Difference between revisions of "Part:BBa K2455003"

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Cell-Penetrating USER Cassette

This biobrick contains an AsiSI/Nb.BSMI USER Cassette with a N-terminal nona-arginine (R9) Cell-penetrating peptide which gives proteins inserted into the cassette the ability to pass through plasma membranes. In addition the USER Cassette carries a N-terminal hexa-histidine tag which allows for easy purification.

For our study we demonstrated that proteins inserted into the cassette can be purified, using the histidine-tag, and subsequently transferred into E. coli cells through the use of the R9 peptide.

In addition; previous studies have shown proteins associated with R9, either covalently or non-covalently, to be able to enter a variety of cell types (Chang et al.).

Insertion Requirements

For insertion of genes into the USER Cassette genes have to be amplified with the primers carrying the two following overhangs:

Forward primer: CGTGCGAUCx

Reverse primer: CACGCGAUxx

Where U = Uracil and x = arbitrary nucleotide; these are needed to keep the inserted gene in-frame.

AsiSI and Nb.BsmI have to be used to facilitate opening of the cassette.

Sequence and Features

Usage and Biology

Cell-Penetrating Peptides (CPPs) are small peptides, typically rich in basic residues, which are able to facilitate transport of a wide variety of cargoes across plasma membranes. Their origin in nature comes from viral domains such as the viral HIV tat domain (Eudes & Chugh, 2008). In recent years research have been done into making synthetic CPPs, especially peptides constructed solely from arginine residues have been of interest. The arginine rich sequence has been shown to trigger endocytosis in a wide range of cell types, including onion and potato cells (Chang et al.).

USER Cassette

The biobrick carries the AsiSI/Nb.BsmI USER Cassette which facilitates gene insertion through the use of USER cloning.

Figure 1: Insertion of genes using USER cloning.Gene constructs consisting of multiple pieces can be inserted through the creation of a series of pieces with matching overhangs. One such use could be to insert point mutations into the gene of choice. The outer most overhangs must match the USER Cassette for the insertion to work.

For more information on USER cloning see [http://www.cbs.dtu.dk/services/AMUSER/ Amuser] or [http://www.cbs.dtu.dk/services/AMUSER/instructions.php Amuser instructions].

Gene Insertion

In order to test the ability of the biobrick to facilitate protein import in E. coli we choose to insert two different fluorescent proteins into it, SYFP2 and mTag BFP.

Opening of USER Cassette

To facilitate insertion we first had to prepare the vector, this was done in a two step digestion reaction. First to open the cassette 42 µL purified vector was mixed with 2.5 µL AsiSI, 10 µL 10x Tango Buffer, and 45.5 µL Nuclease-free water. The mixture was then incubated for 3 hours at 37 degrees Celsius. 5 µL linearised vector was run for 20 min at 100 V on a 1 % Agarose gel to check for proper linearisation.

Billede af CPP digestion

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Evt. oven over column purification og Nb.BSMI digestion

Insertion of BFP and YFP

Smid amplification af gener samt digest/pcr af insert ind.

Cultivation, Purification and SDS-PAGE

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Imaging

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