The bacterial iron-sulfur cluster (isc) operon is an essential machine that is highly conserved from bacteria to primates and responsible for iron-sulfur cluster biogenesis. Among its components are the genes for the desulfurase IscS that provides sulfur for cluster formation, and a specialized ferredoxin (Fdx) whose role is still unknown. Preliminary evidence suggests that IscS and Fdx interact but nothing is known about the binding site and the role of the interaction. Here, we have characterized the interaction using a combination of biophysical tools and mutagenesis. By modeling the Fdx·IscS complex based on experimental restraints we show that Fdx competes for the binding site of CyaY, the bacterial ortholog of frataxin and sits in a cavity close to the enzyme active site. By in vivo mutagenesis in bacteria we prove the importance of the surface of interaction for cluster formation. Our data provide the first structural insights into the role of Fdx in cluster assembly.

Ferredoxin competes with bacterial frataxin in binding to the desulfurase IscS

Salvatore Adinolfi;
2013-01-01

Abstract

The bacterial iron-sulfur cluster (isc) operon is an essential machine that is highly conserved from bacteria to primates and responsible for iron-sulfur cluster biogenesis. Among its components are the genes for the desulfurase IscS that provides sulfur for cluster formation, and a specialized ferredoxin (Fdx) whose role is still unknown. Preliminary evidence suggests that IscS and Fdx interact but nothing is known about the binding site and the role of the interaction. Here, we have characterized the interaction using a combination of biophysical tools and mutagenesis. By modeling the Fdx·IscS complex based on experimental restraints we show that Fdx competes for the binding site of CyaY, the bacterial ortholog of frataxin and sits in a cavity close to the enzyme active site. By in vivo mutagenesis in bacteria we prove the importance of the surface of interaction for cluster formation. Our data provide the first structural insights into the role of Fdx in cluster assembly.
2013
288
34
24777
24787
http://www.jbc.org/content/288/34/24777.full.pdf+html
Biophysics; Computer Modeling; Iron Metabolism; Iron-Sulfur Protein; Nuclear Magnetic Resonance; Protein Structure; Carbon-Sulfur Lyases; Escherichia coli; Escherichia coli Proteins; Ferredoxins; Iron-Binding Proteins; Protein Structure, Quaternary; Models, Molecular; Biochemistry; Molecular Biology; Cell Biology
Robert Yan, Petr V Konarev, Clara Iannuzzi, Salvatore Adinolfi, Béatrice Roche, Geoff Kelly, Léa Simon, Stephen R Martin, Béatrice Py, Frédéric Barras, Dmitri I Svergun, Annalisa Pastore
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1638579
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