U. Johanningmeier et al., Herbicide resistance and supersensitivity in Ala(250) or Ala(251) mutants of the D1 protein in Chlamydomonas reinhardtii, PEST BIOCH, 66(1), 2000, pp. 9-19
Various site-directed mutants at position Ala(250) or Ala(251) within the h
erbicide-binding niche of the D1 subunit of photosystem II were generated b
y transforming a Chlamydomonas reinhardtii strain specifically engineered t
o lack a psbA gene fragment coding for the binding region. The following mu
tants were obtained: Asp(250), Phe(250), His(250), Ile(250), Asn(250), Arg(
250), Tyr(250), Cys(251), Gly(251), and the double mutant Ser(250)/Ile(255)
. A variety of herbicides and inhibitors, such as s-triazines, phenolic her
bicides, p-benzo- and naphthoquinones, acridones, a NH-thiazol, and phenmed
ipham, were assayed for their inhibitory activity in these mutants. In addi
tion, in the Ser(250)/Ile(255) mutant 32 different triazinones were tested
for biological activity. In all mutants, either resistance and/or supersens
itivity against the herbicides and inhibitors was observed. The resistance
and/or supersensitivity against inhibitors in the Ala(250) mutants demonstr
ated for the first time the involvement of this amino acid in herbicide bin
ding. (C) 2000 Academic Press.