Difference between revisions of "Part:BBa K4765025"

Revision as of 13:48, 12 October 2023

Rv Dsup codon optimized

Introduction

Rv Dsup is a damage suppressor protein from the Tardigrade Species Ramazzottius Varieornatus ^[1] . This is a nucleosome-binding protein that protects chromatin from hydroxyl radicals^[2] , thereby inhibiting DNA molecule breakage. This protein can reduce X-ray-induced damage in human cells by 40%.

Usage and Biology

We optimized the codons of wildtype Rv Dsup for E. coli K12 and heterologously expressed it in E. coli to enhance its survival rate under UV radiation.

Characterization

Sequencing map

Figure 1. Sequencing map of Rv Dsup Sequencing starts from the T7 terminator, with the primer 5-GCTAGTTATTGCTCAGCGG-3.

Successful Protein Expression

Figure 3. SDS-PAGE electrophoresis of Rv Dsup We constructed Rv Dsup into the pET28a plasmid and transformed it into E. coli BL21 DE3. Lanes 1 to 2 represent Rv Dsup, Rv Dsup + IPTG, as indicated by the red arrow, we successfully expressed Rv Dsup.

Anti-UV Survival Assay

We employed the Colony-Forming Unit (CFU) assay. After plasmid transformation and plating, we shielded one/half of the agar plate from UV light using a black cloth, while the other one/half was exposed to UV irradiation (6W power) with wavelengths of 254 nm and 365 nm for 10 seconds.

Figure 2. Anti-UV Assay.

Our experimental results revealed that the majority of DNA repair and binding proteins exhibited significantly increased survival rates when compared to plain E. coli, indicating enhanced resistance to UV radiation, with XRCC1 and FEN1 being particularly noteworthy. Although E. coli expressing Dsup showed a slightly higher survival rate, this difference wasn't statistically significant. We hypothesized that these proteins operate by facilitating DNA repair or binding to DNA, thereby shielding chromatin from hydroxyl radicals induced by UV radiation.

Interestingly, we observed that the expression of green fluorescence **(stayGold)** in *E. coli*, intended as a negative control, significantly enhanced the survival rate. We suspected that this effect may be due to fluorescent protein absorbing a certain amount of UV radiation through structural changes.

Figure 3. Plates displaying transformed E. coli after anti-UV assay.

Figure 4. Survival Rate after UV Exposure. Percentage of viable E. coli expressing proteins following UV radiation exposure (Note: The quantitative graph is based on the whole plate CFU to avoid the blurriness at the boundaries of the cloth-shielded area from UV.)

Sequence and Features

Reference

1. ↑ Hashimoto, T., Horikawa, D. D., Saito, Y., Kuwahara, H., Kozuka-Hata, H., Shin-I, T., Minakuchi, Y., Ohishi, K., Motoyama, A., Aizu, T., Enomoto, A., Kondo, K., Tanaka, S., Hara, Y., Koshikawa, S., Sagara, H., Miura, T., Yokobori, S. I., Miyagawa, K., Suzuki, Y., … Kunieda, T. (2016). Extremotolerant tardigrade genome and improved radiotolerance of human cultured cells by tardigrade-unique protein. Nature communications, 7, 12808. https://doi.org/10.1038/ncomms12808
2. ↑ Chavez, C., Cruz-Becerra, G., Fei, J., Kassavetis, G. A., & Kadonaga, J. T. (2019). The tardigrade damage suppressor protein binds to nucleosomes and protects DNA from hydroxyl radicals. eLife, 8, e47682. https://doi.org/10.7554/eLife.47682