Traditional approaches for the development of toolboxes for genetically engineering host strains have been applied in nonconventional yeasts to extend protein production capacity, improve product quality, and ease downstream processing (Krainer ., 2014).Combining recent advances in molecular and genetic resources with the scale-up processes of high cell-density cultivation in various yeast species increases the diversity of choices for yeast expression systems in which recombinant protein production and optimization can be performed quickly and efficiently.
In recent times, the industrial importance of yeasts has extended beyond its traditional use in fermentation into various healthcare sectors, such as in the production of therapeutic recombinant proteins.
Yeast cells are particularly advantageous as hosts for biopharmaceutical production in that they are generally recognized as safe (GRAS) organisms.
The use of yeasts enables an ideal combination of hardy growth on simple media in large-scale bioreactors with the capacity of the desired post-translational modifications and feasibility in genetic manipulations (Mattanovich , make them practical alternative hosts for biotechnological purposes.
The biopharmaceutical products produced in various yeast species, which are on the market or in the final stages of development, are summarized in Table 2.
Yeasts are capable of robust growth on simple media, readily accommodate genetic modifications, and incorporate typical eukaryotic post-translational modifications.
have gained increasing attention as alternative hosts for the industrial production of recombinant proteins.However, native promoters may not offer continual gradients of transcriptional strength, thereby limiting the ability to fine-tune gene expression.In recent years, significant efforts have been made to develop constitutive promoters exhibiting a wide range of transcriptional activities.The estimated market value of biopharmaceuticals, including recombinant therapeutic proteins, nucleic acid-based products, and engineered cell-based products, is , and mammalian cells are the most widely used host systems for biopharmaceutical protein production, accounting for 15%, 31%, and 43% of biopharmaceutical products developed, respectively (Berlec and Strukelj 2013).The main strength of often results in inclusion body formation and/or low specific yields.Moreover, galactose is a relatively expensive carbon source, further limiting the benefits of promoter with six Zif268 binding sites showed that this synthetic promoter, in the presence of an agonist β-estradiol that binds to and activates the transcriptional activity of estrogen receptor, was able to control gene expression levels with greater sensitivity in EV factor was constructed by fusion of the Zif268 DNA-binding domain containing three zinc fingers, the ligand binding domain of the human estrogen receptor, and viral protein 16 from herpes simplex virus (Mc Isaac ) is the most frequently utilized strong and tightly controlled promoter.Because the use of toxic and inflammable methanol can pose a considerable safety risk in industrial settings, this promoter has been extensively studied to create synthetic variants with increased promoter strength and altered methanol-free regulation (Vogl and Glieder 2013). All living organisms use synonymous codons with variable frequencies that encode specific amino acid residues, although different organisms use alternative redundant codons for a given amino acid with differing efficacy.These tools can target different levels in biosynthetic processes and allow multilevel modifications of yeast host strains to improve the quality and yield of recombinant proteins.Efficient transcription is a critical step in controlling gene expression at the initial stage.In this review, we address the established and emerging genetic tools and host strains suitable for recombinant protein production in various yeast expression systems, particularly focusing on current efforts toward synthetic biology approaches in developing yeast cell factories for the production of therapeutic recombinant proteins.Yeasts have been used for thousands of years in food and fermentation processes to produce alcoholic beverages and breads.