Coexpression
of caiB and caiE with Two Plasmids in E.coli
FAN Li-Qiang, YUAN Qin-Sheng*
( Institute of Biochemistry, East China University of Science and
Technology, Shanghai 200237, China )
WU Xiang-Fu*
( Shanghai Institute of Biochemistry, the Chinese Academy of Sciences,
Shanghai 200031, China )
Abstract Recombinant
bacteria exhibiting high enzymatic activities were obtained by cloning and
coexpression of both caiB gene and caiE gene in the host of E.coli
Bl21(DE3), which encode carnitine dehydratase and a protein related to the
synthesis of cofactor for carnitine dehydratase, respectively. In order to
coexpress these two genes, compatible and incompatible two plasmids system were
used, the difference between them was also studided. After induction with IPTG,
both caiB and caiE genes were coexpressed in both compatible two
plasmids system and incompatible two plasmids system. In the former system, the
expressed products accounted for 17% and 10% of the total proteins in the host;
in the later system, the proportion was 39% and 20%, receptively. The activity
of carnitine dehydratase in E.coli Bl21(DE3) with either coexpression
system is about 2.3 times than that in E.coli Bl21(DE3) with only pET28-caiB.
The plasmids stabilities in these two systems were the same, all needed the
help of antibiotic selective pressure.
Key words carnitine; coexpression; two plasmids; compatible
plasmids; incompatible plasmids
*Corresporing author: YUAN
Qin-Sheng: Tel, 86-21-64252255; e-mail, [email protected].
WU Xiang-Fu: Tel, 86-21-64374430-5292; e-mail, [email protected]