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Figure 8.
Figure 8. Ribbon diagrams of the peroxidatic active sites.
The typical 2-Cys Prx adopts (a) fully folded (PDB ID 1QMV)17
and (b) locally unfolded (1QQ2)16 conformations that are
correlated with the catalytic cycle. In the recycling step, a
dramatic structural rearrangement occurs in order to allow C[P]
and C[R] to react and form a disulfide, through the local
unfolding of the a2 region and the C-terminal domain. (c) The A.
pernix archaeal Prx structure in the fully folded conformation
(2CV4, this study). Multiple conformations of the flexible
region III (residues 197-206) from ten monomers are drawn in the
Figure. The intra-monomer C207-S-S-C[R]213 minimizes the
conformational flexibility of region III and suppresses the
structural rearrangement leading to the locally unfolded
conformation. (d) A model of the locally unfolded conformation
for the A. pernix archaeal Prx. The breakage of the
intra-monomer C207-S-S-C[R]213 by unknown electron donor(s)
would induce the structural rearrangement so that C[R]213-SH can
access and react with the C[P]50-SOH, to form the inter-monomer
C[P]50-S-S-C[R]213. Helices and b-strands of monomer A are blue
and cyan, and those of monomer B are red and pink.
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