Heliobacterial Rieske/cytb complex

Baymann, Frauke; Nitschke, Wolfgang

doi:10.1007/s11120-009-9524-1

Cited by 18 publications

(17 citation statements)

References 68 publications

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“…Unfortunately, as discussed in Baymann and Nitschke (2010), the lack of a functional isolate hampers more indepth comparisons of the heliobacterial complex with its better studied homologs. Nevertheless, the results obtained on Heliobacteria so far (summarised in Baymann and Nitschke 2010) are helpful to better define the evolutionary appearance of specific marker traits and functional particularities within this enzyme family.…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless, the results obtained on Heliobacteria so far (summarised in Baymann and Nitschke 2010) are helpful to better define the evolutionary appearance of specific marker traits and functional particularities within this enzyme family.…”

Section: Discussionmentioning

confidence: 99%

“…As discussed in (Baymann and Nitschke 2010), the physiological role of heme c i is presently not yet understood and several conflicting hypotheses are in the literature (Stroebel et al 2003;Kurisu et al 2003;Alric et al 2005;Twigg et al 2009). It is inevitable, though, that the insertion of this additional cofactor must have dramatically altered the mode of functioning of the Q i -site.…”

Section: Turnover Of the Q I -Sitementioning

confidence: 99%

“…It is inevitable, though, that the insertion of this additional cofactor must have dramatically altered the mode of functioning of the Q i -site. Optical and EPR spectroscopy indicated profound differences in Q i turnover between b 6 f complexes from Cyanobacteria/chloroplasts (containing heme c i ) and the bulk of bc 1 -type enzymes (for a discussion see Baymann and Nitschke 2010). In vivo time-resolved optical spectroscopy on Heliobacteria (Kramer et al 1997) demonstrated that the Q i site turnover resembles in many aspects that of b 6 f complexes, an observation which now finds a rationalisation in the presence of heme c i in both systems (Ducluzeau et al 2008).…”

Section: Turnover Of the Q I -Sitementioning

confidence: 99%

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The “green” phylogenetic clade of Rieske/cytb complexes

et al. 2010

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More than a decade ago, Heliobacteria were recognised to contain a Rieske/cytb complex in which the cytochrome b subunit is split into two separate proteins, a peculiar feature characteristic of the cyanobacterial and plastidic b (6) f complex. The common presence of RCI-type reaction centres further emphasise possible evolutionary links between Heliobacteria, Chlorobiaceae and Cyanobacteria. In this contribution, we further explore the evolutionary relationships among these three phototrophic lineages by both molecular phylogeny and consideration of phylogenetic marker traits of the superfamily of Rieske/cytb complexes. The combination of these two methods suggests the existence of a "green" clade involving many non-phototrophs in addition to the mentioned RCI-type photosynthetic organisms. Structural and functional idiosyncrasies are (re-)interpreted in the framework of evolutionary biology and more specifically evolutionary bioenergetics.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Turnover Of the Q I -Sitementioning

confidence: 99%

Section: Turnover Of the Q I -Sitementioning

confidence: 99%

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The “green” phylogenetic clade of Rieske/cytb complexes

et al. 2010

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“…1B), because CO 2 is produced through the OTCA cycle. Table 2 shows that over 50% aspartate and 60% glutamate were labeled in the ␤-carboxyl group with [1][2][3][4][5][6][7][8][9][10][11][12][13] C]pyruvate as the carbon source, implying that citrate formation is possibly catalyzed by (Re)-citrate synthase ((Re)-CS) (Fig. 3).…”

Section: Carbon Metabolism In H Modesticaldummentioning

confidence: 99%

Carbon Flow of Heliobacteria Is Related More to Clostridia than to the Green Sulfur Bacteria

Tang

Feng

Zhuang

et al. 2010

Journal of Biological Chemistry

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The recently discovered heliobacteria are the only Gram-positive photosynthetic bacteria that have been cultured. One of the unique features of heliobacteria is that they have properties of both the photosynthetic green sulfur bacteria (containing the type I reaction center) and Clostridia (forming heat-resistant endospores). Most of the previous studies of heliobacteria, which are strict anaerobes and have the simplest known photosynthetic apparatus, have focused on energy and electron transfer processes. It has been assumed that like green sulfur bacteria, the major carbon flow in heliobacteria is through the (incomplete) reductive (reverse) tricarboxylic acid cycle, whereas the lack of CO 2 -enhanced growth has not been understood. Here, we report studies to fill the knowledge gap of heliobacterial carbon metabolism. We confirm that the CO 2 -anaplerotic pathway is active during phototrophic growth and that isoleucine is mainly synthesized from the citramalate pathway. Furthermore, to our surprise, our results suggest that the oxidative (forward) TCA cycle is operative and more active than the previously reported reductive (reverse) tricarboxylic acid cycle. Both isotopomer analysis and activity assays suggest that citrate is produced by a putative (Re)-citrate synthase and then enters the oxidative (forward) TCA cycle. Moreover, in contrast to (Si)-citrate synthase, (Re)-citrate synthase produces a different isomer of 2-fluorocitrate that is not expected to inhibit the activity of aconitase.Heliobacteria are a relatively newly discovered group of anaerobic photosynthetic bacteria. All of the cultured heliobacteria require organic carbon for anoxygenic growth, and several of the species can fix nitrogen (1, 2). Heliobacteria are the only cultured Gram-positive photosynthetic bacteria and are phylogenetically related to the bacterial phylum Firmicutes, such as the aerobic Bacillus and anaerobic Clostridia (1). Among 10 cultured heliobacteria (2), Heliobacterium modesticaldum is the only one that can grow at temperatures of Ͼ50°C. Madigan and co-workers (1, 3) reported that pyruvate, lactate, acetate (ϩHCO 3 Ϫ ), or yeast extract can support the phototrophic growth of H. modesticaldum, and our recent studies demonstrated that D-sugars can also support the growth of H. modesticaldum (4).An unusual feature of heliobacteria is that they have properties of both green sulfur bacteria (containing the type I reaction center) and Clostridia (forming heat-resistant endospores) (1). Heliobacteria have the simplest photosynthetic apparatus among the photosynthetic organisms (5), and most of the research on them has been focused on understanding the photosynthetic machinery and energy transfer processes (1, 6 -8).In contrast, our knowledge of phototrophic carbon metabolism by heliobacteria is still poorly developed.Only two reported studies have experimentally probed the carbon metabolism of heliobacteria; one is our recent study with H. modesticaldum (4), and the other is the 1994 report by Kelly and co-workers (9) on Hel...

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Cytochrome b 6 f Complex at the Heart of Energy Transduction and Redox Signaling

Kallas

2011

Photosynthesis

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Heliobacterial Rieske/cytb complex

Cited by 18 publications

References 68 publications

The “green” phylogenetic clade of Rieske/cytb complexes

The “green” phylogenetic clade of Rieske/cytb complexes

Carbon Flow of Heliobacteria Is Related More to Clostridia than to the Green Sulfur Bacteria

Cytochrome b 6 f Complex at the Heart of Energy Transduction and Redox Signaling

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