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Figure 3.
Fig. 3. Domain movements in monomeric SecA. Ribbon diagram
of monomeric B. subtilis SecA in the open conformation (a) and
of a single subunit of dimeric B. subtilis SecA in the closed
conformation (b). Color codes are as described for Fig. 1. The
first and last helices in the PPXD are represented as cylinders
to better visualize the transition between the conformations.
The arrows in a indicate the movements that are required to
convert the open conformation to the closed conformation. The
side chains of residues 232 and 773 are shown in red in stick
representation. Corresponding E. coli SecA residue numbers are
given in parentheses. These residues were mutated to cysteines
in E. coli SecA, and the accessibility of residue 824 to a
modification reagent was used to probe the transition from the
closed to the open conformation.
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