Biomod/2011/TeamJapan/Tokyo/Project/Model of the light irradiated gathering mode
Light-irradiated gathering mode
- 5' -(NH2)-TTTTTT TTTTCACTATTTCGACCGGCTCGGAGAAGAG TTTTT CT X CT X TC-3' (X means azobenzene. )
- Size: 48bases + 2azobenzenes
- UV-switching DNA is used for the scaffold in light-irradiated gathering mode. We designed this DNA by ourselves. UV-switching DNA has a five bases’ loop (TTTTT) and there are two azobenzenes (X) in the one side of the stem (CTXCTXCT).
- By spotting UV, azobenzenes are isomerized (trans to cis), so the part which contains azobenzenes becomes hard to form double strand. It is known that UV-switching can be realized by using this principle. (ref)
- To achieve this switching, it is necessary to design the stem which forms the loop firmly in the room temperature and opens the loop by isomerizing of two azobenzenes. We didn’t find the precedent which succeeded in opening and closing at a single molecular by azobenzenes which are inserted into a stem, so the designing is very difficult. After trial and error, we designed to use “GAAGAG” and “CTXCTXCT” as the stem and “TTTTT” as the loop.
- The 7th to 37th bases from 5' end (TTTTCACTATTTCGACCGGCTCGGAGAAGAG) is a complete complementary part for the deoxyribozyme. In addition, the 7th to 31th bases from 5’ end (TTTTCACTATTTCGACCGGCTCGGA) are a complementary part for blocking DNA. Consequently, the 32th to 37th bases from 5’ end (GAAGAG) are a complementary part for deoxyriboyme and not a complementary part for blocking DNA, so branch migration is started from this part and blocking DNA is released. Moreover, these 6 bases are a part which makes stem, so this part is blocked when the loop is closed. By this structure, branch migration doesn’t happen when the loop is formed.
- We designed the first 6 bases from 5' end as a linker (TTTTTT). This is also designed not to make unexpected structures. As a result, we decide using this linker.
- The 5' end is aminated to be fixed on a glass plate.