Expression of functional hexahistidine-tagged ricin B in tobacco

Plant Cell Rep. 2005 Apr;24(1):15-24. doi: 10.1007/s00299-004-0901-0. Epub 2004 Dec 15.


Ricin B (RTB), the lectin subunit of ricin, shows promise as an effective mucosal adjuvant and carrier for use in humans. In order to obtain a recombinant plant source of RTB that is devoid of the toxic ricin A subunit, we expressed RTB in Nicotiana tabacum. RTB was engineered with an N-terminal hexahistidine tag (His-RTB), which may affect protein stability. Lactose-affinity purification of His-RTB from leaves yielded three major glycosylated products of 32, 33.5 and 35 kDa. Their identity as RTB was verified by mass spectrometry and immunoblotting with anti-ricin antibodies. Functionality of His-RTB was confirmed by binding to asialofetuin, lactose and galactose.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Gene Expression / physiology*
  • Histidine / chemistry*
  • Oligopeptides / chemistry*
  • Plants, Genetically Modified
  • Recombinant Proteins / biosynthesis
  • Ricin / biosynthesis*
  • Ricin / chemistry
  • Ricin / genetics
  • Tobacco / genetics*
  • Tobacco / metabolism


  • His-His-His-His-His-His
  • Oligopeptides
  • Recombinant Proteins
  • Histidine
  • Ricin