Use of zinc ions to study thylakoid protein phosphorylation and the state 1-state 2 transition in vitro
At ATP concentrations less than 0.2 millimolar, zinc ions cause a marked stimulation of endogenous protein phosphorylation in thylakoid membranes isolated from tobacco (Nicotiana tabacum L. cv Turkish Samsun), pea (Pisum sativum L. cv Feltham First) and spinach (Spinacia oleracea L. cv Northland). The greatest stimulatory effect was observed at Zn/sup 2 +/ concentrations of 1 to 2 millimolar; higher concentrations were inhibitory. The stimulatory effect of Zn/sup 2 +/ was independent of Mg/sup 2 +/ concentration from 1 to 5 millimolar and thus does not appear to be due to the formation of a Zn/sup 2 +/-ATP complex. Phosphorylation of the histones IIA, an exogenous protein substrate, was inhibited by 2 millimolar Zn/sup 2 +/. At low levels of ATP, Zn/sup 2 +/ not only stimulates general endogenous protein phosphorylation, but also the phosphorylation of the apoproteins of the light-harvesting chlorophyll a/b-protein complex. However, under these conditions Zn/sup 2 +/ inhibits the ATP-induced quenching of photosystem II fluorescence and the increase in the ratio of photosystem I to photosystemII fluorescence which are both characteristic of the State 1-State 2 transition. These results suggest that phosphorylation of the light-harvesting chlorophyll a/b-protein complex may not directly bring about the State 1-State 1 transition.
- Research Organization:
- Univ. of Nebraska, Lincoln, NE (United States)
- OSTI ID:
- 6577765
- Journal Information:
- Plant Physiol.; (United States), Vol. 74:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
14 SOLAR ENERGY
PROTEINS
PHOSPHORYLATION
ZINC
BIOLOGICAL EFFECTS
ATP
CHLOROPHYLL
IN VITRO
IN VIVO
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PISUM
TOBACCO
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
ELEMENTS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
LEGUMINOSAE
METALS
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYTOCHROMES
PIGMENTS
PLANTS
PORPHYRINS
SYNTHESIS
560303* - Chemicals Metabolism & Toxicology- Plants- (-1987)
140505 - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)