Project Description
“Every step of progress the world has made has been from scaffold to scaffold (...)”
Scaffococcus: Lactococcus scaffold
This year we genetically engineered a strain of the species Lactococcus lactis by introducing optimized genes of the bacterium Clostridium thermocellum. Our ultimate goal was to obtain an organism capable of expressing a customizable extracellular platform that could harbour a very wide range of enzymes that, in turn, would be able to carry out a seemingly endless variety of metabolic processes. Due to its high potential for further engineering, we believe the scaffold to be a very important advancement in the biotechnology landscape.
We believe the scaffold to have many serious implications, since it may tackle many different issues such as customizing and facilitating the creation of synthetic metabolic pathways, and the processing of substrates in industrial processes.
The implications are:
Increased Efficiency
For many metabolic processes happening in the cell, the enzymatic substrate must be imported into the cytoplasm for processing. This usually requires energy from the cell, which diminishes the efficiency of the process. In the same way, if the metabolic product of such a reaction would be of interest, the organism would require a way to excrete it, which is, again, energetically consuming. With an external scaffold holding these enzymes in place, the import of substrate and export of product would be bypassed, and therefore the efficiency of a certain enzymatic process could be increased or facilitated.
Ordered Multi-step Processes
With the scaffold it is possible to recreate or engineer diverse multi-step processes with high efficiency. Imitating the naturally occurring process of enzyme channeling, emulating multi-enzyme complexes and programming seemingly complex metabolic processes are only some of the many possible advantages of the scaffold.
Fusion of Non-prokaryotic Proteins to Scaffold
Many proteins that have potential scientific or industrial interest are difficult or impossible to express in prokaryotic organisms in a useful manner. Eukaryotic enzymes could be expressed in some other organisms, like yeast, and displayed extracellularly on the bacterial scaffold, giving a whole new toolkit to researchers and companies alike.
The Alcohol-to-Carboxylic-Acid Pathway
We believe that one of the strongest points about the scaffold is its ability to harbor proteins in an ordered fashion. This feature alone will have a huge impact on the engineering of processes, since artificial metabolic pathways can be tailored for specific needs, and then displayed on the scaffold for diverse industrial and research purposes. To affirm this presumption, we decided to build a metabolic pathway that could be easily measurable and in which the scaffold’s contribution to its efficiency could be readily measurable.
We prototyped the alcohol-to-carboxylic-acid pathway, which was thought to transform ethanol into acetic acid through a two-step mechanism. We displayed alcohol dehydrogenase and aldehyde dehydrogenase sequentially onto the scaffold which would, in principle, yield the desired compound in an efficient manner. The efficiency of the pathway would be readily measurable by assaying the production of the pathway’s final product, acetic acid.
