scholarly journals The light intensity under which cells are grown controls the type of peripheral light-harvesting complexes that are assembled in a purple photosynthetic bacterium

2011 ◽  
Vol 440 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Tatas H. P. Brotosudarmo ◽  
Aaron M. Collins ◽  
Andrew Gall ◽  
Aleksander W. Roszak ◽  
Alastair T. Gardiner ◽  
...  
Keyword(s):  
Light Intensity ◽  
Light Harvesting ◽  
Rhodopseudomonas Palustris ◽  
Photosynthetic Bacterium ◽  
Low Light ◽  
Light Harvesting Complexes ◽  
Density Maps ◽  
Purple Photosynthetic Bacterium ◽  
Resonance Raman Spectra ◽  
Apoprotein Composition

The differing composition of LH2 (peripheral light-harvesting) complexes present in Rhodopseudomonas palustris 2.1.6 have been investigated when cells are grown under progressively decreasing light intensity. Detailed analysis of their absorption spectra reveals that there must be more than two types of LH2 complexes present. Purified HL (high-light) and LL (low-light) LH2 complexes have mixed apoprotein compositions. The HL complexes contain PucABa and PucABb apoproteins. The LL complexes contain PucABa, PucABd and PucBb-only apoproteins. This mixed apoprotein composition can explain their resonance Raman spectra. Crystallographic studies and molecular sieve chromatography suggest that both the HL and the LL complexes are nonameric. Furthermore, the electron-density maps do not support the existence of an additional Bchl (bacteriochlorophyll) molecule; rather the density is attributed to the N-termini of the α-polypeptide.

scholarly journals Low Light Adaptation: Energy Transfer Processes in Different Types of Light Harvesting Complexes from Rhodopseudomonas palustris

2009 ◽  
Vol 97 (11) ◽  
pp. 3019-3028 ◽  
Author(s):  
Vladimíra Moulisová ◽  
Larry Luer ◽  
Sajjad Hoseinkhani ◽  
Tatas H.P. Brotosudarmo ◽  
Aaron M. Collins ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Light Adaptation ◽  
Light Harvesting ◽  
Rhodopseudomonas Palustris ◽  
Low Light ◽  
Light Harvesting Complexes ◽  
Transfer Processes ◽  
Different Types

PHOTOACCLIMATION IN PHOTOSYNTHETIC MICROORGANISMS: AN ULTRASTRUCTURAL RESPONSE

1998 ◽  
Vol 46 (2) ◽  
pp. 141-146 ◽  
Author(s):  
Tamar Berner ◽  
Assaf Sukenik
Keyword(s):  
Light Intensity ◽  
Light Harvesting ◽  
Photosynthetic Apparatus ◽  
Typical Feature ◽  
Optimal Operation ◽  
High Irradiance ◽  
High Rate ◽  
Low Light ◽  
Low Light Intensity ◽  
Photosynthetic Microorganisms

Photosynthetic microorganisms are able to modify their chemical composition, cellular structure, and organization of their chloroplasts in response to the level of irradiance. The photosynthetic apparatus adjusts itself to any new light regime by changing the ultrastructural properties of the chloroplast to provide space and area needed to match other biochemical changes in order to optimize light harvesting and utilization. Acclimation to low light intensity is characterized by an increase in thylakoid number in cyanobacteria, and in the chloroplast volume in eukaryotic plants. In the Eukaryota, these changes allow the packaging of more thylakoids within this organelle to harbor the addition of photosynthetic complexes, i.e., light harvesting antennae, reaction centers, and electron transport components. These changes are essential for optimal operation of the photosynthetic apparatus at low light intensity, mainly to increase the absorption of light energy. Acclimation to high irradiance is characterized by a reduction of the surface density of thylakoid membranes and reduction in the specific volume of the chloroplast. The accumulation of storage bodies containing starch and lipids is yet another typical feature of high light acclimated cells in response to the high rate of photosynthetic activity.

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