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1987 (1)
1Author    WimF J Vermaas, JohnG K Williams, CharlesJ. ArntzenRequires cookie*
 Title    Site-Directed Mutations of Two Histidine Residues in the D 2 Protein Inactivate and Destabilize Photosystem II in the Cyanobacterium Synechocystis 6803  
 Abstract    Site-directed m utations were created in the cyanobacterium Synechocystis 6803 to alter specific histidine residues o f the photosystem II (PS II) D 2 protein. In one mutant (tyr-197). the his-197 residue was replaced by tyrosine, in another mutant (asn-214), his-214 was changed into asparagine. The tyr-197 mutant did not show any low-tem perature fluorescence attributable to PS II. but contained a PS II chlorophyll-protein, CP-47, in significant quantities. A nother PS II chlorophyll-protein, CP-43, was absent, as was PS II-related herbicide binding. The asn-214 mutant showed a blue-shifted low-temperature fluorescence maximum around 682 nm. but did not have a significant amount of membrane-incorporated CP-43 or CP-47. Herbicide binding was also absent in this mutant. These data indicate a very important role o f the his-197 and his-214 residues in the D 2 protein, and are interpreted to support the hypothesis that the D 2 protein and the M subunit from the photosynthetic reaction center of purple bacteria have analogous func­ tions. According to this hypothesis, his-197 is involved in binding of P680. and his-214 forms ligands with Q A and Fe:+. In absence o f a functional D 2 protein, the PS II core com plex appears to be destabilized as evidenced by loss o f chlorophyll-proteins in the mutants. 
  Reference    Z. Naturforsch. 42c, 762—768 (1987); received D ecem ber 30 1986 
  Published    1987 
  Keywords    Site-D irected M utagenesis, Herbicide Binding, Photosystem II Proteins, Photosynthesis, Cyanobacteria 
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 TEI-XML for    default:Reihe_C/42/ZNC-1987-42c-0762.pdf 
 Identifier    ZNC-1987-42c-0762 
 Volume    42