An in silico overview on the usefulness of tags and linkers in plant molecular pharming

Plant molecular pharming is a promising concept based on the large-scale production of recombinant proteins encompassing antibodies, vaccines and enzymes for human or veterinary uses and treatments. This new branch of biopharmaceutical industry offers pratcical and safety advantages over other traditional production systems. In higher plants, the complex cellular machinery makes possible synthesis and posttranslational modifications of heterologous protein macromolecules. The limiting obstacle to using this plant system at industrial scale is most often the low yield of the recombinant proteins. To improve this production level, many studies have been focusing on the choice of plant species, tissues, organs and cell suspension cultures or various upstream and downstream constituents in the expression cassettes. Likewise, new engineering technologies in plant molecular pharming have emerged relying on the usefulness of using soybean agglutinin (SBA), hydrophobin, zein and elastin-like peptide tags which are employed to extract and purify recombinant proteins in some host systems and under the control, and as a part, of different expression cassettes. Known to be very useful tools in recombinant proteins linkers separate different domains or units of the heterologous gene and thereby keep the functionality of the protein of interest. Here, we compare computationally one tag SBA as a part of fusion with a pharmaceutical human protein ADA joint directly or by the specific flexible (GGGGS)3 liker. The in silico analysis focuses on the mRNAs stability and fusions of tagged and tagged-linked ADA recombinant proteins

Molecular farming on rescue of pharma industry for next generations

Recombinant proteins expressed in plants have been emerged as a novel branch of the biopharmaceutical industry, offering practical and safety advantages over traditional approaches. Cultivable in various platforms (i.e. open field, greenhouses or bioreactors), plants hold great potential to produce different types of therapeutic proteins with reduced risks of contamination with human and animal pathogens. To maximize the yield and quality of plant-made pharmaceuticals, crucial factors should be taken into account, including host plants, expression cassettes, subcellular localization, post-translational modifications, and protein extraction and purification methods. DNA technology and genetic transformation methods have also contributed to great parts with substantial improvements. To play their proper function and stability, proteins require multiple post-translational modifications such as glycosylation. Intensive glycoengineering research has been performed to reduce the immunogenicity of recombinant proteins produced in plants. Important strategies have also been developed to minimize the proteolysis effects and enhance protein accumulation. With growing human population and new epidemic threats, the need for new medications will be paramount so that the traditional pharmaceutical industry will not be alone to answer medication demands for upcoming generations. Here, we review several aspects of plant molecular pharming and outline some important challenges that hamper these ambitious biotechnological developments

Recent advances on host plants and expression cassettes' structure

Plant molecular pharming is a promising system to produce important recombinant proteins such as therapeutic antibodies, pharmaceuticals, enzymes, growth factors, and vaccines. The system provides an interesting alternative method to the direct extraction of proteins from inappropriate source material while offering the possibility to overcome problems related to product safety and source availability. Multiple factors including plant hosts, genes of interest, expression vector cassettes, and extraction and purification techniques play important roles in the plant molecular pharming. Plant species, as a biosynthesis platform, are a crucial factor in achieving high yields of recombinant protein in plant. The choice of recombinant gene and its expression strategy is also of great importance in ensuring a high amount of the recombinant proteins. Many studies have been conducted to improve expression, accumulation, and purification of the recombinant protein from molecular pharming systems. Re-engineered vectors and expression cassettes are also pivotal tools in enhancing gene expression at the transcription and translation level, and increasing protein accumulation, stability, retention and targeting of specific organelles. In this review, we report recent advances and strategies of plant molecular pharming while focusing on the choice of plant hosts and the role of some molecular pharming elements and approaches: promoters, codon optimization, signal sequences, and peptides used for upstream design, purification and downstream processing