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OnePot PURE Cell-Free System
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Dissecting limiting factors of the Protein synthesis Using Recombinant Elements (PURE) system
Jun Li1,2, Chi Zhang1, Poyi Huang1
1Department of Genetics, Harvard Medical School, Boston, MA, USA.
Translation (Austin, Tex.)
|July 14, 2017
Summary
The Protein synthesis Using Recombinant Elements (PURE) system offers improved protein synthesis over crude extracts, but yields partially translated proteins. Optimizing substrates like creatine phosphate and magnesium, and using factors like EF-P and ArfA, enhances functional protein production.
Area of Science:
- Biochemistry
- Molecular Biology
- Synthetic Biology
Background:
- Cell-free protein synthesis (CFPS) systems enable high-throughput and controlled in vitro protein production.
- The Protein synthesis Using Recombinant Elements (PURE) system and commercial S30 crude extract systems are common CFPS methods.
- Both systems face challenges with protein yield, activity, and ribosome recycling efficiency, particularly for large proteins.
Purpose of the Study:
- To compare the efficiency and limitations of the PURE system against a commercial S30 crude extract system for in vitro protein synthesis.
- To investigate methods for optimizing the PURE system to improve full-length and functional protein yields.
- To identify factors that mitigate issues like mRNA degradation, partial translation, and ribosome stalling.
Main Methods:
- Comparative analysis of PURE and S30 crude extract systems using firefly luciferase (Fluc) as a model protein.
- Systematic fed-batch analysis of the PURE system with individual and combined replenishment of small molecule substrates.
- Assessment of the impact of elongation factors (EF-P) and ribosome rescue factors (ArfA, YaeJ, PrfH) on protein synthesis.
Main Results:
- The PURE system exhibited less mRNA degradation and produced up to 6-fold more full-length proteins than the S30 system, but with lower overall protein activity.
- Both systems showed low ribosome recycling efficiency for large proteins (82–224 kD).
- Fed-batch optimization of PURE with creatine phosphate and magnesium increased Fluc yield 1.5–2 fold; EF-P increased functional protein fraction; ArfA reduced ribosome stalling and improved productivity.
Conclusions:
- While the PURE system offers advantages in producing full-length proteins, optimization is crucial for enhancing functional yield and overcoming limitations like ribosome stalling.
- Strategic supplementation with specific small molecules (creatine phosphate, magnesium) and translation factors (EF-P, ArfA) can significantly improve CFPS efficiency and protein quality.
- These findings provide a basis for developing more robust and productive cell-free protein synthesis platforms.
