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.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Azotobacter vinelandii / metabolism
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Carbon-Sulfur Lyases / genetics
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Carbon-Sulfur Lyases / metabolism*
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Cysteine / metabolism*
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Escherichia coli Proteins / genetics
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Escherichia coli Proteins / metabolism
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Iron-Sulfur Proteins / genetics
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Iron-Sulfur Proteins / metabolism
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Spectrometry, Mass, Electrospray Ionization
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Sulfur / metabolism*
Substances
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Bacterial Proteins
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Escherichia coli Proteins
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Iron-Sulfur Proteins
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IscU protein, E coli
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Sulfur
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Carbon-Sulfur Lyases
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cysteine desulfurase
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Cysteine