Table 1.
Strategies to reduce proteolysis in plant tissues and cell cultures.
| Target protease(s) | Production host | Protein of interest | Effect on accumulation level | References | ||
|---|---|---|---|---|---|---|
| Supplementation of stabilizing agents | Gelatin or polyvinylpyrrolidone | N. tabacum hairy roots | Murine IgG1 antibody | 9-fold increase | Wongsamuth and Doran, 1997 | |
| Polyvinylpyrrolidone | N. tabacum NT-1 cells | Murine IgG1 antibody | 35-fold increase | LaCount et al., 1997 | ||
| BSA | N. tabacum NT-1 cells | hGM-CSF | 2-fold increase | James et al., 2000 | ||
| HSA | P. patens | Human VEGF | 3-fold increase | Baur et al., 2005 | ||
| Co-expression of protease inhibitors | Cathepsin D inhibitor (SlCDI) | Serine (S1) and aspartic proteases (A1) | S. tuberosum | α1-anti-chymotrypsin | 2.5-fold increase | Goulet et al., 2010b |
| SlCDI or tomato cystatin SlCYS9 | SlCDI: serine (S1) and aspartic (A1) proteases. SlCYS9: cysteine proteases (C1, C13) | N. benthamiana | C5-1 IgG monoclonal antibody | Up to 70–80% increase of antibody light chain | Goulet et al., 2012 | |
| SlCDI | Serine (S1) and aspartic proteases (A1) | N. benthamiana | C5-1 IgG monoclonal antibody | Up to 85% increase of antibody heavy chain | Goulet et al., 2012 | |
| SlCYS8 | Cysteine proteases (C1) | N. benthamiana | C5-1 IgG monoclonal antibody | Up to 40% increase of mAb | Robert et al., 2013 | |
| Oryzacystatin-I | Cysteine proteases (C1) | N. tabacum | Glutathione reductase (GR) | Increase of GR accumulation level not specified | Pillay et al., 2012 | |
| Proteinase inhibitor II | Serine proteases (S1, S8) | O. sativa suspension cells | hGM-CSF | 2-fold increase | Kim et al., 2008b | |
| Bowman-Birk serine protease inhibitor | Serine proteases (S1) | N. tabacum roots | Human single-chain IgG1 or full-size IgG4 | 2-2.5 fold increase | Komarnytsky et al., 2006 | |
| Gene knockdown | ihpRNA construct specific to Rep-1 | Cysteine proteases (C1) | O. sativa suspension cells | hGM-CSF | 2-fold increase | Kim et al., 2008a |
| Expression of antisense sequences | Aspartic (A1), cysteine (C1), metallo- (M10) and serine proteases (S8) | N. tabacum BY-2 cells | IgG1κ antibody 2F5 | 4-fold increase of the intact antibody heavy chain | Mandal et al., 2014 | |
| RNAi construct specific to CysP6 | Cysteine protease (C1) | N. tabacum | Human IL-10 | 1.6-fold increase | Duwadi et al., 2015 | |
| Fusion proteins | Fusion of Zera domain | N. tabacum NT-1 cells | Zera domain fused subunit vaccine F1-V | 3-fold increase | Alvarez et al., 2010 | |
| Fusion of SlCYS8 | N. benthamiana | SlCYS8 fused α1-ACT | 25-fold increase | Sainsbury et al., 2013 | ||