A bacterial 2[4Fe 4S] ferredoxin as redox partner of the plastidic-type ferredoxin-NADP+ reductase from Leptospira interrogans

LÓPEZ RIVERO, ARLETH S.; ROSSI, MA. AGUSTINA; CECCARELLI, EDUARDO A.; CATALANO-DUPUY, DANIELA L.

BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS

ELSEVIER SCIENCE BV

Año: 2019 vol. 1863 p. 651 - 660

0304-4165

BackgroundFerredoxins are small iron-sulfur proteins that participate as electron donors in various metabolic pathways. They are recognized substrates of ferredoxin-NADP+ reductases (FNR) in redox metabolisms in mitochondria, plastids, and bacteria. We previously found a plastidic-type FNR in Leptospira interrogans (LepFNR), a parasitic bacterium of animals and humans. Nevertheless, we did not identify plant-type ferredoxins or flavodoxins, the common partners of this kind of FNR.MethodsSequence alignment, phylogenetical analyses and structural modeling were performed for the identification of a 2[4Fe4S] ferredoxin (LepFd2) as a putative redox partner of LepFNR in L. interrogans. The gene encoding LepFd2 was cloned and the protein overexpressed and purified. The functional properties of LepFd2 and LepFNR-LepFd2 complex were analyzed by kinetic and mutagenesis studies.ResultsWe succeeded in expressing and purifying LepFd2 with its FeS cluster properly bound. We found that LepFd2 exchanges electrons with LepFNR. Moreover, a unique structural subdomain of LepFNR (loop P75-Y91), was shown to be involved in the recognition and binding of LepFd2. This structural subdomain is not found in other FNR homologs.ConclusionsWe report for the first time a redox pair in L. interrogans in which a plastidic FNR exchanges electron with a bacterial 2[4Fe4S] ferredoxin. We characterized this reaction and proposed a model for the productive LepFNR-LepFd2 complex.General significanceOur findings suggest that the interaction of LepFNR with the iron-sulfur protein would be different from the one previously described for the homolog enzymes. This knowledge would be useful for the design of specific LepFNR inhibitors.