title: Role of conserved cysteines in mediating sulfur transfer from IscS to IscU.
abstract: The role of the three conserved cysteine residues on Azotobacter vinelandii IscU in accepting sulfane sulfur and forming a covalent complex with IscS has been evaluated using electrospray-ionization mass spectrometry studies of variants involving individual cysteine-to-alanine substitutions. The results reveal that IscS can transfer sulfur to each of the three alanine-substituted forms of IscU to yield persulfide or polysulfide species, and formation of a heterodisulfide covalent complex between IscS and Cys(37) on IscU. It is concluded that S transfer from IscS to IscU does not involve a specific cysteine on IscU or the formation of an IscS-IscU heterodisulfide complex.
authors.affiliation: Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA.
authors.forename: Archer D
authors.initials: AD
authors.lastname: Smith
authors.forename: Jeverson
authors.initials: J
authors.lastname: Frazzon
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Dean
authors.forename: Michael K
authors.initials: MK
authors.lastname: Johnson
mesh_terms: D016948:Azotobacter vinelandii / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013455:Sulfur / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; C411665:IscU protein, E coli; D013455:Sulfur; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase; D003545:Cysteine