The peripheral light-harvesting complexes from purple sulfur bacteria have different ‘ring’ sizes

Kereïche, Sami; Bourinet, Laurent; Keegstra, Wilko; Arteni, Ana A.; Verbavatz, Jean-Marc; Boekema, Egbert J.; Robert, Bruno; Gall, Andrew

doi:10.1016/j.febslet.2008.09.050

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Volume 582, Issue 25 , Pages 3650-3656, 29 October 2008

The peripheral light-harvesting complexes from purple sulfur bacteria have different ‘ring’ sizes

Edited by Richard Cogdell

Sami Kereïche
- Department of Biophysical Chemistry, Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
Laurent Bourinet
- Commissariat à l’Energie Atomique, Institut de Biologie et Technologie de Saclay, et Centre National de la Recherche Scientifique, Gif sur Yvette 91191 cedex, France
Wilko Keegstra
- Department of Biophysical Chemistry, Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
Ana A. Arteni
- Department of Biophysical Chemistry, Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
Jean-Marc Verbavatz
- Commissariat à l’Energie Atomique, Institut de Biologie et Technologie de Saclay, et Centre National de la Recherche Scientifique, Gif sur Yvette 91191 cedex, France
Egbert J. Boekema
- Department of Biophysical Chemistry, Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
Bruno Robert
- Commissariat à l’Energie Atomique, Institut de Biologie et Technologie de Saclay, et Centre National de la Recherche Scientifique, Gif sur Yvette 91191 cedex, France
Andrew Gall
- Commissariat à l’Energie Atomique, Institut de Biologie et Technologie de Saclay, et Centre National de la Recherche Scientifique, Gif sur Yvette 91191 cedex, France
- Corresponding author. Fax: +33 16908717.

Received 3 September 2008; received in revised form 24 September 2008; accepted 25 September 2008. published online 06 October 2008.

Abstract

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 α and β. These apoprotein dimers are known to associate into closed circular arrays of 8, 9 and 16 α/β-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 α/β-mer. This shows that LH proteins are able to form membrane rings of continuously increasing diameter from 68 to 115Å. 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.