Synthetic Orthogonal Promoters and Transcription Factor Platforms in Algae: Rational Design Principles and Applications in Synthetic Biology

Algae biomass and cellular exudated compounds have several biotechnological applications in various areas, such as agriculture, pharmaceutical, human and animal feed, and bioenergy, among others. However, many of these applications have not been developed to their full capability, in part due to the need to better understand the underlying principles of their cellular regulation of growth and metabolism. Recently, synthetic biology has been implemented as a new option to not only build new biological devices and systems but also comprehend the natural biochemical pathways present in living organisms. The use of this technology is still underdeveloped in algae research when compared to yeast and bacterial applications. Part of this effect is due to restraints on building multi-gene circuits, which are associated with the lack of controllable promoters and transcription factors in algae. This scenario could be improved by the development of orthogonal gene promoters, supported by the understanding of global biological responses related to their function in the host metabolism. With the integrative analysis of genomics, transcriptomics and proteomics, we may be able to find patterns of optimal orthogonality and address the rational design of optimal gene promoters that enhance algae biotechnological applications. In this paper, we will review the existing approaches and discuss future perspectives on the creation of orthogonal gene promoters in algae.