Robust expression of a bioactive mammalian protein in Chlamydomonas chloroplast

Andrea L. Manuell, Maria Verónica Beligni, John H. Elder, David T. Siefker, Miller Tran, Annika Weber, Thomas L. McDonald, Stephen P. Mayfield

Research output: Contribution to journalArticlepeer-review

146 Scopus citations


We have engineered the chloroplast of eukaryotic algae to produce a number of recombinant proteins, including human monoclonal antibodies, but, to date, have achieved expression to only 0.5% of total protein. Here, we show that, by engineering the mammalian coding region of bovine mammary-associated serum amyloid (M-SAA) as a direct replacement for the chloroplast psbA coding region, we can achieve expression of recombinant protein above 5% of total protein. Chloroplast-expressed M-SAA accumulates predominantly as a soluble protein, contains the correct amino terminal sequence and has little or no post-translational modification. M-SAA is found in mammalian colostrum and stimulates the production of mucin in the gut, acting in the prophylaxis of bacterial and viral infections. Chloroplast-expressed and purified M-SAA is able to stimulate mucin production in human gut epithelial cell lines. As Chlamydomonas reinhardtii is an edible alga, production of therapeutic proteins in this organism offers the potential for oral delivery of gut-active proteins, such as M-SAA.

Original languageEnglish (US)
Pages (from-to)402-412
Number of pages11
JournalPlant Biotechnology Journal
Issue number3
StatePublished - May 2007


  • Chloroplast genetic engineering
  • Orally available biologics
  • Protein therapeutics
  • Recombinant protein expression in algae

ASJC Scopus subject areas

  • Biotechnology
  • Agronomy and Crop Science
  • Plant Science


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