C-terminal extension of truncated recombinant proteins in Escherichia coli with a 10Sa RNA decapeptide

J Biol Chem. 1995 Apr 21;270(16):9322-6. doi: 10.1074/jbc.270.16.9322.


When murine interleukin-6 is overexpressed in Escherichia coli, a small population of molecules exhibits a novel C-terminal modification. Peptide mapping, electrospray ionization-mass spectrometry, and automated N- and C-terminal sequencing identified a peptide ("tag" peptide), -Ala-Ala-Asn-Asp-Glu-Asn-Tyr-Ala-Leu-Ala-Ala-COOH, encoded by a small metabolically stable RNA of E. coli (10Sa RNA) attached to truncated C termini of the recombinant protein. A mutant strain of E. coli in which the chromosomal 10Sa RNA gene (ssrA) is disrupted does not produce this C-terminal modification, confirming that the tag peptide originates from the ssrA gene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Escherichia coli / genetics*
  • Interleukin-6 / biosynthesis*
  • Molecular Sequence Data
  • Oligopeptides / biosynthesis*
  • RNA, Bacterial / genetics*
  • Recombinant Proteins / biosynthesis*


  • Interleukin-6
  • Oligopeptides
  • RNA, Bacterial
  • Recombinant Proteins