Expression system
View Patent ↗A protein expression system is provided. The system comprises: a) a T7 RNA polymerase-dependent promoter operably linked to an expression cassette for a protein of interest; and b) an expression cassette for T7 RNA polymerase operably linked to a λpL promoter and at least two perfect palindrome operator sequences.
1. A protein expression system comprising:
a) a T7 RNA polymerase-dependent promoter operably linked to an expression cassette for a protein of interest; and
b) an expression cassette for T7 RNA polymerase operably linked to a λpL promoter and at least two perfect palindrome operator sequences.
2. An expression system according to claim 1 , wherein the perfect palindrome operator sequences are selected from the group consisting of lac, gal, deo and gln.
3. An expression system according to claim 1 or 2 , wherein dual perfect palindrome operator sequences are employed.
4. An expression system according to claim 1 , wherein the T7 RNA polymerase-dependent promoter and the expression cassette for T7 RNA polymerase are located on plasmids.
5. An expression system according to claim 4 , wherein the T7 RNA polymerase-dependent promoter and the expression cassette for T7 RNA polymerase are located on separate compatible plasmids.
6. A method for the production of a protein which comprises expressing an expression system according to claim 1 .
7. A method according to claim 6 , wherein the expression occurs in an E. coli host cell.
8. A plasmid comprising an expression cassette for T7 RNA-polymerase operably linked to a λpL promoter and at least two perfect palindrome operator sequences.
9. A host cell transformed with a plasmid according to claim 8 .
10. A host cell according to claim 9 , wherein the host is E. coli.
11. A host cell according to claim 10 , wherein the host is E. coli strain B or strain K12.
12. An expression system according to claim 4 , wherein the perfect palindrome operator sequences are selected from the group consisting of lac, gal, deo and gln.
13. An expression system according to claim 12 , wherein dual perfect palindrome operator sequences are employed.
14. The method of claim 7 , wherein the E. coli host cell is a B strain.
15. The method of claim 7 , wherein the E. coli host cell is a K12 strain.