Ferredoxins evolution

Ferredoxins are electron-transfer proteins that can mediate between pyruvate ferredoxin oxidoreductase and hydrogenase. It appears that during the course of the evolution, different types of ferredoxin were recruited for this purpose. In Clostridia, ferredoxins of the 2[4Fe-4S] type are used (Uyeda and Rabinowitz 1971). In T. vaginalis (Chapman et al. 1986) and T. foetus (Marczak et al. 1983), [2Fe-2S] ferredoxins are used. Their axial EPR spectra at g = 1.94,2.02 (Fig. 9.2) resemble those of the ferredoxins that are involved in P450 monooxygenase systems. Similar ferredoxins, with various functions, have been isolated from... 

Hall DO, Cammack R, Rao KK. 1971. A role for ferredoxins in the origin of life and biological evolution. Nature 233 136-8. 

CHO] Ferredoxin Hydrogenase H2 Light driven hydrogen evolution ... 

Fukuyama, K., Hase, T., Matsumoto, S., Tsukihara, T., Katsube, Y., Tanaka, N., Kakudo, M., Wada, K., and Matsubara, H. (1980). Structure of S. platensis [2Fe-2S] ferredoxin and evolution of chloroplast-type ferredoxins. Nature (London) 286, 522-524. 

Horner DS, Hirt RP, Embley TM (1999) A single eubacterial origin of eukaryotic pyruvate ferredoxin oxidoreductase genes implications for the evolution of anaerobic eukaryotes. Mol Biol Evol 16 1280-1291... 

Whereas the electron acceptors in the anaerobic organisms are the bacterial-type ferredoxins that contain [4Fe-S] clusters as the redox center, in the case of the halobacteria the electrons are transferred to [2Fe-S] ferredoxins. These ferredoxins were isolated from two different halobacteria and their amino acid sequences were determined (Hase et al., 1977, 1980) and shown to be highly homologous to the chloroplast (and cyanobacterial) ferredoxins. The implications of these perplexing findings for the question of the molecular evolution of the system is discussed in detail in Kerscher and Oesterhelt (1982). 

Otaka, E and Ooi, T. (1987) Examination of Protein Sequence Homologies IV Twenty-Seven Bacterial Ferredoxins, Journal of Molecular Evolution, 26, 257-268. 

However, in 1962, Mortenson, Valentine, and Carnahan (75) isolated a protein from C. pasteurianum which linked the anaerobic oxidation of pyruvate to the evolution of hydrogen gas. They reported the partial purification of this protein, showed its iron content, and in view of its characteristics, they suggested it be called ferredoxin. The role of fer-redoxin in the anaerobic breakdown of pyruvate is shown in Eqs. 4—7. 

Apart from hydrogen evolution, the electrons of reduced ferredoxin can take alternative routes leading to biosynthesis. In anaerobic bacteria, reduced ferredoxin can be used directly for the reduction of pyridine nucleotides (Tagawa and Arnon (99) Valentine, Brill and Wolfe (107) Fredericks and Stadtman (44)) for the reduction of hydroxyla-mine to ammonia (Valentine, Mortenson, Mower, Jackson, and Wolfe (109) for COa fixation in the reductive carboxylation of acetyl-CoA to pyruvate (Bachofen, Buchanan, and Arnon (13) Raeburn and Rabino-witz (83) Andrews and Morris (3) Stern (98)) for the reduction of sulfite to sulfide (Akagi (1)) and, in the presence of ATP, it can be used for the reduction of N2 to NH3 (Mortenson (72,73) D Eustachio and Hardy (40)). The role of ferredoxin in these reactions as well as in the oxidative degradative reactions discussed above is summarized in Fig. 10. 

Ferredoxin is believed to function as the first electron acceptor of photoactivated chlorophyll Tagawa and Arnon 99) San Pietro 85)). In net electron flow, the electrons for reducing ferredoxin originate from water, pass to chlorophyll and then to ferredoxin. The reduction of ferredoxin is coupled to the evolution of oxygen Arnon, Tsujimoto, and McSwain (8)). It is emphasized that oxygen evolution end ferredoxin reduction are closely associated and, in the presence of ADP and Pi, they... 

As pointed out previously, illuminated chloroplast fragments are convenient for reducing ferredoxin and, in the presence of the appropriate enzymes, photoreduced ferredoxin can be used in processes that may have nothing to do with green plants. For example, in the presence of bacterial hydrogenase, photoreduced ferredoxin is used for the evolution of hydrogen gas (Tagawa and Arnon (99)) and, in the presence of other bacterial enzymes, it is used for reductive carboxylation reactions (Bachofen, Buchanan, and Arnon (13) Buchanan and Evans (30)). 

In studying the evolution of iron-sulfur proteins, the requirements of the ferredoxins for specifically placed cysteines to bind the irons in the active center have been most useful. Figure 6 shows sequences of the ferredoxins from several obligate fermenting anaerobic bacteria, green... 

Benemann, J.R., Berenson, J.A., Kaplan, N.O. and Kamen, M.D. 1973. Hydrogen evolution by a chloroplalst-ferredoxin-hydrogenase system. Proc. Natl. Acad. Sci. USA 70, 2317-2320... 

For cyclic electron flow, an electron from the reduced form of ferredoxin moves back to the electron transfer chain between Photosystems I and II via the Cyt bCyclic electron flow does not involve Photosystem II, so it can be caused by far-red light absorbed only by Photosystem I — a fact that is often exploited in experimental studies. In particular, when far-red light absorbed by Photosystem I is used, cyclic electron flow can occur but noncyclic does not, so no NADPH is formed and no O2 is evolved (cyclic electron flow can lead to the formation of ATP, as is indicated in Chapter 6, Section 6.3D). When light absorbed by Photosystem II is added to cells exposed to far-red illumination, both CO2 fixation and O2 evolution can proceed, and photosynthetic enhancement is achieved. Treatment of chloroplasts or plant cells with the 02-evolution inhibitor DCMU [3-(3,4-dichlorophenyl)-l, 1-dimethyl urea], which displaces QB from its binding site for electron transfer, also leads to only cyclic electron flow DCMU therefore has many applications in the laboratory and is also an effective herbicide because it markedly inhibits photosynthesis. Cyclic electron flow may be more common in stromal lamellae because they have predominantly Photosystem I activity. 

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