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'Herbicide Resistance' in keywords Facet   Publication Year 1990  [X]
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1Author    Nir Ohad3, Dekel Amir-Shapirab, Hiroyuki Koikec, Yorinao Inouec, Itzhak Ohadb, Joseph Hirschberg3Requires cookie*
 Title    Amino Acid Substitutions in the D 1 Protein of Photosystem II Affect Q b-Stabilization and Accelerate Turnover of D  
 Abstract    Isogenic strains of Synechococcus PCC 7942 were genetically engineered so that copy I of the gene psbA was mutated at specific sites. These mutations resulted in replacements of Ser 264 by Gly or Ala and of Phe 255 by Tyr or Leu in the D 1 protein. The mutants were resistant to herbicides inhibiting electron transfer in photosystem II. All mutants exhibited alterations in the stability of Q B' as demonstrated by a temperature downshift, to various extents, of the in vivo thermoluminescence emission. Measurements of the light-dependent turnover of D 1 showed a marked decrease in the 11 / 2 of this protein in the mutants as compared to wild-type, under low to medium light intensities. A correlation was found between the degree of pertur­ bation in the Q B" stability and the rate of acceleration in the turnover of D 1. These data pro­ vide a direct evidence for the overlapping binding sites for the plastoquinone B and herbicides in the D 1 protein. In addition these data indicate a close link between Q B" destabilization in reaction center II and the mechanism controlling the light-dependent turnover of D 1. Based on these results and previous work we suggest that destabilization of the semireduced quinone, facilitates a light-induced damage in D 1 which triggers its degradation. 
  Reference    Z. Naturforsch. 45c, 402—408 (1990); received November 21 1989 
  Published    1990 
  Keywords    Herbicide Resistance, Thermoluminescence, D 1 Turnover, Synechococcus PCC 7942 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0402.pdf 
 Identifier    ZNC-1990-45c-0402 
 Volume    45 
2Author    I. Sinning, J. Koepke, B. Schiller, H. MichelRequires cookie*
 Title    First Glance on the Three-Dimensional Structure of the Photosynthetic Reaction Center from a Herbicide-Resistant Rhodopseudomonas viridis Mutant  
 Abstract    A first model o f the three-dimensional structure o f the photosynthetic reaction center o f the mutant T1 (SerL223 —* ■ Ala, ArgL217 —* His) from Rhodopseudom onas viridis, resistant to ­ ward the triazine herbicide terbutryn (2-m ethylthio-4-ethylam ino-6-/-butylam ino-s-triazine), has been developed from X-ray data measured to a resolution o f 2.5 Ä. The secondary qui­ none, Q B, which in T 1 binds better than in the wild type, is present in the crystals. Both substi­ tuted residues are clearly visible in the difference fourier map. The replacement o f these two residues in the Q B site causes only minor changes in the overall structure o f the protein. 
  Reference    Z. Naturforsch. 45c, 455 (1990); received December 9 1989 
  Published    1990 
  Keywords    Three-Dimensional Structure, Herbicide Resistance, Terbutryn, Photosynthetic Reaction Center 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0455.pdf 
 Identifier    ZNC-1990-45c-0455 
 Volume    45