Protein synthesis by isolated Acetabularia chloroplasts. In vitro synthesis of the apoprotein of the P-700-chlorophyll a-protein complex (CP I)

1980 ◽  
Vol 609 (1) ◽  
pp. 107-120 ◽  
Author(s):  
Beverley R Green
Keyword(s):  
Protein Synthesis ◽  
Chlorophyll A ◽  
Protein Complex ◽  
In Vitro Synthesis

scholarly journals Light-regulated translation of chloroplast proteins. I. Transcripts of psaA-psaB, psbA, and rbcL are associated with polysomes in dark-grown and illuminated barley seedlings

1988 ◽  
Vol 106 (2) ◽  
pp. 289-301 ◽  
Author(s):  
RR Klein ◽  
HS Mason ◽  
JE Mullet
Keyword(s):  
Chlorophyll A ◽  
Photosystem I ◽  
In Vitro Translation ◽  
Chain Elongation ◽  
Selective Activation ◽  
Translation Elongation ◽  
In Vitro Synthesis ◽  
Chloroplast Translation ◽  
Membrane Bound

We have previously observed (Klein, R. R., and J. E. Mullet, 1986, J. Biol. Chem. 261:11138-11145) that translation of two 65-70-kD chlorophyll a-apoproteins of Photosystem I (gene products of psaA and psaB) and a 32-kD quinone-binding protein of Photosystem II (gene product of psbA) was not detected in plastids of dark-grown barley seedlings even though transcripts for these proteins were present. In the present study it was found that nearly all of the psaA-psaB transcripts in plastids of dark-grown plants were associated with membrane-bound polysomes. Membrane-associated polysomes from plastids of dark-grown plants synthesized the 65-70-kD chlorophyll a-apoproteins at low levels when added to a homologous in vitro translation extract capable of translation elongation. However, when etioplast membranes were disrupted with detergent, in vitro synthesis of the 65-70-kD chlorophyll a-apoproteins increased to levels observed with polysomes of plastids from illuminated plants. These results suggest that synthesis of the chlorophyll a-apoproteins of Photosystem I is arrested on membrane-bound polysomes at the level of polypeptide chain elongation. In addition to the selective activation of chlorophyll a-apoprotein translation, illumination also caused an increase in chloroplast polysomes (membrane-associated and stromal) and induced a recruitment of psbA and rbcL transcripts into chloroplast polysomes. These results indicate that in conjunction with the selective activation of chlorophyll a-apoprotein elongation, illumination also caused a general stimulation of chloroplast translation initiation.

scholarly journals In vitro synthesis of chlorophyll a in the dark triggers accumulation of chlorophyll a apoproteins in barley etioplasts.

1990 ◽  
Vol 265 (23) ◽  
pp. 13566-13571
Author(s):  
L.A. Eichacker ◽  
J. Soll ◽  
P. Lauterbach ◽  
W. Rüdiger ◽  
R.R. Klein ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
In Vitro Synthesis

High-Resolution electron crystallography of the light-harvesting chlorophyll-a/b protein complex from chloroplast membranes

1990 ◽  
Vol 48 (1) ◽  
pp. 610-610
Author(s):  
Werner Kühlbrandt ◽  
Da Neng Wang ◽  
K.H. Downing
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Chlorophyll A ◽  
Protein Complex ◽  
Structural Integrity ◽  
Light Harvesting ◽  
Lhc Ii ◽  
Diffraction Patterns ◽  
Difference Fourier ◽  
2D Crystals

The light-harvesting chlorophyll-a/b protein complex (LHC-II) is the most abundant membrane protein in the chloroplasts of green plants where it functions as a molecular antenna of solar energy for photosynthesis. We have grown two-dimensional (2d) crystals of the purified, detergent-solubilized LHC-II . The crystals which measured 5 to 10 μm in diameter were stabilized for electron microscopy by washing with a 0.5% solution of tannin. Electron diffraction patterns of untilted 2d crystals cooled to 130 K showed sharp spots to 3.1 Å resolution. Spot-scan images of 2d crystals were recorded at 160 K with the Berkeley microscope . Images of untilted crystals were processed, using the unbending procedure by Henderson et al . A projection map of the complex at 3.7Å resolution was generated from electron diffraction amplitudes and high-resolution phases obtained by image processing .A difference Fourier analysis with the same image phases and electron diffraction amplitudes recorded of frozen, hydrated specimens showed no significant differences in the 3.7Å projection map. Our tannin treatment therefore does not affect the structural integrity of the complex.

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