Role of conserved cysteines in mediating sulfur transfer from IscS to IscU.
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.
Smith
Archer D
AD
Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA.
Frazzon
Jeverson
J
Dean
Dennis R
DR
Johnson
Michael K
MK
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*
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