Description

Escherichia coli is commonly used as a host for protein expression, as it provides the simplest system to use and a wide choice in expression systems. However, expression of foreign proteins in E. coli often results in various problems with the expressed proteins such as formation of inclusion bodies and degradation by protease. These issues often occur as a result of improper folding of the expressed proteins, and are frequently encountered in protein function research.
It is known that molecular chaperones are involved in the protein folding process, and numerous studies have been conducted to elucidate the mechanisms of in vivo protein folding.
This set contains five types of plasmids developed by HSP Research Institute, Inc., each of which is designed to enable efficient expression of multiple molecular chaperones that are known to work in cooperation as a ”chaperone team” for the protein folding process. It has been reported that coexpression of a target protein with one of these chaperone teams increases recovery of proteins in the soluble fraction; these proteins are often unrecoverable with conventional methods, due to the formation of inclusion bodies (see Figure 1).


Figure 1 Possible model for chaperone-assisted protein folding in E. coli

Storage

–20°C

Available E. coli expression systems

1.

These chaperone plasmids carry an origin of replication derived from pACYC and a chloramphenicol resistance gene (Cmr gene); this allows to use with E. coli expression systems utilizing ColE1-type plasmids with ampicillin resistance gene as a marker, which are the most commonly used. This system cannot be used in combination with chloramphenicol-resistant E. coli host strains or expression plasmids that carry the chloramphenicol-resistant gene. For example, E. coli BL21(DE3), which is often used with pET systems etc., is acceptable as a host strain, but E. coli BL21(DE3) pLysS and BL21(DE3) pLysE, which contain the pLysS or pLysE plasmids that have the pACYC replication origin and the Cmr gene, cannot be used with this system.

2.

This product employs the two step method to construct a system of co-expression of target protein and chaperone. The 1st step is to prepare E. coli host transformed with only chaperone plasmid. The 2nd step is to transform with plasmid which expresses target protein. Therefore, a customer needs to prepare competent cells from the transformant with chaperone plasmid.

Set components

1.	Plasmid pG-KJE8 (10 ng/µl)	100 µl
2.	Plasmid pGro7 (10 ng/µl)	100 µl
3.	Plasmid pKJE7 (10 ng/µl)	100 µl
4.	Plasmid pGTf2 (10 ng/µl)	100 µl
5.	Plasmid pTf16 (10 ng/µl)	100 µl

No.	Plasmid	Chaperone	Promoter	Inducer	Resistant Marker	References
1	pG-KJE8	dnaK-dnaJ-grpE groES-groEL	araB Pzt1	L-Arabinose Tetracyclin	Cm	2 , 3
2	pGro7	groES-groEL	araB	L-araBinose	Cm	2
3	pKJE7	dnaK-dnaJ-grpE	araB	L-Arabinose	Cm	2
4	pG-Tf2	groES-groEL-tig	Pzt1	Tetracyclin	Cm	3
5	pTf16	tig	araB	L-Arabinose	Cm	3

Figure 2 Chaperone plasmids

Notice

The intellectual property of the plasmids supplied in this product is owned by TAKARA BIO INC. This product is intended for research purposes only. Use of this product for commercial purposes such as screening or production requires a separate commercial contract with TAKARA BIO INC. The sequence information on the plasmids supplied in this set are not disclosed, and it is prohibited to modify this product or to use this product for plasmid preparation without prior premmission of TAKARA BIO INC.