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

DOI: 10.1042/BJ20110575 DOI Help

Authors: Tatas H. P. Brotosudarmo (University of Glasgow) , Aaron M. Collins (Washington University in St. Louis) , Andrew Gall (Institute de Biologie et Technologies de Saclay et CNRS/URA2096) , Aleksander W. Roszak (University of Glasgow) , Alastair T. Gardiner (University of Glasgow) , Robert E. Blankenship (University in St. Louis) , Richard J. Cogdell (University of Glasgow)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Biochemical Journal

State: Published (Approved)
Published: July 2011

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 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.

Journal Keywords: Purple photosynthetic bacteria; Rhodospeudomonas palustris; light harvesting complexes; X-ray crystallography; puc genes

Subject Areas: Biology and Bio-materials

Instruments: I04-Macromolecular Crystallography

Other Facilities: European Synchrotron Radiation Facility