The lipoate synthase from Escherichia coli is an iron-sulfur protein

Lipoate synthase catalyzes the last step of the biosynthesis of lipoic acid in microorganisms and plants. The protein isolated from an overexpressing Escherichia coli strain was purified from inclusion bodies. Spectroscopic ( UV-visible and electron paramagnetic resonance) properties of the reconstit uted protein demonstrate the presence of a (2Fe-2S) center per protein. As observed in biotin synthase, these clusters are converted to (4Fe-4S) cente rs during reduction under anaerobic conditions, The possible involvement of the cluster in the insertion of sulfur atoms into the octanoic acid backbo ne is discussed. (C) 1999 Federation of European Biochemical Societies.