Harnessing the Algal Chloroplast for Heterologous Protein Production

Abstract

Photosynthetic microbes are gaining increasing attention as heterologous hosts for the light-driven, low-cost production of high-value recombinant proteins. Recent advances in the manipulation of unicellular algal genomes offer the opportunity to establish engineered strains as safe and viable alternatives to conventional heterotrophic expression systems, including for their use in the feed, food, and biopharmaceutical industries. Due to the relatively small size of their genomes, algal chloroplasts are excellent targets for synthetic biology approaches, and are convenient subcellular sites for the compartmentalized accumulation and storage of products. Different classes of recombinant proteins, including enzymes and peptides with therapeutical applications, have been successfully expressed in the plastid of the model organism Chlamydomonas reinhardtii, and of a few other species, highlighting the emerging potential of transplastomic algal biotechnology. In this review, we provide a unified view on the state-of-the-art tools that are available to introduce protein-encoding transgenes in microalgal plastids, and discuss the main (bio)technological bottlenecks that still need to be addressed to develop robust and sustainable green cell biofactories.

Chlamydomonas reinhardtii: A Factory of Nutraceutical and Food Supplements for Human Health

“…Moreover, the recombinant product’s efficient folding and accumulation can be achieved thanks to the chaperones and disulfide isomerase activities, which are able to support their native states. The procedures for product purification in C. reinhardtii can be significantly simplified thanks to its GRAS status and the absence of harmful viral, prion, or endotoxin contaminants [ 103 , 104 ].…”

Three Parts of the Plant Genome: On the Way to Success in the Production of Recombinant Proteins

“…Quite recently, major success was achieved in the production of fertile transplastomic Arabidopsis thaliana plants [ 156 ]. A wide range of proteins for different purposes are now effectively produced in transplastomic plants, and several dozen proteins are currently synthesized in chloroplasts, including recombinant vaccines, monoclonal antibodies, and various enzymes for therapeutic and industrial applications [ 157 , 158 , 159 , 160 ].…”

Chlamydomonas: Fast tracking from genomics

“…Chlamydomonas is also a model for understanding cilia/flagella and basal body biogenesis and their functions in motility and sensing the environment (Dutcher, 2020; Dutcher & O'Toole, 2016; Hayer‐Hartl, 2017; Ostrowski et al, 2011; Silflow & Lefebvre, 2001; Wostrikoff & Mackinder, 2023). It is increasingly used to dissect the cell cycle (Cross & Umen, 2015; Strenkert et al, 2019), nutrient limitation (Blaby‐Haas & Merchant, 2013; Calatrava et al, 2023; Sanz‐Luque & Grossman, 2023; Schmollinger et al, 2014), optogenetics (Berndt et al, 2016; Deisseroth & Hegemann, 2017), and interactions with other organisms (Calatrava et al, 2018; Torres et al, 2022) and in the production of recombinant proteins and high‐value chemicals, potentially in chloroplasts (Cutolo et al, 2022; Larrea‐Alvarez & Purton, 2021).…”