Pigment-protein architecture in the light-harvesting antenna complexes of purple bacteria: does the crystal structure reflect the native pigment-protein arrangement?
D. Leupold et al., Pigment-protein architecture in the light-harvesting antenna complexes of purple bacteria: does the crystal structure reflect the native pigment-protein arrangement?, FEBS LETTER, 480(2-3), 2000, pp. 73-78
Structural analysis of crystallized peripheral (LH2) and core antenna compl
exes (LH1) of purple bacteria has revealed circular aggregates of high rota
tional symmetry (C-8, C-9 and C-16, respectively). Quantum-chemical calcula
tions indicate that in particular the waterwheel-like arrangements of pigme
nts should show characteristic structure-sensitive spectroscopic behavior i
n the near infrared absorption region. Laser-spectroscopic data obtained wi
th non-crystallized, isolated LH2 of Rhodospirillum molischianum are in lin
e with a highly symmetric (C8) circular aggregate, but deviations have been
found for LH2 of Rhodobacter sphaeroides and Rhodopseudomonas acidophila.
For both the latter, C-shaped incomplete circular aggregates (as seen only
recently in electron micrographs of crystallized LH1-reaction center comple
xes) may be a suitable preliminary model. (C) 2000 Federation of European B
iochemical Societies. Published by Elsevier Science B,V, All rights reserve
d.