TY  - JOUR
A1  - Kyritsis, Panayotis
A1  - Hatzfeld, Oliver M.
A1  - Link, Thomas Andreas
A1  - Moulis, Jean-Marc
T1  - The two [4Fe-4S] clusters in Chromatium vinosum ferredoxin have largely different reduction potentials. Structural origin and functional consequences
T2  - Journal of biological chemistry
N2  - The 2[4Fe-4S] ferredoxin from Chromatium vinosum arises as one prominent member of a recently defined family of proteins found in very diverse bacteria. The potentiometric circular dichroism titrations of the protein and of several molecular variants generated by site-directed mutagenesis have established that the reduction potentials of the two clusters differ widely by almost 200 mV. This large difference has been confirmed by electrochemical methods, and each redox transition has been assigned to one of the clusters. The unusually low potential center is surprisingly the one that displays a conventional CX1X2CX3X4C (Xn, variable amino acid) binding motif and a structural environment similar to that of clusters having less negative potentials. A comparison with other ferredoxins has highlighted factors contributing to the reduction potential of [4Fe-4S] clusters in proteins. (i) The loop between the coordinating cysteines 40 and 49 and the C terminus alpha-helix of C. vinosum ferredoxin cause a negative, but relatively moderate, shift of approximately 60 mV for the nearby cluster. (ii) Very negative potentials, below -600 mV, correlate with the presence of a bulky side chain in position X4 of the coordinating triad of cysteines. These findings set the framework in which previous observations on ferredoxins can be better understood. They also shed light onto the possible occurrence and properties of very low potential [4Fe-4S] clusters in less well characterized proteins.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/75878
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-758785
SN  - 0021-9258
VL  - 273.1998
IS  - 25
SP  - 15404
EP  - 15411
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -