Fate of the (2Fe-2S)2+ Cluster of Escherichia coli Biotin Synthase during Reaction: A Mössbauer Characterization
| Autor: | Andrée Marquet, Riidiger Benda, Volker Schünemann, Alfred X. Trautwein, Bernadette Tse Sum Bui, Dominique Florentin |
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| Rok vydání: | 2003 |
| Předmět: |
Flavodoxin
Stereochemistry Iron Biotin synthase Dithionite Biochemistry Spectroscopy Mossbauer chemistry.chemical_compound Biotin Biosynthesis Escherichia coli chemistry.chemical_classification Flavin adenine dinucleotide Dose-Response Relationship Drug biology Substrate (chemistry) Enzyme Models Chemical chemistry Ammonium Sulfate Sulfurtransferases Flavin-Adenine Dinucleotide biology.protein NADP Sulfur Subcellular Fractions |
| Zdroj: | Biochemistry. 42:8791-8798 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi034426c |
| Popis: | Biotin synthase, the enzyme which catalyzes the last step of the biosynthesis of biotin, contains only (2Fe-2S)(2+) clusters when isolated under aerobic conditions. Previous results showed that reduction by dithionite or photoreduced deazaflavin converts the (2Fe-2S)(2+) to (4Fe-4S)(2+,+). However, until now, no detailed investigation concerning the fate of the (2Fe-2S)(2+) during reduction under assay conditions (NADPH, flavodoxin, flavodoxin reductase) has been realized. Here, we show by Mössbauer spectroscopy on a partially purified fraction overexpressing the enzyme that, in the presence of a S(2)(-) source and Fe(2+), there is conversion of the predominant (2Fe-2S)(2+) clusters into a 1:1 mixture of (2Fe-2S)(2+) and (4Fe-4S)(2+). No change in this cluster composition was observed in the presence of the physiological reducing system. When the reaction was allowed to proceed by addition of the substrate dethiobiotin, the (4Fe-4S)(2+) was untouched whereas the (2Fe-2S)(2+) was degraded into a new species. This is consistent with the hypothesis that the reduced (4Fe-4S) cluster is involved in mediating the cleavage of AdoMet and that the (2Fe-2S)(2+) is the sulfur source for biotin. |
| Databáze: | OpenAIRE |
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