Iron-Sulfur Clusters of Biotin Synthase In Vivo: A Mössbauer Study

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• 作者：Rü ; diger Benda ; Bernadette Tse Sum Bui ; Volker Schü ; nemann ; Dominique Florentin ; André ; e Marquet ; and Alfred X. Trautwein
• 刊名：Biochemistry
• 出版年：2002
• 出版时间：December 17, 2002
• 年：2002
• 卷：41
• 期：50
• 页码：15000 - 15006
• 全文大小：139K
• 年卷期：v.41,no.50(December 17, 2002)
• ISSN：1520-4995

文摘

Biotin synthase, the enzyme that catalyzes the last step of the biosynthesis of biotin, containsonly [2Fe-2S]²⁺ clusters when isolated under aerobic conditions. Previous results showed that reconstitutionwith an excess of FeCl₃ and Na₂S under reducing and anaerobic conditions leads to either [4Fe-4S]²⁺,[4Fe-4S]⁺, or a mixture of [4Fe-4S]²⁺ and [2Fe-2S]²⁺ clusters. To determine whether any of thesepossibilities or other different cluster configuration could correspond to the physiological in vivo state,we have used ⁵⁷Fe Mössbauer spectroscopy to investigate the clusters of biotin synthase in whole cells.The results show that, in aerobically grown cells, biotin synthase contains a mixture of [4Fe-4S]²⁺ and[2Fe-2S]²⁺ clusters. A mixed [4Fe-4S]²⁺:[2Fe-2S]²⁺ cluster form has already been observed under certainin vitro conditions, and it has been proposed that both clusters might each play a significant role in themechanism of biotin synthase. Their presence in vivo is now another argument in favor of this mixedcluster form.