Iron-sulfur proteins Rieske-type

Although the redox potential of Rieske-type clusters is approximately 400 mV lower than that of Rieske clusters, it is 300 mV more positive than the redox potential of plant-type ferredoxins (approximately -400 mV). Multiple factors have been considered to be essential for the redox potential of iron sulfur proteins ... 

Since their discovery, Rieske proteins have been the object of numerous studies aimed at gaining insight into the molecular basis of their unique properties. These studies not only have shed light on Rieske and Rieske-type clusters, but also have contributed to the understanding of iron sulfur proteins in general. 

Figure 5 The most commonly encountered FeS centers (a) the monoiron center of rubredoxin, (b) the FeySy cluster of plant-type ferredoxins, (c) the FeySy cluster of Rieske proteins, (d) the Fe3S4 cluster of ferredoxins, and (e) the Fe4 4 cluster of ferredoxins and high potential iron-sulfur proteins (FliPiPs).

Chloroplast ferredoxin containing the [(2Fe-2S)-(S-Cys)4] cluster is one common type of iron-sulfur protein. Another [2Fe-2S]-type protein is the Rieske iron-sulfur protein, present in the Cyt >6/complex as well as the Cyt Ac, complex. The pair of iron atoms in the cluster ofthe Rieske iron-sulfur protein are bound to two cysteine and two histidine residues, in addition to two sulfur atoms. The three-dimensional structures of ferredoxins and that of the Rieske iron-sulfur protein have been determined by X-ray crystallography (see Chapters 34 and 35, respectively, for the structure ofthe chloroplast ferredoxin and the Rieske iron-sulfur protein). The sulfide ions in iron-sulfur proteins urt acid-labile this provides a simple means for detecting the iron-sulfur proteins, as the sulfide is released as H2S upon acidification. The oxidized and reduced states of iron-sulfur clusters differ by just one unit of formal charge, corresponding to and Fe. Iron-sulfurproteins are commonly characterized by optical absorption, circular-dichro-... 

The first electron from the reduced quinone are transferred to a -type cytochrome and a second electron to the Rieske iron-sulfur protein and cytochrome c, in the cytochrome-6Cj complex. These electrons are subsequently transferred to cytochrome C2 on the periplasmic side ofthe plasma membrane and finally go to reduce the oxidized primary electron donor P870 to complete the cyclic reaction. 

Pruzinska A, Tanner G, Anders I, Roca M, Hortensteiner S (2003) Chlorophyll Breakdown Pheophorbide a Oxygenase is a Rieske-type Iron-sulfur Protein, Encoded by the Accelerated Cell Death 1 Gene. Proc Natl Acad Sci USA 100 15259... 

An excellent example of the powerful combination of ENDOR with isotopic labeling studies is found in the identification of histidine ligands in the Rieske-type 2Fe-2S iron-sulfur protein of phthalate dioxygenase (PDO). As shown in Fig. 12, the X-band " N cw ENDOR spectrum of natural-abundance PDO shows a broad pattern of N resonances that by... 

There are several major types of iron-sulfur proteins, i.e. the rubredoxin (Rb), ferredoxin, Rieske protein, and the high-potential iron-protein (HiPIP). 

---