Dynamic protocellular systems
Previous and Current Research
One of the grand challenges within synthetic biology is the design and construction of synthetic microsystems which mimic basic properties of natural cells. Basic biological compartmentalisation is a key property of artificial cells and existing solutions are found in self-assembled amphiphiles, polymers, inorganic molecules and protein-surfactant conjugates which form membrane delineated aqueous droplets, however the interior of these compartments are typically homogeneous and therefore do not mimic the crowded heterogeneous cytoplasm of natural cells.
This limitation can be addressed via alternative models based on liquid-liquid phase separation (coacervates) of oppositely charged macromolecules and polymers. The resulting membrane-free synthetic droplets have a chemically enriched interiors which are highly charged and crowded. As a consequence they passively sequester a range of different molecules generating a high local concentration of molecules inside the droplet1. However, low surface tension makes them relatively unstable to coalescence limiting their use in synthetic biology as discrete artificial cellular compartments2. We work across disciplines and use a variety of techniques including microfluidics, standard microscopies (electron, optical, fluorescence, confocal), spectroscopies (fluorescence, UV, CD), scattering techniques (X-ray, light), protein expression and characterization and cell-free gene expression to investigate the utility of coacervate microdroplets as robust reaction compartments and cellular mimics.
Previous work has given insights into the mechanistic pathways leading to small molecule sequestration in membrane-free coacervate protocells; successfully demonstrated the use of liquid-liquid phase separated micro compartments for protein expression using cell free expression systems; exploited microfluidics for the high throughput formation of stable, monodisperse microdroplets; and integrated two contrasting modes of protocell construction to produce a novel hybrid model based on fatty acid membrane-bound coacervate micro-droplets.
We are now focused on developing these systems further by integrating non-equilibrium processes into the design rules for the construction of activated novel protocells. To achieve this, we work between biophysics, materials science and synthetic biology to gain new insights into the physical phenomena which drive out of equilibrium processes in cells and to reimagine and translate these insights into novel, robust and dynamic systems for synthetic biology applications.
1 Koga S, Williams DS, Perriman AW, Mann S: Nature Chemistry 2011, 3:720–724
2 Williams DS, Koga S, Hak CRC, Majrekar A, Patil AJ, Perriman AW, Mann S: Soft Matter 2012, 8:6004–6014.
Future Projects and Goals
- Developing a plug and play tool kit for the construction of artificial cells, organelles and tissues with specific functions including energy conversion and metabolism.
- Creating a synergy between cell biology and synthetic biology to bring new insights into biological phenomena via in-vitro reconstitution.
- Developing new tools for simulating extreme conditions (high pressure) for cell biology and synthetic biology.
- High throughput synthesis of dynamic artificial systems.
Methodological and Technical Expertise
- Protocell models
- High pressure for soft matter
- Cell free expression
- Biophysical characterisation
Tang T-YD, Van Swaay D, de Mello A, Anderson JLR, Mann S
In vitro gene expression within membrane-free coacervate protocells
Chemical Communications, 51, 11429–11432
Van Swaay D , Tang T-YD , Mann S, de Mello A
Microfluidic formation of formation of Membrane-Free Aqueous Coacervate Droplets in Water
Angewandte Chemie, 2015,54, 29, 8398–8401
Li M, Huang X, Tang T-YD, Mann S
Synthetic cellularity based on non-lipid micro-compartments and protocell models
Current Opinion in Chemical Biology, 2014, 22, 1–11
Tang T-YD, Che Hak CR, Thompson AJ, Kuimova MK, Williams DS, Perriman AW, Mann S
Fatty acid membrane assembly on coacervate micro-droplets as a step towards a hybrid protocell model
Nature Chemistry, 2014, 6, 527–533
Tang T-YD, Antognozzi M, Vicary J, Perriman AW, Mann S
Small-molecule uptake in membrane-free peptide/nucleotide protocells
Soft Matter, 2013,9, 7647–7656