Redox Enzyme Wiring to Surfaces

The interface between the organic (or biological) to the inorganic is one of the major focuses of our lab. Enzymes or proteins that are efficiently coupled with electrodes made of metals or graphene, are the basis for many types of devices that enable electron communication with electrodes. One of the most basic hypotheses in the lab was that by orienting redox enzymes on electrodes to afford a minimal distance for electron transfer to the redox active-site in the protein, electron injection or electron withdrawal will become very efficient and will allow a potentiometric control of the enzyme activity. When the attachment is done through a single point, the interference with the protein/enzyme folding becomes minimal. Such devices can be enzyme-based biosensors, enzyme-based fuel-cells, autonomous biosensing devices and wearable biosensing devices.

Enzymes that we have site-specifically wired to electrodes are: Copper efflux oxidase from E. coli (CueO) and a fusion enzyme of glucose dehydrogenase with a minimal cytochrome domain (FGM).

A model of the FGM enzyme with the porphyrin of the minimal cytochrome in red and the glucose dehydrogenase domain in gold
Different points and modes of Attachment of FGM to an electrode
Electron transfer distances between the active site and the electrode
Copper efflux oxidase (CueO) and the different points through which it was attached to an electrode
Genetic Code Expansion in Different Microorganisms

In order to modify proteins and enzymes in different organisms, we have expanded the genetic code of the following microorganisms:

Synechoccocus Elongatus PCC7942
Pseudomonas aeruginosa
Vibrio Natriegens
Chlamydomonas reinhardtii

By expanding the genetic code of Pseudomonas aeruginosa we could now click to an unnatural amino acid a fluorophore and track flagella in a living biofilm:

Top view (left) and side view (right) of site-specifically labeled flagella
Planktonic cell of Pseudomonas aeruginosa with labeled flagella and GFP expressing bacteria
Flagella labeled in a biofilm
Overlay of GFP expressing cells with their labeled flagella in a biofilm with its mushroom like structures