Figure 7.

The mature region of prFd-protA_His preferentially contacts the dimer interface of AtToc159G. A, prFd-protA_His was incubated with various [³⁵S]Met-labeled single-Cys AtToc159G mutants. After BMH cross-linking, reactions were analyzed by SDS-PAGE and fluorography. The locations of the single Cys residues are indicated above the lanes. Cys-864 and Cys-951 are located around FeBABE cleavage site 1 on the dimer interface, whereas Cys-917, Cys-920, and Cys-924 are located around cleavage site 2 in the switch II region. The cross-linked adduct of AtToc159G-prFd-protA_His is indicated by an arrow. A nonspecific cross-linked product from a protein in the reticulocyte lysate is indicated by the asterisk. B, Binding and cross-linking experiments were performed as described in A, except that prFd-protA_His (-37S/C) was used. Quantification of the cross-linked products is shown at right for each preprotein. The value for each single-Cys AtToc159G preprotein cross-linked product was normalized to the amount of cross-linking observed for AtToc159G Cys-864 to the same preprotein. Values plotted are means ± sd of three independent experiments.