The peripheral light-harvesting complexes from purple sulfur bacteria have different 'ring' sizes.
The integral membrane light-harvesting (LH) proteins from purple photosynthetic bacteria form circular oligomers of an elementary unit that is composed of two very hydrophobic polypeptides, termed alpha and beta. These apoprotein dimers are known to associate into closed circular arrays of 8, 9 and 16 alpha/beta-mers. We report the existence of peripheral LH proteins purified from Allochromatium vinosum with two intermediate ring sizes and postulate that one is a 13 alpha/beta-mer. This shows that LH proteins are able to form membrane rings of continuously increasing diameter from 68 to 115A. The presence of these new ring sizes warrants further study, as it will help to further validate the structure-function models of LH proteins currently found in the literature.
Department of Biophysical Chemistry, Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Sami
S
Kereïche
Laurent
L
Bourinet
Wilko
W
Keegstra
Ana A
AA
Arteni
Jean-Marc
JM
Verbavatz
Egbert J
EJ
Boekema
Bruno
B
Robert
Andrew
A
Gall
D002841:Chromatiaceae / Q000201:enzymology*; D020285:Cryoelectron Microscopy; D019281:Dimerization; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000648:ultrastructure*; D008958:Models, Molecular; D010316:Particle Size; D011487:Protein Conformation
D045342:Light-Harvesting Protein Complexes