Molecular architecture of photosynthetic membranes in Rhodobacter sphaeroides : the role of PufX

Siebert, C. A. and Qian, P. and Fotiadis, D. and Engel, A. and Hunter, C. N. and Bullough, P. A.. (2004) Molecular architecture of photosynthetic membranes in Rhodobacter sphaeroides : the role of PufX. The EMBO journal, Vol. 23, H. 4. pp. 690-700.

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Official URL: http://edoc.unibas.ch/dok/A5262412

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The effects of the PufX polypeptide on membrane architecture were investigated by comparing the composition and structures of photosynthetic membranes from PufX(+) and PufX(-) strains of Rhodobacter sphaeroides. We show that this single polypeptide profoundly affects membrane morphology, leading to highly elongated cells containing extended tubular membranes. Purified tubular membranes contain helical arrays composed solely of dimeric RC-LH1-PufX (RC, reaction centre; LH, light harvesting) complexes with apparently open LH1 rings. PufX(-) cells contain crystalline membranes with a pseudo-hexagonal packing of monomeric core complexes. Analysis of purified complexes by electron microscopy and atomic force microscopy shows that LH1 and PufX form a continuous ring of protein around each RC. A model of the tubular membrane is presented with PufX located adjacent to the stained region created by a vacant LH1beta. This arrangement, coupled with a flexible ring, would give the RC Q(B) site transient access to the interstices in the lattice, which might be of functional importance. We discuss the implications of our data for the export of quinol from the RC, for eventual reduction of the cytochrome bc(1) complex.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Engel)
UniBasel Contributors:Engel, Andreas H
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Nature Publishing Group
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:22 Mar 2012 14:21
Deposited On:22 Mar 2012 13:23

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