Expression, purification, and biophysical characterization of a secreted anthrax decoy fusion protein in nicotiana benthamiana

Kalimuthu Karuppanan, Sifti Duhra-Gill, Muchena J. Kailemia, My L. Phu, Carlito B Lebrilla, Abhaya M. Dandekar, Raymond L. Rodriguez, Somen Nandi, Karen A. McDonald

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Anthrax toxin receptor-mediated drug development for blocking anthrax toxin action has received much attention in recent decades. In this study, we produced a secreted anthrax decoy fusion protein comprised of a portion of the human capillary morphogenesis gene-2 (CMG2) protein fused via a linker to the fragment crystallizable (Fc) domain of human immunoglobulin G1 in Nicotiana benthamiana plants using a transient expression system. Using the Cauliflower Mosaic Virus (CaMV) 35S promoter and co-expression with the p19 gene silencing suppressor, we were able to achieve a high level of recombinant CMG2-Fc-Apo (rCMG2-Fc-Apo) protein accumulation. Production kinetics were observed up to eight days post-infiltration, and maximum production of 826 mg/kg fresh leaf weight was observed on day six. Protein A affinity chromatography purification of the rCMG2-Fc-Apo protein from whole leaf extract and apoplast wash fluid showed the homodimeric form under non-reducing gel electrophoresis and mass spectrometry analysis confirmed the molecular integrity of the secreted protein. The N-glycosylation pattern of purified rCMG2-Fc-Apo protein was analysed; the major portion of N-glycans consists of complex type structures in both protein samples. The most abundant (>50%) N-glycan structure was GlcNAc2(Xyl)Man3(Fuc)GlcNAc2 in rCMG2-Fc-Apo recovered from whole leaf extract and apoplast wash fluid. High mannose N-glycan structures were not detected in the apoplast wash fluid preparation, which confirmed the protein secretion. Altogether, these findings demonstrate that high-level production of rCMG2-Fc-Apo can be achieved by transient production in Nicotiana benthamiana plants with apoplast targeting.

Original languageEnglish (US)
Article number89
JournalInternational Journal of Molecular Sciences
Issue number1
StatePublished - Jan 4 2017


  • Anthrax decoy fusion protein
  • Apoplast wash fluid
  • N-glycosylation
  • Nicotiana benthamiana
  • Transient protein expression

ASJC Scopus subject areas

  • Catalysis
  • Molecular Biology
  • Computer Science Applications
  • Spectroscopy
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry


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