Normal precursors of periplasmic proteins accumulated in the cytoplasm are not exported post-translationally in Escherichia coli.
Hyperproduction of phosphate-binding protein, PhoS, in strains carrying a multicopy plasmic containing the phoS gene, resulted in saturation of export sites. As a consequence, pre-PhoS was accumulated both in the inner membrane and in the cytoplasm. This was evidenced both in electron-microscopy and after cell fractionation. Only the membrane-associated precursor could be matured and exported. The signal sequence of the cytoplasmic pre-PhoS was slowly degraded. It was first cleaved about in its middle and then completely removed. Electron microscope studies demonstrated that the cytoplasmic pre-PhoS cannot be exported post-translationally.
D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites; D001692:Biological Transport; D002352:Carrier Proteins / Q000096:biosynthesis / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D007120:Immunochemistry; D010455:Peptides / Q000378:metabolism; D028044:Phosphate-Binding Proteins; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000378:metabolism*; D021382:Protein Sorting Signals
D001426:Bacterial Proteins; D002352:Carrier Proteins; D010455:Peptides; D028044:Phosphate-Binding Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals