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. Author manuscript; available in PMC: 2009 Mar 1.
Published in final edited form as: Arch Biochem Biophys. 2007 Dec 10;471(1):32–41. doi: 10.1016/j.abb.2007.12.001

Figure 6.

Figure 6

The fate of biotin synthase following catalysis. The active enzyme contains both [2Fe-2S]2+ and [4Fe-4S]2+/+ clusters; turnover with dethiobiotin and 2 equiv. of AdoMet results in the loss of the [2Fe-2S]2+ cluster. In the absence of substrates, the [4Fe-4S]2+/+ cluster is highly susceptible to oxidative degradation, leading to the formation of the less stable apoBioB, which is prone to ATP-dependent proteolytic degradation. In vivo, 4Fe-BioB could be rescued and returned to catalysis through reassembly of the [2Fe-2S]2+ cluster, a process that may be mediated by the Isc or Suf iron-sulfur cluster assembly systems.