Photosynthetic water oxidation in Synechocystis sp. PCC6803: mutations D1-E189K, R and Q are without influence on electron transfer at the donor side of photosystem II.

Content Provider	Semantic Scholar
Author	Clausen, Juergen Winkler, Sonja Hays, A. R. Marshalift P. B. Hundelt, Monika Debus, Richard J. Junge, Wolfgang
Copyright Year	2001
Abstract	The oxygen-evolving manganese cluster (OEC) of photosynthesis is oxidised by the photochemically generated primary oxidant (P(+*)(680)) of photosystem II via a tyrosine residue (Y(Z), Tyr161 on the D1 subunit of Synechocystis sp. PCC6803). The redox span between these components is rather small and probably tuned by protonic equilibria. The very efficient electron transfer from Y(Z) to P(+*)(680) in nanoseconds requires the intactness of a hydrogen bonded network involving Y(Z), D1-His190, and presumably D1-Glu189. We studied photosystem II core particles from photoautotrophic mutants where the residue D1-E189 was replaced by glutamine, arginine and lysine which were expected to electrostatically differ from the glutamate in the wild-type (WT). Surprisingly, the rates of electron transfer from Y(Z) to P(+*)(680) as well as from the OEC to Y(ox)(Z) were the same as in the WT. With the generally assumed proximity between D1-His190 (and thus D1-Glu189) and Y(Z), the lack of any influence on the electron transfer around Y(Z) straightforwardly implies a strongly hydrophobic environment forcing Glu (acid) and Lys, Arg (basic) at position D1-189 into electro-neutrality. As one alternative, D1-Glu189 could be located at such a large distance from the OEC, Y(Z) and P(+*)(680) that a charge on D1-189X does not influence the electron transfer. This seems less likely in the light of the drastic influence of its direct neighbour, D1-His190, on Y(Z) function. Another alternative is that D1-Glu189 is negatively charged, but is located in a cluster of acid/base groups that compensates for an alteration of charge at position 189, leaving the overall net charge unchanged in the Gln, Lys, and Arg mutants.
Starting Page	1011
Ending Page	1018
Page Count	8
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://www.home.uni-osnabrueck.de/wjunge/public/227.pdf
PubMed reference number	11779556v1
Volume Number	1506
Issue Number	3
Journal	Biochimica et biophysica acta
Language	English
Access Restriction	Open
Subject Keyword	Arginine Assumed BAM 22P Charge (electrical) Departure - action Ephrin Type-B Receptor 1, human Glutamic Acid Glutamine Lysine Mutation Oxidants Oxygen Photosynthesis Photosystem II Span Distance Synechocystis Tyrosine Water 1000 MG/ML Injectable Solution mutant oxidation respiratory electron transport chain process
Content Type	Text
Resource Type	Article