Roles of ATP and NADPH in Formation of the Fe-S Cluster of Spinach Ferredoxin
- 1 January 1991
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 95 (1) , 104-110
- https://doi.org/10.1104/pp.95.1.104
Abstract
Ferredoxin (Fd) in higher plants is encoded by a nuclear gene, synthesized in the cytoplasm as a larger precursor, and imported into the chloroplast, where it is proteolytically processed, and assembled with the [2Fe-2S] cluster. The final step in the biosynthetic pathway of Fd can be analyzed by a reconstitution system composed of isolated chloroplasts and [35S]cysteine, in which [35S]sulfide and iron are incorporated into Fd to build up the 35S-labeled Fe-S cluster. Although a lysed chloroplast system shows obligate requirements for ATP and NADPH, in vitro chemical reconstitution of the Fe-S cluster is generally thought to be energy-independent. The present study investigated whether ATP and NADPH in the chloroplast system of spinach (Spinacia oleracea) are involved in the supply of [35S]sulfide or iron, or in Fe-S cluster formation itself. [35S]Sulfide was liberated from [35S] cysteine in an NADPH-dependent manner, whereas ATP was not necessary for this process. This desulfhydration of [35S]cysteine occurred before the formation of the 35S-labeled Fe-S cluster, and the amount of radioactivity in [35S]sulfide was greater than that in 35S-labeled holo-Fd by a factor of more than 20. Addition of nonradioactive sulfide (Na2S) inhibited competitively formation of the 35S-labeled Fe-S cluster along with the addition of nonradioactive cysteine, indicating that some of the inorganic sulfide released from cysteine is incorporated into the Fe-S cluster of Fd. ATP hydrolysis was not involved in the production of inorganic sulfide or in the supply of iron for assembly into the Fe-S cluster. However, ATP-dependent Fe-S cluster formation was observed even in the presence of sufficient amounts of [35S]sulfide and iron. These results suggest a novel type of ATP-dependent in vivo Fe-S cluster formation that is distinct from in vitro chemical reconstitution. The implications of these results for the possible mechanisms of ATP-dependent Fe-S cluster formation are discussed.Keywords
This publication has 19 references indexed in Scilit:
- Formation of the Fe-S Cluster of Ferredoxin in Lysed Spinach ChloroplastsPlant Physiology, 1991
- Several proteins imported into chloroplasts form stable complexes with the GroEL-related chloroplast molecular chaperone.Plant Cell, 1989
- Identification of a novel nifH-like (frxC) protein in chloroplasts of the liverwort Marchantia polymorphaPlant Molecular Biology, 1989
- Molecular chaperones: proteins essential for the biogenesis of some macromolecular structuresTrends in Biochemical Sciences, 1989
- S-Phosphocysteine and phosphohistidine are intermediates in the phosphoenolpyruvate-dependent mannitol transport catalyzed by Escherichia coli EIImtlBiochemistry, 1988
- Ribulose bisphosphate carboxylase assembly: what is the role of the large subunit binding protein?Trends in Biochemical Sciences, 1988
- Stromal serine protein kinase activity in spinach chloroplastsArchives of Biochemistry and Biophysics, 1987
- Iron transport and storageEuropean Journal of Biochemistry, 1987
- Induction and activation of cysteine oxidase of rat liver II. The measurement of cysteine metabolism in vivo and the activation of in vivo activity of cysteine oxidaseBiochimica et Biophysica Acta (BBA) - General Subjects, 1973
- DISC ELECTROPHORESIS – II METHOD AND APPLICATION TO HUMAN SERUM PROTEINS*Annals of the New York Academy of Sciences, 1964