PS seminar: From the discovery of novel ABC transporters to their engineering for Synthetic Biology

Synthetic Biology provides enormous opportunities for humanity to re-engineer biology for applications that will redefine the way we live. Novel technologies based on repurposed and fully synthetic organisms, as well as cell-free biotechnologies (such as nanoreactors) are flourishing. Such technologies often depend on the generation of stable compartments with selective permeability. In living organisms, compartmentalization is conferred by lipid bilayer embedded with a wide range of transport proteins. Here I will focus on the energy-driven transporter family, the ATP-Binding Cassette (ABC) transporters, and how we can repurpose them for Biotechnology and Synthetic Biology applications.

A straightforward approach is to repurpose known transporters in heterologous systems. In this case, a prior knowledge of the transporters available “out there” is critical. And that brings me to my PhD studies where I characterized the NON-INTRINSIC ABC PROTEIN 13 and 14 from Arabidopsis. This work led to the discovery of a novel multi-subunit ABC transporter at the chloroplast inner envelope, from which the substrate remains to be identify.

A second approach is to engineer existing transporters towards a different substrate specificity. A great option if non-natural compounds are to be transported. In my current project, I am characterizing the metal-glutathione exporter ATM1 from the bacterium Novosphingobium aromaticivorans. Site-directed mutagenesis in the binding pocket followed by reconstitution in liposomes is used to assess how related substrates stimulate ATP hydrolysis. Future efforts will focus on developing a direct transport assay and building up a better knowledge around how substrate specificity could be rationally engineered.

Sarah was awarded her PhD in Plant Molecular Biology and Biochemistry in 2016 from the University of Neuchâtel, Switzerland. Her PhD project revolved around chloroplast lipid droplets and their essential role in thylakoid metabolism. Besides describing a Carotenoid Cleavage Dioxygenase (CCD4), she also studied a novel multi-subunit ABC transporter and its potential role in lipid translocation.

Since then she holds a CSIRO Research Plus Postdoctoral Fellowship in the Biocatalysis and Synthetic Biology Team, where she is developing technologies to engineer bacterial ABC transporters for Synthetic Biology applications.