Fig. 5: The functions of TerC proteins MeeF and MeeY in exoenzyme metalation.
From: TerC proteins function during protein secretion to metalate exoenzymes
MeeF and MeeY are integral membrane proteins that function in Mn export15. MeeF and MeeY are here shown exporting Mn ion (purple circles) to support metalation of exoenzymes. MeeF and MeeY interact physically (co-immunoprecipitation) and genetically (epistasis with ftsH) with proteins of the secretosome. These results suggest that MeeF and MeeY function co-translocationally to insert Mn into nascent metalloproteins. As a result, meeF meeY (FY) double mutants are deficient in Sec-dependent secretion of exoenzymes (e.g., proteases, AprE, AmyQ), which leads to growth defects on LB medium. FY mutants are also deficient in activation of LTA synthases, which bind Mn to an extracellular catalytic domain. The essentiality of FtsH in the FY mutant is consistent with jamming of the SecYEG translocon. MeeF and MeeY may function as metallochaperones that directly transfer Mn to client proteins, and they may help generate a sufficiently high local Mn concentration to allow metalation. Created with BioRender.com.
