Indolepyruvate ferredoxin oxidoreductase from Pyrococcus sp. KOD1 possesses a mosaic structure showing features of various oxidoreductases.

Indolepyruvate ferredoxin oxidoreductase (IOR) catalyzes the oxidative decarboxylation of arylpyruvates. Gene cloning and sequencing analysis of the IOR gene from the hyperthermophilic archaeon Pyrococcus sp. KOD1 was performed. Two genes, iorA and iorB. encoding alpha and beta subunits of IOR were found to be tandemly arranged, which suggests that gene expression is translationally coupled. Sequence analysis showed the C-terminal region of the alpha subunit to have a typical ferredoxin-type [4Fe-4S] cluster motif (CXXCXXCXXCXXXCP), which is similar to that present in the delta subunits of other oxidoreductases such as pyruvate ferredoxin oxidoreductase (POR) and 2-ketoisovalerate ferredoxin oxidoreductase (VOR). We suggest that the alpha subunit of KOD1-IOR has a mosaic structure composed of features characteristic of the alpha, beta and delta subunits from POR and VOR. KOD1-IOR was overproduced in anaerobically incubated Escherichia coli cells and the crude enzyme was extracted under anaerobic conditions. The optimal temperature for activity of recombinant IOR was 70 degrees C and the half-life of this enzyme in the presence of air was 15 min at 25 degrees C.