Chlorobium thiosulfatophilum

The RCC proceeds formally in exactly the opposite direction, from the C4 molecule to the C6 molecule via uptake of C02, but without the help of highly specialized enzymes. However, it is not a hypothetical archaic phenomenon, but has been observed in cells which exist today, for example in the photosynthetic bacterium Chlorobium thiosulfatophilum (Evans et al., 1966). 

Cork [283], Sublette [284], and others have identified a number of chemolithotrophic bacteria which oxidize elemental sulfur and use reduced or partially reduced sulfur compounds as an energy source, in the presence of various carbon sources (such as carbon dioxide or bicarbonate) and reduced nitrogen (e.g., ammonium ion). In the case of Cork et al. s work, the anaerobic photosynthetic bacterium Chlorobium thiosulfatophilum is used to convert sulfides to sulfate. The economics of this process was not favorable due to the requirement of light for the growth of the bacterium. 

Meyer, T. E., Bartsch, R. G., Caffrey, M. S., and Cusanovich, M. A., 1991a, Redox potentials of flavocytochrome c from the phototrophic bacteria Chromatium vinosum and Chlorobium thiosulfatophilum. Arch. Biochem. Biophys. 287 12811134. 

C. Green sulfur (Chlorobacteriaceae) Chlorobium thiosulfatophilum (NCIB 8346) ... 

Buchanan, B. B., Matsubara, H., Evans, M. C. W., "Ferredoxin from the Photosynthetic Bacterium, Chlorobium thiosulfatophilum—Link to Ferredoxins from Nonphotosyndietic Bacteria, Biochim, Biophys, Acta (1969) 189, 46. 

C555 Chlorobium thiosulfatophilum Prostheochloris aestuarii Photosynthesis... 

Chlorobium thiosulfatophilum uses hydrogen sulfide as a source of electrons for photosynthesis. Write the basic equation for H2S-based photosynthesis. Given the fact that the standard reduction potential for S -l- 2 —> H2S is -1-0.14 y does it seem likely that... 

A thiohemiacetal function is possibly contained in a related enzyme, flavocytochrome C553 from Chlorobium thiosulfatophilum (2), where in fact a flavocoenzyme can be released from the protein under condition similar to those employed for the Chromatium cytochrome C552, and has properties very similar to those of the flavin from Chromatium cytochromes C552. 

Figure 5. Anaerobic sulfide and thiosulfate oxidation by a growing culture of Chlorobium vibrioforme f. thiosulfatophilum (Reproduced with permission from Ref. 17. Copyright 1982 Springer-Verlag New York Inc.).

In Chlorobium limicola . thiosulfatophilum cytochrome c-SSl serves as electron acceptor of thiosulfate oxidation, before the electrons flow to oxidized bacteriochlorophyll via a soluble small cytochrome c-SSS and a membrane-bound cytochrome (2). The absence of cytochrome c-SSl in the non-thiosulfate-utilizing Chlorobiaceae might be one explanation why these organisms cannot use thiosulfate (4). 

Chlorobium liimcola . thiosulfatophilum (22) and ThiQgaBfia roseopersicina (461 do not contain siroheme sulfite reductases, although sulfite reductase activity was measured in the last organism. 

If phototrophic bacteria possess a dissimilatory ATP-sulfurylase, they convert APS with pyrophosphate directly to ATP and sulfate, without the help of an additional enzyme. Such an enzyme is necessary, if the organisms like Chlorobium vibrioforme f. thiosulfatophilum (Table IV) contain only the ADP-sulfurylase, because this enzyme liberates only ADP and sulfate from APS in the presence of inorganic phosphate. In this case, the organisms gain one ATP molecule from 2 molecules of ADP. This reaction is catalyzed by adenylate kinase which converts 2 ADP into 1 ATP and 1 AMP (38). 

FI Oh-oka, S Kakutani, FI Matsubara, R Malkin and S Itoh (1993) Isolation of the photoactive reaction center complex that contains three types ofFe-S centers and a cytochrome c subunit from the green sulfur bacterium Chlorobium limicola f. thiosulfatophilum strain Larsen. Plant Cell Physiol 34 93-101... 

Flavocytochromes c from Chlorobium limicola f. thiosulfatophilum and Allo-chromatium (formerly Chromatium) vinosum have been reported to catalyze the reduction of elemental sulfur with strong reducing reagents such as benzyl viologen radical (Fukumori and Yamanaka, 1979 Yamanaka and Fukumori, 1980). 

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