Cell-Free Transcription and Translation Tether Expressed Peptides to Their Encoding Circular DNA.

Area of Science:

• Biotechnology
• Molecular Biology
• Synthetic Biology

Background:

• Cell-free protein display technologies are crucial for molecular evolution and screening.
• Existing methods like CIS display have limitations, including dependence on specific replication machinery.

Purpose of the Study:

• To introduce and characterize a novel cell-free display technology called ICED (Intra-Circular Expression and Display).
• To demonstrate ICED's efficiency and mechanistic basis for protein display on circular DNA.

Main Methods:

• Developed ICED technology for displaying proteins on their encoding circular DNA.
• Utilized affinity-based screening and reconstituted E. coli replication-cycle reaction (RCR) for enrichment.
• Investigated the linkage mechanism through DNA linearization, transcription termination, and enzymatic treatments.

Main Results:

• ICED effectively displays proteins on circular DNA without requiring specific replication initiators or cis-acting elements.
• The display is dependent on an intact transcription-translation (TX-TL) complex, indicating a novel linkage mechanism.
• Achieved 10^8-fold enrichment in two rounds by reusing RCR products, surpassing conventional platforms.

Conclusions:

• ICED offers a more efficient and straightforward cell-free display platform.
• The findings provide new insights into the mechanistic interface of transcription-translation (TX-TL) coupling.
• ICED is compatible with both crude cell extracts and reconstituted systems like PURE.