Protecting Recombinant Proteins from Degradation

Numerous systems have been devised over the last decade to develop plant biofactories producing recombinant pharmaceutical proteins. Scientists have successfully developed GM plants expressing antibodies, growth factors, hormones, cytokines, coagulation factors and vaccine antigens. Major advances have been made, in particular, in increasing transgene expression and elucidating the complex plant protein modification pathways. But the challenge of optimizing the yield and quality of recombinant proteins remains. Preventing unintended protein degradation is one of the ways to ensure satisfactory yield. However, this may prove to be difficult since recombinant proteins are generally less stable and have the tendency to produce multiple variants.

A paper published by the Plant Biotechnology journal reviews the current strategies to minimize protein degradation in plant biofactories. These include:

• Tissue-specific expression of the transgene
• Expression in specific cell compartments including the vacuole, chloroplast and ER
• Fusing the recombinant proteins with stabilizing partners
• Protein secretion in natural fluids
• Expression in plants with reduced protein-degrading enzymes
  

A case-by-case assessment involving the use of different strategies remains necessary given the individual characteristics of the proteins being expressed and plant biofactories being exploited.

The open access article is available at http://www.blackwell-synergy.com/doi/abs/10.1111/j.1467-7652.2008.00344.x