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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
12
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pubmed:dateCreated |
2000-4-27
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pubmed:abstractText |
ThiI is an enzyme common to the biosynthetic pathways leading to both thiamin and 4-thiouridine in tRNA. Comparison of the ThiI sequence with protein sequences in the data bases revealed that the Escherichia coli enzyme contains a C-terminal extension displaying sequence similarity to the sulfurtransferase rhodanese. Cys-456 of ThiI aligns with the active site cysteine residue of rhodanese that transiently forms a persulfide during catalysis. We investigated the functional importance of this sequence similarity and discovered that, like rhodanese, ThiI catalyzes the transfer of sulfur from thiosulfate to cyanide. Mutation of Cys-456 to alanine impairs this sulfurtransferase activity, and the C456A ThiI is incapable of supporting generation of 4-thiouridine in tRNA both in vitro and in vivo. We therefore conclude that Cys-456 of ThiI is critical for activity and propose that Cys-456 transiently forms a persulfide during catalysis. To accommodate this hypothesis, we propose a general mechanism for sulfur transfer in which the terminal sulfur of the persulfide first acts as a nucleophile and is then transferred as an equivalent of S(2-) rather than S(0).
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pubmed:grant |
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Bacterial Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Cyanides,
http://linkedlifedata.com/resource/pubmed/chemical/Escherichia coli Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/RNA, Transfer,
http://linkedlifedata.com/resource/pubmed/chemical/Sulfides,
http://linkedlifedata.com/resource/pubmed/chemical/Sulfurtransferases,
http://linkedlifedata.com/resource/pubmed/chemical/ThiI protein, bacteria,
http://linkedlifedata.com/resource/pubmed/chemical/Thiamine,
http://linkedlifedata.com/resource/pubmed/chemical/Thiosulfate Sulfurtransferase,
http://linkedlifedata.com/resource/pubmed/chemical/Thiosulfates,
http://linkedlifedata.com/resource/pubmed/chemical/Thiouridine,
http://linkedlifedata.com/resource/pubmed/chemical/persulfides,
http://linkedlifedata.com/resource/pubmed/chemical/thiI protein, E coli
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pubmed:status |
MEDLINE
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pubmed:month |
Mar
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pubmed:issn |
0021-9258
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
24
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pubmed:volume |
275
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
8283-6
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:10722656-Amino Acid Sequence,
pubmed-meshheading:10722656-Bacterial Proteins,
pubmed-meshheading:10722656-Cyanides,
pubmed-meshheading:10722656-Escherichia coli Proteins,
pubmed-meshheading:10722656-Models, Chemical,
pubmed-meshheading:10722656-Molecular Sequence Data,
pubmed-meshheading:10722656-RNA, Transfer,
pubmed-meshheading:10722656-Sequence Homology, Amino Acid,
pubmed-meshheading:10722656-Sulfides,
pubmed-meshheading:10722656-Sulfurtransferases,
pubmed-meshheading:10722656-Thiamine,
pubmed-meshheading:10722656-Thiosulfate Sulfurtransferase,
pubmed-meshheading:10722656-Thiosulfates,
pubmed-meshheading:10722656-Thiouridine
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pubmed:year |
2000
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pubmed:articleTitle |
Evidence that ThiI, an enzyme shared between thiamin and 4-thiouridine biosynthesis, may be a sulfurtransferase that proceeds through a persulfide intermediate.
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pubmed:affiliation |
Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, U.S. Gov't, Non-P.H.S.
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