synechocystis PCC 6714: hypothesis on the interaction of ioxynil with the D 1 protein.

S Creuzet, G Ajlani, C Vernotte, C Astier

Index: Z. Naturforsch., C, J. Biosci. 45(5) , 436-40, (1990)

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Abstract

A new Synechocystis 6714 mutant, IoxIIA, resistant to the phenol-type herbicide ioxynil was isolated and characterized. The mutation found in the psbA gene (encoding the D 1 photosystem II protein) is at the same codon 266 as for the first ioxynil-resistant mutant IoxIA previously selected [G. Ajlani, I. Meyer, C. Vernotte, and C. Astier, FEBS Lett. 246, 207-210 (1989)]. In IoxIIA, the change of Asn 266 to Asp gives a 3 x resistance, whereas in IoxIA, the change of the same amino acid to Thr gives a 10 x resistance. The effect of these different amino acid substitutions on the ioxynil resistance phenotype has allowed us to construct molecular models and calculate the hydrogen-bonding energies between the hydroxyl group of ioxynil and the respective amino acids at position 266.