MAXED OOT Maxicells; making a novel chassis maximised for use OOTside the lab

Why Synthetic Biology needs MaxED OOT Maxicells

Time and time again great feats of genetic engineering, that have the potential to solve innumerable global and local problems, must remain simply conceptual. It is often the risk associated with the environmental release of transgenic and gene-edited prokaryotes that prevents their practical deployment, and limits the potential of synthetic biology as a whole.

Maxed OOT maxicells are a chassis that is safe for environmental release. Maxicells are achromosomal, non-replicating cells and therefore cannot accumulate mutations over successive generations. Further to their natural properties, we have enhanced their biosafety by putting a block on dangerous horizontal gene transfer - attenuating both of the main risks associated with the environmental release of a transgenic/ gene-edited prokaryote.

For synthetic biology to make the world a better place, synthetic biology itself must first become better. Our novel chassis will breath new life into old iGEM and synthetic biology projects.

Applications of Maxed OOT Maxicells

Biosensors

Maxed OOT maxicells have the unique ability to house organisationally and structurally sophisticated mechanisms whilst preventing HGT, this can be used to create biosensors for use outside the lab. They provide new options in designing mechanisms to sense and report pollutants in drinking or groundwater or particular pathogens in food, patient samples or the environment [2][3].

Bioremediation

Because of the complexity of activity afforded by maxicells a system could be created to remove arsenic from a body of water with cysteine rich proteins [4] then the maxicells would produce gas vesicles to float to surface of water [5] to be skimmed off the top.

Another possibility would be for Maxed OOT maxicells to house the enzymes and/or metabolites needed for a reaction which turns a harmful chemical into a harmless one. These enzymes and metabolites can be protected from inhibitory conditions by being in the maxicell.

Agriculture

Maxicells could be used to create a signal to recruit and help set up an appropriate niche for a healthy rhizosphere around crop roots. They may have use as a spray to house pesticide mechanisms, the new and wider options granted by maxed OOT maxicells over cell free systems may allow design of a safer/more effective pesticide.

Drug Delivery

Specific adherence proteins and surface markers on the maxicells may be used to target a specific cell type/body tissue and release the maxicells drug payload upon arrival. [6] This would decrease severity of side effects such as toxixity and allow a far lesser dosage of the drug to be administered.

Why we don’t Release GMOs

Introduction of a modified or “new” organism onto an environment may have unforeseen impacts on the ecology of the environment it’s being introduced to. Also, horizontal gene transfer from GMO to wild cells has the potential grant wild cells the advantages we’ve given the GMOs which again could cause disruption to ecological balance. These 2 inherent flaws are arguably the major cause of skepticism and fear amongst the many in public and this political discussion surrounding GMOs.

What have we done?

We wanted to make maxicells into as much of a perfect chassis for environmental release as possible and to broaden its potential applications. First we explored the merits of 3 of the most promising maxicell making protocols. Next we worked to characterise maxicells metabolic properties to allow users of the chassis to understand what it can be used for and make designing applications for the chassis easier. Lastly we made maxicells safe for use in the environment by creating our triple lock system which prevents wild cells using maxicell DNA.

Proof of Concept and Fully Realised Chassis

By modeling our colicin kill switch, proving that recoding of a resistance gene is enough to stop it being used by non Maxed OOT cells and creating a plasmid with a resistance for triclosan instead of an antibiotic we have all the parts for proving the concept of out triple lock. Future work would be to assemble all these parts together to have a fully realized triple lock in maxicell making it “Maxed OOT”.

Real world Functionality

Our project was to create this chassis, to make it safe for use in the environment and to make it easy to work with and design for. It’s real potential will be unlocked when future teams take it and improve the world with it. Maxed OOT maxicells are the beginning not the end.

References

1. Zemella, A., Thoring, L., Hoffmeister, C., & Kubick, S. (2015). Cell-Free Protein Synthesis: Pros and Cons of Prokaryotic and Eukaryotic Systems. Chembiochem, 16(17), 2420–2431. http://doi.org/10.1002/cbic.201500340
2. Ahmed, A., Rushworth, J. V., Hirst, N. A., & Millner, P. A. (2014). Biosensors for Whole-Cell Bacterial Detection. Clinical Microbiology Reviews, 27(3), 631–646. http://doi.org/10.1128/CMR.00120-13
3. Hardeep Kaur, Rabindra Kumar, J. Nagendra Babu, SunilMittal (2015) Advances in arsenic biosensor development – A comprehensive review Biosensors and Bioelectronics, 63, 533-545. https://doi.org/10.1016/j.bios.2014.08.003
4. Hai-nan Zhang, Lina Yang, Jian-ya Ling, Daniel M. Czajkowsky, Jing-Fang Wang, Xiao-Wei Zhang, Yi-Ming Zhou, Feng Ge, Ming-kun Yang, Qian Xiong, Shu-Juan Guo, Huang-Ying Le, Song-Fang Wu, Wei Yan, Bingya Liu, Heng Zhu, Zhu Chen, and Sheng-ce Tao (2015).Systematic identification of arsenic-binding proteins reveals that hexokinase-2 is inhibited by arsenic National Academy of Sciences, vol. 112 no. 49 15084-15089. https://doi.org/10.1073/pnas.1521316112
5. Tashiro, Y., Monson, R. E., Ramsay, J. P., & Salmond, G. P. C. (2016).Molecular genetic and physical analysis of gas vesicles in buoyant enterobacteria. Environmental Microbiology, 18(4), 1264–1276. http://doi.org/10.1111/1462-2920.13203

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