Carotenoids are essential for normal levels of dimerisation of the RC-LH1-PufX core complex of Rhodobacter sphaeroides: Characterisation of R-26 as a crtB (phytoene synthase) mutant

Journal Article · · Biochimica et Biophysica Acta - Bioenergetics

DOI:https://doi.org/10.1016/j.bbabio.2011.05.020· OSTI ID:1065570

Ng, Irene W. ^[1]; Adams, Peter G. ^[1]; Mothersole, David J. ^[1]; Vasilev, Cvetelin ^[1]; Martin, Elizabeth C. ^[1]; Lang, Helen P. ^[1]; Tucker, Jaimey D. ^[1]; Hunter, C. Neil ^[1]

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1. Univ. of Sheffield (United Kingdom). Dept. of Molecular Biology and Biotechnology

Carotenoids play important roles in photosynthesis where they are involved in light-harvesting, in photo-protection and in the assembly and structural stability of light-harvesting and reaction centre complexes. In order to examine the effects of carotenoids on the oligomeric state of the reaction centre–light-harvesting 1 -PufX (RC–LH1–PufX) core complex of Rhodobacter sphaeroides two carotenoid-less mutants, TC70 and R-26, were studied. Detergent fractionation showed that in the absence of carotenoids LH2 complexes do not assemble, as expected, but also that core complexes are predominantly found as monomers, although levels of the PufX polypeptide appeared to be unaffected. Analysis of R-26 membranes by electron microscopy and atomic force microscopy reveals arrays of hexagonally packed monomeric RC–LH1–PufX complexes. Transfer of the crtB gene encoding phytoene synthase to TC70 and R-26 restores the normal synthesis of carotenoids demonstrating that the R-26 mutant of Rba. sphaeroides harbours a mutation in crtB, among its other defects. The transconjugant TC70 and R-26 strains containing crtB had regained their ability to assemble wild-type levels of dimeric RC–LH1–PufX core complexes and normal energy transfer pathways were restored, demonstrating that carotenoids are essential for the normal assembly and function of both the LH2 and RC–LH1–PufX complexes in this bacterial photosystem.

• Research Organization: Energy Frontier Research Centers (EFRC); Photosynthetic Antenna Research Center (PARC)
• Sponsoring Organization: USDOE SC Office of Basic Energy Sciences (SC-22)
• DOE Contract Number: SC0001035
• OSTI ID: 1065570
• Journal Information: Biochimica et Biophysica Acta - Bioenergetics, Journal Name: Biochimica et Biophysica Acta - Bioenergetics Journal Issue: 9 Vol. 1807; ISSN 0005-2728
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
solar (fuels)
photosynthesis (natural and artificial)
biofuels (including algae and biomass)
bio-inspired
charge transport
membrane
synthesis (novel materials)
synthesis (self-assembly)