Dr Neil Dixon


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Production of complex biologics: Host capacity analysis and capability engineering

This project will utilise next generation synthetic biology regulatory tools, to enhance the production and secretion of complex multimeric protein-based biologics from bacterial hosts. RNA-based regulatory tools (riboswitches) have been developed that control gene expression at the level of translation initiation [1-3]. Previously we have used these tools to match our biotechnological demand to host cell synthetic capacity, for example matching expression rates to secretion capacity and inner membrane protein biogenesis allowing enhanced periplasmic secretion and production of recombinant inner membrane protein [4]. This PhD project will seek to co-express and secrete commercially and clinically important multimeric protein-based biologics, such as F(abs), F(ab’)2, and T-cell receptors. This project will provide training in cutting-edge biotechnology, namely synthetic biology enabled host engineering, stress response engineering, and bio-processing engineering important for future careers in both academic and industrial R&D.

[1] Dixon et al 2010 Reengineering orthogonally selective riboswitches Proc Natl Acad Sci USA. p 2830 
[2] Dixon et al 2012 Orthogonal riboswitches for tuneable coexpression in bacteria. Angew Chem Int Ed Engl. p3620 
[3] Morra et al 2016 Dual transcriptional-translational cascade permits cellular level tuneable expression control. 
Nucleic Acids Res. e21 
[4] Morra et al 2017 Optimization of Membrane Protein Production Using Titratable Strains of E. coli. Methods Mol Biol. p83

Dynamic Ribo-regulator Tools for Expression Control in Mammalian Cells

The development of novel SynBio gene expression tools offers the potential to refine expression and co-expression of both native host and recombinant proteins [1]. Ribo-regulation offers an attractive alternative means of control gene expression by control translation, stability and/or processing of mRNA [2]. The ability to finely regulate expression in mammalian has many biotechnological application and huge potential biological and biomedical impact. These range from producing recombinant therapeutic proteins to engineering cellular safety switches for cell therapy applications [3]. However such tools to permit fine tuned regulation in mammalian cells are currently limited. The series of inducible systems used in mammalian cell systems are restricted to transcriptional control sites and are relatively coarse in their control parameters [4]. For example, as post-transcriptional events are known to restrict the expression and processing of commercially-valuable secreted biopharmaceuticals [5], the ability to develop fine tuned control of post-transcriptional events offers wide scope for more efficient production processes. Uniquely, a combination of transcriptional and Ribo-regulation offers the opportunity to develop combinatorial, multiplexed regulation of cellular events (e.g. mRNA production, specific mRNA ribosomal engagement, secretory vesicular transit, precursor availability – and multiples thereof) to maximise the effectiveness of the host cell platform as a “factory” for desired protein manufacture. 

 This PhD project will seek to enhance the production of protein-based biotherapeutics, to lower manufacturing costs of these important medicines and reduce the burden upon the NHS and other national healthcare providers. This will entail the use of ribo-regulators and synthetic biology methods (Dixon), and mammalian cell (Chinese Hamster Ovary, CHO, and HEK) culture and bioprocess optimisation (Dickson). The driver of this applied research is to provide enhanced production processes and training to support the knowledge-based bio economy (KBBE). This PhD project will provide training in state of the art synthetic/molecular biology techniques, advanced analytical methods, and bioprocess performance analysis.

[1] Neil Dixon, et al. Orthogonal Riboswitches for Tuneable Co-expression in Bacteria. Angewandte Chemie International Edition (2012)

 [2] Rosa Morra, Jayendra Shankar, Neil Dixon et alDual transcriptional-translational cascade permits cellular level tuneable expression control. Nucleic Acids Research (2016)

[3] Di Stasi A, et al. Inducible apoptosis as a safety switch for adoptive cell therapy N Engl J Med. (2011)

[4] Misaghi, S, et al (2014) It’s time to regulate: Coping with product-induced non-genetic clonal instability in CHO cell lines via regulated protein expression. Biotechnol. Prog. 30: 1432-1440.

[5] Hussain, H et al (2014) The endoplasmic reticulum and unfolded protein response in the control of mammalian recombinant protein expression Biotechnol. Lett. 36: 1581-1593. 

For further details please contact Neil Dixon or Alan Dickson

PhD opportunities