(A) The proteolytically dead mutant YqgP.S288A behanes as a pseudoprotease and acts as a substrate adaptor of FtsH. Pattern of C-terminally truncated forms of endogenous MgtE formed in vivo in the presence of ectopically expressed active YqgP (strain BS72, Table EV2) or its inactive S288A mutant (BS73, Table EV2) in rich LB medium in the presence or absence of endogenous FtsH. Black arrow denotes the full-length MgtE substrate, and red arrows denote its cleavage products generated by YqgP. While the presence of the faster migrating YqgP-dependent products (full red arrows) do not depend on the presence of FtsH, the slower migrating product formed in the presence of YqgP.S288A (open red arrow) does, indicating that FtsH protease is responsible for the alternative cleavage of MgtE. The same arrow symbolics are valid throughout this figure. 