Proteomic analysis reveals molecular changes following genetic engineering in Chlamydomonas reinhardtii

Background: Chlamydomonas reinhardtii is gaining recognition as a promising expression system for the production of recombinant proteins. However, its performance as a cellular biofactory remains suboptimal, especially with respect to consistent expression of heterologous genes. Gene silencing mechanisms, position effect, and low nuclear transgene expression are major drawbacks for recombinant protein production in this model system. To unveil the molecular changes following transgene insertion, retention, and expression in this species, we genetically engineered C. reinhardtii wild type strain 137c (strain cc-125 mt+) to express the fluorescent protein mVenus and subsequently analysed its intracellular proteome. Results: The obtained transgenic cell lines showed differences in abundance in more than 400 proteins, with multiple pathways altered post-transformation. Proteins involved in chromatin remodelling, translation initiation and elongation, and protein quality control and transport were found in lower abundance. On the other hand, ribosomal proteins showed higher abundance, a signal of ribosomal stress response. Conclusions: These results provide new insights into the modifications of C. reinhardtii proteome after transformation, highlighting possible pathways involved in gene silencing. Moreover, this study identifies multiple protein targets for future genetic engineering approaches to improve the prospective use of C. reinhardtii as cell biofactory for industrial applications.