Difference between revisions of "Part:BBa K4765016"

Sequencing starts from the T7 terminator, with the primer 5-GCTAGTTATTGCTCAGCGG-3.

We constructed H. ex mtSSB into the pET28a plasmid and transformed it into E. coli BL21 DE3. Lanes 1 to 2 represent H. ex mtSSB, H. ex mtSSB + IPTG, as indicated by the red arrow, we successfully expressed H. ex mtSSB.

Desiccation Survival Assay

We attempt to compare the anti-desiccation capabilities of H. ex mtSSB and the pre-existing protein BBa_K2306003 in order to identify a suitable desiccation-resistant protein for B-HOME. Through the experiments, we found that H. ex mtSSB exhibits desiccation resistance comparable to SAHS.

Figure 3. Workflow of Desiccation Survival Assay

We've designed an experimental group with H. ex mtSSB and SAHS 33020, and used E. coli transformed with the empty PET28 vector as a control. All proteins are expressed via leakage in E. coli BL21 DE3. All the groups are incubated overnight. After reaching an OD value of 1.0, liquid culture is centrifuged, and the supernatant is removed. Pellets are dried for 6.5 hr in SpeedVac (Savant SpeedVac SC100) under 4 0 °C .Finally, the pellets are resuspended in LB medium and dilute 10^5-fold for CFU counting.

Figure 4. Dry weight of H.ex mtSSB, TDP, and control after drying There is no statistically significant difference in the dry weights among the experimental groups, indicating that the number of E. coli is consistent between the bacterial tubes.

Figure 5. CFU colony count of H.ex mtSSB, TDP, and control after drying The E. coli expressing H.ex mtSSB and SAHS showed higher CFU counts after drying compared to the control group, indicating their desiccation resistance abilities. Mean values from three rounds of indepdent experiments are shown. Huge error bars suggest variations between rounds of experiments.

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 6. Anti-UV Assay.

In our experimental findings, while mtSSB effectively guards against DNA damage caused by desiccation through its binding to single-stranded DNA, we did not observe any enhancement in UV resistance in E. coli expressing mtSSB. Surprisingly, the survival rate of E. coli expressing mtSSB was even lower than that of the control group without mtSSB.

Figure 7. Plates displaying transformed E. coli after anti-UV assay.

Figure 8. 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