Normal precursors of periplasmic proteins accumulated in the cytoplasm are not exported post-translationally in Escherichia coli

Eur J Biochem. 1984 Sep 17;143(3):499-505. doi: 10.1111/j.1432-1033.1984.tb08398.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism*
  • Binding Sites
  • Biological Transport
  • Carrier Proteins / biosynthesis
  • Carrier Proteins / metabolism*
  • Cytoplasm / metabolism*
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Immunochemistry
  • Peptides / metabolism
  • Phosphate-Binding Proteins
  • Protein Biosynthesis
  • Protein Precursors / metabolism*
  • Protein Sorting Signals


  • Bacterial Proteins
  • Carrier Proteins
  • Peptides
  • Phosphate-Binding Proteins
  • Protein Precursors
  • Protein Sorting Signals