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Biochim Biophys Acta. 2014 Oct;1837(10):1635-42. doi: 10.1016/j.bbabio.2014.06.002. Epub 2014 Jun 17.

The ultrastructure of Chlorobaculum tepidum revealed by cryo-electron tomography.

Author information

1
Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, 4058 Basel, Switzerland; Focal Area Infection Biology, Biozentrum, University of Basel, 4058 Basel, Switzerland.
2
Division of Biochemistry, Department of Chemistry, University of Crete, 71003 Voutes, Heraklion, Greece.
3
Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, 4058 Basel, Switzerland.
4
Division of Biochemistry, Department of Chemistry, University of Crete, 71003 Voutes, Heraklion, Greece. Electronic address: tsiotis@chemistry.uoc.gr.

Abstract

Chlorobaculum (Cba) tepidum is a green sulfur bacterium that oxidizes sulfide, elemental sulfur, and thiosulfate for photosynthetic growth. As other anoxygenic green photosynthetic bacteria, Cba tepidum synthesizes bacteriochlorophylls for the assembly of a large light-harvesting antenna structure, the chlorosome. Chlorosomes are sac-like structures that are connected to the reaction centers in the cytoplasmic membrane through the BChl α-containing Fenna-Matthews-Olson protein. Most components of the photosynthetic machinery are known on a biophysical level, however, the structural integration of light harvesting with charge separation is still not fully understood. Despite over two decades of research, gaps in our understanding of cellular architecture exist. Here we present an in-depth analysis of the cellular architecture of the thermophilic photosynthetic green sulfur bacterium of Cba tepidum by cryo-electron tomography. We examined whole hydrated cells grown under different electron donor conditions. Our results reveal the distribution of chlorosomes in 3D in an unperturbed cell, connecting elements between chlorosomes and the cytoplasmic membrane and the distribution of reaction centers in the cytoplasmic membrane.

KEYWORDS:

Chlorosome; Cryo-electron tomography; Electron microscopy; Green sulfur bacteria

PMID:
24950126
DOI:
10.1016/j.bbabio.2014.06.002
[Indexed for MEDLINE]
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