"
Team:Bordeaux/Parts/BBa K1317002
From 2014.igem.org
m |
m |
||
| Line 8: | Line 8: | ||
<p> | <p> | ||
| - | We tried to assemble the gene coding for the SLPs from 8 oligonucleotids with | + | We tried to assemble the gene coding for the SLPs from 8 oligonucleotids with homologous regions with the Gibson Assembly. The oligos were designed with the software DNA Works (Helix Systems) <br> |
First of all, consensus sequences for the spider silk were identified and our own protein was designed. Then, the nucleotidic sequence using the peptidic sequence was determined. We had to pay attention because our proteic sequence is made of repeted motifs.<br><br> | First of all, consensus sequences for the spider silk were identified and our own protein was designed. Then, the nucleotidic sequence using the peptidic sequence was determined. We had to pay attention because our proteic sequence is made of repeted motifs.<br><br> | ||
</p> | </p> | ||
| Line 19: | Line 19: | ||
Figure 1: Strategy of the Gibson Assembly to assemble the gene coding for the SLPs<br><br><i></center> | Figure 1: Strategy of the Gibson Assembly to assemble the gene coding for the SLPs<br><br><i></center> | ||
<p> | <p> | ||
| - | Our 8 oligo weren’t assembled with these 2 methods, so another method was used : the PCR- | + | Our 8 oligo weren’t assembled with these 2 methods, so another method was used : the PCR-Fusion.<br> |
This method is made of different steps using the Phusion® High Fidelity Polymerase (picture 2). In a first step fragments were joining two by two, then fragments 1-2 were joined to fragments 3-4 and a PCR is achieved using fragments 1 and 4 as primers. The same method was used for fragments 5-6 and 7-8.<br> | This method is made of different steps using the Phusion® High Fidelity Polymerase (picture 2). In a first step fragments were joining two by two, then fragments 1-2 were joined to fragments 3-4 and a PCR is achieved using fragments 1 and 4 as primers. The same method was used for fragments 5-6 and 7-8.<br> | ||
Finally, fragments 1-2-3-4 were assembled to fragments 5-6-7-8 and a PCR was also achieved using the fragments 1 and 8 as primers.<br><br></p> | Finally, fragments 1-2-3-4 were assembled to fragments 5-6-7-8 and a PCR was also achieved using the fragments 1 and 8 as primers.<br><br></p> | ||
Revision as of 17:15, 17 October 2014
Link to the registry of Standard Parts: [http://parts.igem.org/Part:BBa_K1317002 http://parts.igem.org/Part:BBa_K1317002]
Initial strategy :
We tried to assemble the gene coding for the SLPs from 8 oligonucleotids with homologous regions with the Gibson Assembly. The oligos were designed with the software DNA Works (Helix Systems)
First of all, consensus sequences for the spider silk were identified and our own protein was designed. Then, the nucleotidic sequence using the peptidic sequence was determined. We had to pay attention because our proteic sequence is made of repeted motifs.
Table 1 : sequences of the 8 nucleotides
2 different methods were used with the Gibson Assembly1: in one step at 50°C or with cycles of denaturation at 95°C and annealing at 50°C (figure 1). The enzyme used was the Phusion® High Fidelity Polymerase.
Figure 1: Strategy of the Gibson Assembly to assemble the gene coding for the SLPs
Our 8 oligo weren’t assembled with these 2 methods, so another method was used : the PCR-Fusion.
This method is made of different steps using the Phusion® High Fidelity Polymerase (picture 2). In a first step fragments were joining two by two, then fragments 1-2 were joined to fragments 3-4 and a PCR is achieved using fragments 1 and 4 as primers. The same method was used for fragments 5-6 and 7-8.
Finally, fragments 1-2-3-4 were assembled to fragments 5-6-7-8 and a PCR was also achieved using the fragments 1 and 8 as primers.
Figure 2: PCR Fusion strategy to assemble the gene coding for the SLPs
This method wasn’t successful because fragments 6 and 7 were unable to join. Therefore, new fragments were designed with a different homolog region. The fragment 8 that added only 2 nucleotids was suppressed and these 2 nucleotids were added on fragments 7.
Table 2: Sequence of the new fragments
Then, a new strategy was used (picture 3). The two first steps are common but then, fragments 5-6 are joined to fragments 1-2-3-4 and the PCR is made with the fragments 1 and 6. Finally the fragment 7 is added and a PCR is also achieved.
Fig 3 : Strategy to assemble the CDS for the SLPs using the new fragments 6 and 7
This method enable the assembly of the 7 fragments (picture 4). A fragment of 318 bp was expected on the electrophoresis gel.
Figure 4 : Gel electrophoresis on 3% agarose
Reference :
[1] https://www.neb.com/tools-and-resources/feature-articles/gibson-assembly-building-a-synthetic-biology-toolset
[2] Shevchuk N.A., Bryksin A.V., Nusinovich Y.A., Cabello F.C., Sutherland M. et Ladisch S. Construction of long DNA molecules using long PCR-based fusion of several fragments simultaneously (2004) Nucleic Acids Res., 32(2), 19
