TY - JOUR
T1 - Evidence for the existence of [2Fe-2S] as well as [4Fe-4S] clusters among FA, FB and FX. Implications for the structure of the Photosystem I reaction center
AU - Golbeck, John H.
AU - McDermott, Ann E.
AU - Jones, Wayne K.
AU - Kurtz, D. M.
N1 - Funding Information:
steines to hold two iron-sulfur clusters; a dimeric arrangement of one PS I-A1 and one PS I-A2 peptide would not. An interaction of two iron-sulfur clusters has been postulated to explain some of the unusual properties exhibited by F x \[27\]. For example, the low gay value of 1.91, the extremely broad ESR resonances, and the low redox potential are highly unusual for a \[4Fe-4S\]c luster \[see Ref. 25\]. Moreover, the ESR microwave power saturation characteristics have indicated that F x cannot be a typical \[2Fe-2S\]o r \[4Fe-4S\]c luster \[26\].T he model of F x suggested here, while speculative, provides for a novel structure through the interaction of two iron-sulfur clusters while preserving the fundamental stoichiometry of the Photosystem I components. This research was supported by grants from the National Science Foundation to JHG (DMB-8517391) and DMK (DMB-8216447).
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 1987/3/25
Y1 - 1987/3/25
N2 - Core extrusion of the bound iron-sulfur centers from spinach Photosystem I showed the presence of [2Fe-2S] clusters as well as [4Fe-4S] clusters among FA, FB and FX. Extrusion of the iron-sulfur ensemble was not quantitative; however, the presence of [2Fe-2S] clusters correlated with higher concentration of unfolding solvent. Since FX is highly resistant to denaturation, and since FA and FB are known to contain [4Fe-4S] clusters, the [2Fe-2S] clusters are assigned to FX. The presence of [2Fe-2S] clusters in Photosystem I has significance in the structure and organization of FX on the reaction center. Since four cysteinyl ligands are assumed to hold an iron-sulfur cluster, a Photosystem I subunit may consist of two approx. 64-kDa proteins bridged by a single [2Fe-2S] cluster. The complete reaction center would consist of two subunits positioned so that two [2Fe-2S] clusters are in magnetic interaction, thereby constituting FX.
AB - Core extrusion of the bound iron-sulfur centers from spinach Photosystem I showed the presence of [2Fe-2S] clusters as well as [4Fe-4S] clusters among FA, FB and FX. Extrusion of the iron-sulfur ensemble was not quantitative; however, the presence of [2Fe-2S] clusters correlated with higher concentration of unfolding solvent. Since FX is highly resistant to denaturation, and since FA and FB are known to contain [4Fe-4S] clusters, the [2Fe-2S] clusters are assigned to FX. The presence of [2Fe-2S] clusters in Photosystem I has significance in the structure and organization of FX on the reaction center. Since four cysteinyl ligands are assumed to hold an iron-sulfur cluster, a Photosystem I subunit may consist of two approx. 64-kDa proteins bridged by a single [2Fe-2S] cluster. The complete reaction center would consist of two subunits positioned so that two [2Fe-2S] clusters are in magnetic interaction, thereby constituting FX.
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U2 - 10.1016/0005-2728(87)90087-9
DO - 10.1016/0005-2728(87)90087-9
M3 - Article
AN - SCOPUS:45949116222
VL - 891
SP - 94
EP - 98
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
SN - 0005-2728
IS - 1
ER -