Our aim was to transport Vitamin B₁₂, a substance which has no known cellular exporter in nature, through the inner membrane out of the cytoplasm.

Our different B₁₂ Synporter proteins consist of TorA signal peptide for a Twin Arginine Transporter (Tat) mediated export that is linked to a B₁₂-binding domain. This construct was produced, together with B₁₂, by the B₁₂ autotrophic R. planticola and S. blattae. First, we could show that the Synporter proteins were translocated into the periplasm. Moreover, most important, we could also prove the enrichment of B₁₂ in the periplasm, which proofs that our Synporter is functional.

Thereby, Vitamin B₁₂ can also be regarded as a prime example which is what we want to state with our work. In principle, a Synporter should work with basically any desired chemical, if a non-covalently protein counterpart exists which can be used as the binding domain. This might for instance be achieved using directed evolution for nanobodies.

WIthin our work, we were the first ... that a high-molecular compound as B₁₂ was translocated through a cellular membrane without a native exporter, which makes our Synporter so innovative.

This concept can be applied for the production of all natural chemicals which are synthesized, but not exported due to the lack of a cellular exporter. Furthermore, it can also be applied for the production of artificial molecules which can be produced by synthetic metabolic engineering in a cell. Using our Synporter approach, no cell lysis is required any more for the industrial production, which makes the production process significantly easier and cheaper.