Part:BBa_K2918019
WT T7 promoter - Universal RBS - Φ29 TP - T7 terminator
A level 1 MoClo construct with a Wild-type T7 promoter, a universal RBS, phi29 TP and a T7 terminator
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12INCOMPATIBLE WITH RFC[12]Illegal NheI site found at 237
- 21INCOMPATIBLE WITH RFC[21]Illegal BamHI site found at 557
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
The construct is confirmed by sequencing and there are no mutations.
Usage and Biology
The Φ29 replication mechanism involves replication of a protein-primed based replication linear DNA. Protein primed replication, unlike the conventional DNA or RNA primed mechanism, do not depend on specific sequences of DNA/RNA and simplifies the design of replication systems. The Φ29 replication can be established by using four simple proteins: Φ29 DNA polymerase ( (DNAP/p2), terminal protein (TP/p3), single stranded binding protein (SSB/p5) and double stranded binding protein (DSB/p6). The replication process begins by binding of the Φ29 DNA polymerase and terminal protein complex at the origins of replication (OriL and OriR), which flank the protein-primed linear plasmid (Salas et al., 1994). The double stranded DNA binding proteins (DSB/p6) aid in the process of replication and bind more intensely at the origins of replication (OriL and OriR), destabilizing the region and facilitating strand displacement. Single stranded binding proteins bind to the displaced DNA strand, preventing strand switching of the DNA polymerase and protecting the linear plasmid from host nucleases (Salas et al., 1994). The replication mechanism is depicted in Figure 1. If you want to read more about this mechanism, you can take a look at our Design page!
The Φ29 replication system is promising in many ways:
- The Φ29 DNA polymerase has the highest processivity of all known single subunit DNA polymerases (Blanco et al., 1988), and can be used for whole genome amplification.
- The Φ29 machinery along with cell free expression systems can be used to establish the three dogmas of biology in vitro, setting the basis for artificial cell development.
- The existing DNA-protein covalent bonds offer many possibilities to engineer the terminal proteins with functional peptide sequences.
- We envision that the unique configuration of the double-stranded, protein-capped linear replicon will be a basis for many new engineered protein-DNA complexes.
- Orthogonal replication not only enables replication independent from the host, but the ability to engineer the orthogonal DNA polymerase’s fidelity without introducing mutations in the cell’s genome makes in vivo directed evolution a possibility.
Toxicity
Our Sci-Phi 29 tool is based on four components of the Φ29 bacteriophage: DNAP, TP, p5 and p6. However, overexpression of these proteins are toxic for the cell. In order to determine the optimal expression levels of the proteins in live cells, we carried out viability assays in E. coli BL21(DE3) pLysS. The results are shown in the graphs below.
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