10
A. Trebst
Fig. 1.3. Amino acids in the Dl protein involved in OB binding. Only two of the
transmembrane helices, a parallel helix and the interconnecting sequence are of immediate
significance for OB and for herbicide binding. They are identified by amino acid substitutions in herbicide-tolerant plants with point mutation in the psbA gene and by
photoaffinity labeling. In the extended loop between transmembrane helix 4 and the
parallel helix, a specific easily accessible trypsin cut at arg238 and a proposed cleavage site
and a protease-recognizing PEST sequence in rapid turnover of the Dl protein are
indicated
dependence of the cross-resistance of herbicides on the size of substituents
in the chemical structure of the herbicides in various mutants of Chlamydomonas rh., isolated by screening against just one herbicide (Rochaix
and Erickson 1988), allowed the refining at the folding model by computer
analysis (Draber et al. 1991). Recently, this was possible also for phenol
type herbicides (Draber et al. 1993).
Some of the amino acids involved in the QB and herbicide-binding niche
are in a part of the sequence of the D1 protein that is called the extended
loop. This is because about 14 amino acids between transmembrane helix IV
and the parallel helix (see Figs. 1.2, 1.3) are not present in the L subunit of
purple bacteria, whose QB site is otherwise very homologous to that of the
A. Trebst
Fig. 1.3. Amino acids in the Dl protein involved in OB binding. Only two of the
transmembrane helices, a parallel helix and the interconnecting sequence are of immediate
significance for OB and for herbicide binding. They are identified by amino acid substitutions in herbicide-tolerant plants with point mutation in the psbA gene and by
photoaffinity labeling. In the extended loop between transmembrane helix 4 and the
parallel helix, a specific easily accessible trypsin cut at arg238 and a proposed cleavage site
and a protease-recognizing PEST sequence in rapid turnover of the Dl protein are
indicated
dependence of the cross-resistance of herbicides on the size of substituents
in the chemical structure of the herbicides in various mutants of Chlamydomonas rh., isolated by screening against just one herbicide (Rochaix
and Erickson 1988), allowed the refining at the folding model by computer
analysis (Draber et al. 1991). Recently, this was possible also for phenol
type herbicides (Draber et al. 1993).
Some of the amino acids involved in the QB and herbicide-binding niche
are in a part of the sequence of the D1 protein that is called the extended
loop. This is because about 14 amino acids between transmembrane helix IV
and the parallel helix (see Figs. 1.2, 1.3) are not present in the L subunit of
purple bacteria, whose QB site is otherwise very homologous to that of the