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/lp/portland-press/the-light-intensity-under-which-cells-are-grown-controls-the-type-of-5hkjt0gztT
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- Publisher
- Portland Press
- Copyright
- Copyright by Portland Press
- ISSN
- 0264-6021
- DOI
- 10.1042/BJ20110575
- pmid
- 21793805
- Publisher site
- See Article on Publisher Site
Abstract
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 PucAB a and PucAB b apoproteins. The LL complexes contain PucAB a , PucAB d and PucB b -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.
Journal
Biochemical Journal – Portland Press
Published: Nov 15, 2011
Keywords: bacteriochlorophyll, light-harvesting complex, puc gene, purple photosynthetic bacterium, Rhodopseudomonas palustris, X-ray crystallography