The SUF iron-sulfur cluster biosynthetic machinery: sulfur transfer from the SUFS-SUFE complex to SUFA.
Iron-sulfur cluster biosynthesis depends on protein machineries, such as the ISC and SUF systems. The reaction is proposed to imply binding of sulfur and iron atoms and assembly of the cluster within a scaffold protein followed by transfer of the cluster to recipient apoproteins. The SufA protein from Escherichia coli, used here as a model scaffold protein is competent for binding sulfur atoms provided by the SufS-SufE cysteine desulfurase system covalently as shown by mass spectrometry. Investigation of site-directed mutants and peptide mapping experiments performed on digested sulfurated SufA demonstrate that binding exclusively occurs at the three conserved cysteines (cys50, cys114, cys116). In contrast, it binds iron only weakly (K(a)=5 x 10(5)M(-1)) and not specifically to the conserved cysteines as shown by Mössbauer spectroscopy. [Fe-S] clusters, characterized by Mössbauer spectroscopy, can be assembled during reaction of sulfurated SufA with ferrous iron in the presence of a source of electrons.
Sendra
Maïté
M
Laboratoire de Chimie et Biologie des Métaux, iRTSV/LCBM, UMR 5249, CEA-Grenoble, 17 Avenue des Martyrs, 38054 Grenoble Cedex 09, France.
Ollagnier de Choudens
Sandrine
S
Lascoux
David
D
Sanakis
Yiannis
Y
Fontecave
Marc
M
D001692:Biological Transport; D013437:Carbon-Sulfur Lyases / Q000737:chemistry* / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D008190:Lyases / Q000737:chemistry* / Q000378:metabolism; D013058:Mass Spectrometry; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D010455:Peptides / Q000737:chemistry; D025941:Protein Interaction Mapping; D013455:Sulfur / Q000378:metabolism*
D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D010455:Peptides; C499169:SufA protein, E coli; D013455:Sulfur; D007501:Iron; D008190:Lyases; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase; D003545:Cysteine