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Crystal structure of Bacillus thermoproteolyticus Ferredoxin Variants Containing Unexpected [3Fe-4S] Cluster that is linked to Coenzyme A at 1.6 A ResolutionCrystal structure of Bacillus thermoproteolyticus Ferredoxin Variants Containing Unexpected [3Fe-4S] Cluster that is linked to Coenzyme A at 1.6 A Resolution
Structural highlights
FunctionFER_BACTH Ferredoxins are iron-sulfur proteins that transfer electrons in a wide variety of metabolic reactions. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedDuring the purification of recombinant Bacillus thermoproteolyticus ferredoxin (BtFd) from Escherichia coli, we have noted that some Fe-S proteins were produced in relatively small amounts compared to the originally identified BtFd carrying a [4Fe-4S] cluster. These variants could be purified into three Fe-S protein components (designated as V-I, V-II, and V-III) by standard chromatography procedures. UV-vis and EPR spectroscopic analyses indicated that each of these variants accommodates a [3Fe-4S] cluster. From mass spectrometric and protein sequence analyses together with native and SDS gel electrophoresis, we established that V-I and V-II contain the polypeptide of BtFd associated with acyl carrier protein (ACP) and with coenzyme A (CoA), respectively, and that V-III is a BtFd dimer linked by a disulfide bond. The crystal structure of the BtFd-CoA complex (V-II) determined at 1.6 A resolution revealed that each of the four complexes in the crystallographic asymmetric unit possesses a [3Fe-4S] cluster that is coordinated by Cys(11), Cys(17), and Cys(61). The polypeptide chain of each complex is superimposable onto that of the original [4Fe-4S] BtFd except for the segment containing Cys(14), the fourth ligand to the [4Fe-4S] cluster of BtFd. In the variant molecules, the side chain of Cys(14) is rotated away to the molecular surface, forming a disulfide bond with the terminal sulfhydryl group of CoA. This covalent modification may have occurred in vivo, thereby preventing the assembly of the [4Fe-4S] cluster as observed previously for Desulfovibrio gigas ferredoxin. Possibilities concerning how the variant molecules are formed in the cell are discussed. Identification of variant molecules of Bacillus thermoproteolyticus ferredoxin: crystal structure reveals bound coenzyme A and an unexpected [3Fe-4S] cluster associated with a canonical [4Fe-4S] ligand motif.,Shirakawa T, Takahashi Y, Wada K, Hirota J, Takao T, Ohmori D, Fukuyama K Biochemistry. 2005 Sep 20;44(37):12402-10. PMID:16156653[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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