Order of fusions between bacterial and mammalian proteins can determine solubility in Escherichia coli

Deepali Sachdev, John M. Chirgwin

Research output: Contribution to journalArticle

48 Scopus citations


We made fusions between Escherichia coil maltose-binding protein (MBP) and the mammalian aspartic proteinases pepsinogen or procathepsin D. When MBP was at the N-terminus, the fusions were soluble in E. coil. When the order was reversed, the chimeric proteins formed inclusion bodies. The data suggest that the solubility of fusion proteins is controlled by whether the protein domains emerging first from the ribosome normally fold into soluble or insoluble states. The soluble MBP-aspartic proteinase fusions were stable but proteolytically inactive. MBP-pepsinogen, however, was efficiently renatured from 8 M urea in vitro, suggesting that the E. coli cytoplasm does not support folding of the mammalian partner protein to the native state. Thus, inclusion body formation may be the consequence, rather than the cause, of non-native folding in vivo and in E. coil soluble proteins may fold into states different from those reached in vitro.

Original languageEnglish (US)
Pages (from-to)933-937
Number of pages5
JournalBiochemical and Biophysical Research Communications
Issue number3
StatePublished - Mar 27 1998


ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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