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Figure 1.
Ribbon representation of the PsrABC dimer viewed parallel to
the membrane, with one monomer shown in light gray for clarity.
The PsrA, PsrB and PsrC subunits in the monomer to the left are
green, ruby and blue, respectively. The MGD cofactors are orange
with molybdenum shown as a black sphere. Five [4Fe-4S] clusters
are shown in red (iron atoms) and yellow (sulfur atoms), and PCP
is shown in black. All distances, including edge-to-edge
distances between redox centres, are in given in angstroms. In
the catalytic cycle of Psr, menaquinol is reduced on the
periplasmic side of the membrane, releasing two protons and
electrons (dotted line). The electrons are transported via the
iron-sulfur clusters to the active-site molybdenum, where
polysulfide is reduced with the evolution of hydrogen sulfide.
All structural figures were made using PyMol
(http://pymol.sourceforge.net/).
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