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 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 (see static image at the left). 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 . Crystal packing in (shown in red and orange), which is the same as (1sj1, shown in blue and cyan) even though the space groups are different (see also corresponding side views for ) and ).