Plug & play - developing tuneable gene expression in microalgae using synthetic biology approaches

Abstract: There is enormous potential to use microalgae as feedstocks for everything from recombinant proteins and high value chemicals to biofuels, but to implement this technology in a sustainable and economic manner, it will be necessary to optimize many parameters, and metabolic engineering strategies will be essential. However, in comparison with the well-developed molecular biology approaches available for manipulation of bacteria, yeast, and even land plants, those for algae are limited, even for the well-studied Chlamydomonas reinhardtii. We are interested in developing tools for genetic circuits using endogenous regulatory systems. Thiamine pyrophosphate (TPP) riboswitches are regions in messenger RNA that bind to TPP directly without the involvement of protein factors. Alternative splicing of the transcript then leads to changes in expression of the downstream open reading frame. Using our synthetic biology workflow we have investigated the mechanism of action of these sequences, and demonstrated that they can control transgene expression at nM concentrations of thiamine added to the cultures. By changing the aptamer sequence – the region that binds the TPP ligand – we can alter the sensitivity to different thiamine analogues.  By this means we aim to generate a suite of riboswitches that can ‘tune’ expression of one or more transgenes.

Host: Luke Mackinder