title: Ferredoxin competes with bacterial frataxin in binding to the desulfurase IscS.
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.
authors.affiliation: MRC National Institute for Medical Research, The Ridgeway, London NW7 1AA, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Yan
authors.forename: Petr V
authors.initials: PV
authors.lastname: Konarev
authors.forename: Clara
authors.initials: C
authors.lastname: Iannuzzi
authors.forename: Salvatore
authors.initials: S
authors.lastname: Adinolfi
authors.forename: Béatrice
authors.initials: B
authors.lastname: Roche
authors.forename: Geoff
authors.initials: G
authors.lastname: Kelly
authors.forename: Léa
authors.initials: L
authors.lastname: Simon
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Martin
authors.forename: Béatrice
authors.initials: B
authors.lastname: Py
authors.forename: Frédéric
authors.initials: F
authors.lastname: Barras
authors.forename: Dmitri I
authors.initials: DI
authors.lastname: Svergun
authors.forename: Annalisa
authors.initials: A
authors.lastname: Pastore
mesh_terms: D013437:Carbon-Sulfur Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005288:Ferredoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D033862:Iron-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D020836:Protein Structure, Quaternary; D000096923:Frataxin
chemical_list: D013437:Carbon-Sulfur Lyases; D029968:Escherichia coli Proteins; D005288:Ferredoxins; D033862:Iron-Binding Proteins; D000096923:Frataxin; C120906:CyaY protein, E coli; C080546:cysteine desulfurase
keywords: Biophysics; Computer Modeling; Iron Metabolism; Iron-Sulfur Protein; Nuclear Magnetic Resonance; Protein Structure