Difference between revisions of "Part:BBa K4158012"

Latest revision as of 02:01, 11 October 2022

SRTF1(E coli Codon Optimized sequence)

This part contains RBS and SRTF1-SSGSSG-TEV-His coding site. SRTF1 is a bacterial(steroid metabolizing bacterium; Pimelobacter simplex) transcription factor.

SRTF1 sequence is optimized to E. coli codon. This part is the improvement of BBa_K3889021(B. sub optimized SRTF1).

Fig. 1. progesterone detector gene circuit

Design SRTF1 amino acid sequence was cited from a previous paper[1].

We designed this part by

• optimizing SRTF1 amino sequences to E.coli codon by using GeneArt(Thermo).
• optimizing the 5'UTR by using RBS calculator and RNA fold.

Then, we inserted the fragment into pET26b(+) vector.

Results

In order to detect progesterone in vitro, we transformed this part into BL21(DE3)Star strain and prepared crude extracts which were pre-enriched with the transcription factor, SRTF1.

Fig. 2. Preparation of SRTF1-enriched extract

We also prepared cell-free extract enriched with the B. subtilis optimized SRTF1, using BBa_K3889021. Then, we performed SDS-PAGE to compare the expression of the protein in E. coli with both of the parts.

From Fig. 3., we could confirm that SRTF1(22kDa) codon-optimized for E.coli was successfully expressed in E. coli. On the other hand, the molecular mass of the protein optimized for Bacillus subtiliswas smaller than that of SRTF1 (22kDa). Thus, we found that SRTF1 gene optimized for Bacillus subtilis was not fully translated inE.coli due to the difference in codon usage in these two organisms.

Fig. 3. The result of SDS-PAGE (SRTF1)

We also performed cell-free protein synthesis reaction with the extracts, using BBa_K4158010 as the reporter plasmid. Fig. 4. shows the result of the experiment. We added 100uM of progesterone in the final concentration. We demonstrated that this part could detect progesterone in the cell-free protein synthesis system.

Fig. 4. comparison of result of progesterone sensing by SRTF1

We could confirm below from Fig. 4..

• The plain(BBa_K4158012): there is a significant difference of the fluorescence between progeterone added and not added.
• The shaded(BBa_K3889021): there isn't a significant difference of the fluorescence between progeterone added and not added..

Thus, we succeeded in engineering SRTF1-expressing plasmid which works in E.coli, as a part improvement of BBa_K3889021.

Sequence and Features

References

1. Sankar K et al. A progesterone biosensor derived from microbial screening. ACS Sens. 7(4):1132-1137(2022).