Structure and functions of a very small tetraheme protein -Molecular mechanism of bioremediation-

many Shewanella species of many Shewanella species is their ability to reduce insolublemetal oxides, including ironmanganese. S. putrefaciens strain MR1 was specifically isolated as a metal oxide (iron andmanganese reducing organismand shown to couple the reduction of metal oxides to the oxidation of organic carbon the ability ofShewanella species to grow with a variety of different electron acceptors having redox potentialsfrom +0.8 V (oxygen) to about 0 (elemental sulfur) implies that this bacterium is able to just togrowth conditions through changes in the activity and/or the composition of the electron transportchain. Cytochromes are abundant in Shewanella and have been implicated in the reduction of metaloxides. The redox behavior of a tetraheme protein，cytochrome c - D23 - D2 was investigated in this work. The macroscopic and microscopic redoxpotentials were determined at pH 9. Although they are low in comparison with其他cytochromes，they are higher than the redox potentials of cytochrome c D23 D2 from Desulfovibrio vulgarisMiyazaki F (DvMF). DvMF cytochrome c - D23 - D2 gene was successfully expressed in a facultativeaerobe, Shewanella putrefaciens MR-I, under anaerobic, microaerobic，aerobic conditions with good yields. A derivative of the broad-host-range plasmid pRK415containing the cytochrome c - D23 - D2，genes from DvMF was used for transformation of S. putrefaciens MR-1resulting in the production of holocytochrome c - D23 - D2 that was indistinguishable from thatproduced by D. vulgaris Miyazaki

The most remarkable characteristic of many Shewanella species is their ability to reduce insoluble metal oxides, including iron, and manganese. S. putrefaciens strain MR1 was specifically isolated as a metal oxide (iron and manganese) reducing organism, and shown to couple the reduction of metal oxides to the oxidation of organic carbon. The ability of Shewanella species to grow with a variety of different electron acceptors having redox potentials from +0.8 V (oxygen) to about 0 (elemental sulfur) implies that this bacterium is able to adjust to growth conditions through changes in the activity and/or the composition of the electron transport chain. Cytochromes are abundant in Shewanella and have been implicated in the reduction of metal oxides. The redox behavior of a tetraheme protein, cytochrome cィイD23ィエD2 was investigated in this work. The macroscopic and microscopic redox potentials were determined at pH 9. Although they are low in comparison with other cytochromes, they are higher than the redox potentials of cytochrome cィイD23ィエD2 from Desulfovibrio vulgaris Miyazaki F (DvMF). DvMF cytochrome cィイD23ィエD2 gene was successfully expressed in a facultative aerobe, Shewanella putrefaciens MR-I, under anaerobic, microaerobic, and aerobic conditions with good yields. A derivative of the broad-host-range plasmid pRK415 containing the cytochrome cィイD23ィエD2, genes from DvMF was used for transformation of S. putrefaciens MR-1, resulting in the production of holocytochrome cィイD23ィエD2 that was indistinguishable from that produced by D. vulgaris Miyazaki F.