Structural analysis of photosynthetic membranes by cryo-electron tomography of intact Rhodopseudomonas viridis cells

Architecture of Thylakoid Membrane Networks

“…In addition, EMT has revolutionized our understanding of the architecture and connectivity of complex membrane systems, such as mitochondria (Frey and Mannella, 2000;Nicastro et al, 2000;Mannella et al, 2001), the endoplasmic reticulum (Puhka et al, 2007), the Golgi apparatus (Marsh et al, 2001;Mironov et al, 2001;Mogelsvang et al, 2003), the photosynthetic networks of cyanobacteria (van de Meene et al, 2006;Nevo et al, 2007;Ting et al, 2007), and higher-plant chloroplasts (Shimoni et al, 2005;Austin et al, 2006). Indeed, the vision of obtaining highly resolved 3D information of whole cells (Konorty et al, 2008;Noske et al, 2008) or even tissues (Segui-Simarro et al, 2004;Hsieh et al, 2006), ultimately locating specific molecular complexes within the cell (sometimes referred to as 'visual proteomics' (Baumeister, 2002) ) seems to be within reach.…”

Cell Biology of Prokaryotic Organelles

“…In many organisms, including R. viridis, chromatophores are produced only under photosynthetic growth conditions. The CET imaging of R. viridis at early time points after switch to photosynthetic growth reveals the presence of small vesicular structures adjacent to the cell membrane (Konorty et al 2008). Presumably these early compartments eventually mature into the membrane stacks seen in cells grown under continuous photosynthetic conditions.…”

“…In contrast, in the Rhodobactericiae species these structures are spherical invaginations of the inner membrane where multiple bubbles are connected to one another. These early ultrastructural studies have recently been augmented with the CET imaging of Rhodopseudomonas viridis, an organism that forms membranes that are similar in morphology to those observed in R. palustris (Konorty et al 2008) (Fig. 2B).…”

“…The near-native state preserved by cryofixation reveals much of the same features observed in traditional electron microscopic imaging of the same organism. Membranes are folded in an accordion-like structure and they are invaginations of the inner membrane with a distinct 128 nm wide opening to the periplasmic space (Konorty et al 2008). In many organisms, including R. viridis, chromatophores are produced only under photosynthetic growth conditions.…”

Exploring photosynthesis by electron tomography

“…The photosynthetic apparatus of the purple bacterium Rhodopseudomonas viridis was investigated by electron tomography (Konorty et al 2008). This organism features stacked photosynthetic membranes (Fig.…”