Green sulfur photosynthetic bacterium

The reductive TCA cycle uses CO2 for producing acetyl-CoA [28, 29]. Two CO2 units are converted in each cycle into acetyl-CoA using one ATP and four NAD(P) H units. The full cycle was first reported to be found in a green sulfur photosynthetic bacterium Chlorobium limicola) and was later also found to operate in Aquificales, Archeal Crenarcheota, and various types of proteobacteria. 

Fig. 5.2. The photosynthetic membrane of a green sulfur bacterium. The light-activated bacte-riochlorophyll molecule sends an electron through the electron-transport chain (as in respiration) creating a proton gradient and ATP synthesis. The electron eventually returns to the bacteri-ochlorophyll (cyclic photophosphorylation). If electrons are needed for C02 reduction (via reduction of NADP+), an external electron donor is required (sulfide that is oxidised to elemental sulfur). Note the use of Mg and Fe.

Figure 23-28 (A) Model of a light-harvesting chlorosome from green photosynthetic sulfur bacteria such as Chlorobium tepidum and species of Prosthecochloris. The chlorosome is attached to the cytoplasmic membrane via a baseplate, which contains the additional antenna bacteriochlorophylls (795 BChl a) and is adjacent to the trimeric BChl protein shown in (B) and near the reaction center. After Li et al.302 and Remigy et a/.304 (B) Alpha carbon diagram of the polypeptide backbone and seven bound BChl a molecules in one subunit of the trimeric protein from the green photosynthetic bacterium Prosthecochloris. For clarity, the magnesium atoms, the chlorophyll ring substituents, and the phytyl chains, except for the first bond, are omitted. The direction of view is from the three-fold axis, which is horizontal, toward the exterior of the molecule. From Fenna and Matthews.305 See also Li et al.302...

Fig. 6. Absorbance changes induced by 33-ps, 850-nm laser pulses in Complex 1 obtained from membranes of the green sulfur bacterium Pc. aestuarff. (A) Membrane with "closed RCs (sample containing FeCy and under background Illumination) (B) membrane with open RCs (sample containing Asc and PMS). Solid-line traces represent absorbance changes observed at the time the excitation flash was applied, and the dotted-line traces are for changes observed at 350 ps after the flash. Figure source Shuvalov, Amesz and Duysens (1986) Picosecond spectroscopy of isolated membranes of the photosynthetic green sulfur bacterium Prosthecochloris aestuarii upon selective excitation of the primary electron donor. Biochim Biophys Acta. 851 2, 3.

U Feller, W Nitschke and FI Michel (1992) Characterization of an improved reaction center preparation from the photosynthetic green sulfur bacterium Chlorobium containing the FeS centers F and F and a bound cytochrome subunit. Biochemistry 31 2608-2614... 

Fig. 17.15-C(s-carotenoids identified so far in the RCs of various photosynthetic organisms (a) neurosporene, (b) spheroidene and (c) spirilloxanthin in the quinone-type RC of puiple non-sulfur bacteria, Rb. sphaeroides QIC, 2.4.1 and Rs. rubrum SI (d) y-carotene and (e) chlorobactene in the iron sulfiir-type RC of green sulfur bacterium, Cb. tepidum-, and (f) Carotene in the quinone-type PS II RC of spinach chioropiasts as well as in the iron sulfur-type PS I RC of a cyanobacterium. Sc. vulcanus, and spinach chioropiasts.

FI Vasmel, T Swarthoff, FIJM Kramer and J Amesz (1983) Isolation and properties of a pigment protein complex associated with the reaction center of the green photosynthetic sulfur bacterium Prosthecochloris aestuarii. Biochim Biophys Acta 725 361-367... 

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