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From 2011.igem.org

Promoter Library

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Aims:

The aims of creating a promoter/RBS library are:

- To create a new tool set for controlling gene expression levels in a modular pathway
- To increase the efficiency of construct production by reducing the total number of ligations to be performed

Methods:

A Stock of Promoters and RBS

1. Transform Top 10 with DNA from the kit plate.

The following Promoters were chosen:
Strong Promoter (BBa_J23119)
Weak Promoter (BBa_J23106)
pBAD Promoter (BBa_K206000)
Bluf Promoter (BBa_K238013)
OmpC Promoter (BBa_R0082)
OmpF Promoter (BBa_R0084)

The following Ribosome Binding Sites were chosen:

Strong RBS (BBa_B0034)
Weak RBS (BBa_J61101)

2. Overnight the successful colonies
3. Miniprep the overnights

A Stock of Constructs of Promoters with RBS

We aimed to make the following constructs:

Strong Promoter + Strong RBS
Strong Promoter + Weak RBS
Weak Promoter + Strong RBS
Weak Promoter + Weak RBS
pBAD Promoter + Strong RBS
pBAD Promoter + Weak RBS
Bluf Promoter + Strong RBS
Bluf Promoter + Weak RBS
OmpC Promoter + Strong RBS
OmpC Promoter + Weak RBS

The AlwnI Method
Both Ribosome Binding Sites that we worked with are only 12 base pairs long, making them impossible to visalise on an agarose gel.
This is a common problem when ligating small Biobrick parts together. For this reason we had to come up with a novel method of ligating these small constructs. This method, the ''AlwnI'' method, uses the restriction enzyme "AlwnI" to cut plasmids in a site which is commonly found in origins of replication. It is detailed below.

1. Digest the plasmid containing the promoter with AlwnI and SpeI.
2. Digest the plasmid containing the ribosome binding site with AlwnI and XbaI.
3. Run the samples on a gel.
4. Perform a gel extraction. Ensure you know the size of the fragments you are keeping.
5. Ligate the promoter fragment to the RBS fragment.
6. Transform the ligation into E.coli. Overnight and miniprep colonies.



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