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Figure 5.
Figure 5 Active site variability and communication. (A)
Superposition of the active sites from the metal-ion bound
monomer (yellow) and the metal-free monomer (green). Significant
changes in conformation of side chains and in the order of
adjacent segments of the polypeptide chain occur as a result of
metal ion binding. (B) A pathway for communication between the
two active sites is provided by the direct interaction of the
N-termini of helix 4 at the dimer interface. These are directly
linked to the flexible 'pin' segments, which in turn connect to
the active site metal ion ligand Glu117. Changes in the
conformation of one active site would be communicated to the
other site via this pathway, and could mediate the positive
cooperativity observed between the first and second strand
cleavage reactions.
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