Journal:JBIC:10

Crystal structures of the all cysteinyl coordinated D14C variant of Pyrococcus furiosus ferredoxin: [4Fe-4S] <-> [3Fe-4S] cluster conversion

Monika Nøhr Løvgreen, Maja Martic, Michael S. Windahl, Hans E. M. Christensen and Pernille Harris^[1]

Molecular Tour
Structures of the all cysteinyl coordinated D14C variant of ferredoxin from the hyperthermophilic archaeon Pyrococcus furiosus have been determined for the <-> and forms (). The [4Fe-4S] form diffracted to 1.7 Å and two different types of molecules were found in the crystal (2z8q). They have different crystal packing and intramolecular disulfide bond conformation. The crystal packing reveals a (shown in blue and green) in adjacent asymmetric units, while (shown in red and yellow). The while the intramolecular disulfide bond in the (, molecule A is shown in blue and molecule B in green).

pH dependent equilibrium of D14C [3Fe-4S] P. furiosus ferredoxin between protonated and deprotonated monomers and formation of a disulfide bonded dimer from 6 deprotonated monomers. Fd is short for ferredoxin.

Two forms of D14C [3Fe-4S] Pyrococcus furiosus ferredoxin are obtained when purified at pH 8.0: a monomer and a dimer connected by an intermolecular disulfide bond. When purified at pH 5.8, only the monomer is obtained. The [3Fe-4S] form diffracted to 2.8 Å resolution and showed only the monomeric form, which resembles molecule A of D14C [4Fe-4S] Pyrococcus furiosus ferredoxin.