Expression and characterization of the terminal heme synthetic enzymes from the hyperthermophile Aquifex aeolicus

The terminal two heme biosynthetic pathway enzymes, protoporphyrinogen oxid ase and ferrochelatase, of the hyperthermophilic bacterium Aquifex aeolicus have been expressed in Escherichia coli, purified to homogeneity, and bioc hemically characterized. Ferrochelatase and protoporphyrinogen oxidase of t his organism are both monomeric, as was found for the corresponding enzymes of Bacillus subtilis. However, unlike the B. subtilis proteins, both A. ae olicus enzymes are membrane-associated. Both proteins have temperature opti ma over 60 degreesC. This is the first demonstration of functional heme bio synthetic enzymes in an extreme thermophilic bacterium. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiolo gical Societies.