ISSN:
1573-5028
Keywords:
bean
;
leaf senescence
;
protein degradation
;
protein synthesis
;
thylakoids
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract During senescence of primary bean leaves (Phaseolus vulgaris), there are differential changes in the rates at which thylakoid proteins are synthesized. In particular, synthesis of the 32 kD herbicide-binding protein continues throughout senescence, whereas formation of the α and β subunits of ATPase, the 68 kD photosystem I reaction center polypeptide, cytochrome f, cytochrome b6 and the structural apoprotein of the lightharvesting chlorophyll protein complex (LHCP) declines. Pulse-chase experiments with intact leaves indicated rapid degradation of the 32 kD protein, which is consistent with its known rapid rate of turnover. This degradation was light-dependent and inhibited by DCMU, and the kinetics of degradation were similar for young and senescent membranes. In Coomassie-stained gels, the 68 kD reaction center polypeptide of photosystem I, the α and β subunits of ATPase and the LHCP were the dominant proteins for all ages of membranes. Western blot analysis indicated that cytochrome f and cytochrome b6 are selectively depleted during senescence. The data have been interpreted as indicating that translational disruptions in both the cytoplasmic and chloroplastic compartments may contribute to the decline in photosynthetic electron transport in the senescing leaf.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00014909
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