Plasmids and phages for homologous recombination and methods of use
Lambda phages that can be used to introduce recombineering functions into host cells are disclosed. Also disclosed are plasmids that can be used to confer recombineering functions to a variety of strains of E. coli and to other bacteria, including Salmonella, Pseudomonas, Cyanobacteria, Spirochaetes . These plasmids and phages can be isolated in vitro and can be used to transform bacterial cells, such as gram negative bacteria.
1. A plasmid, comprising an origin of replication (ori) selected from the group consisting of pSC101, colE1, pBBR1 and RK2, a nucleic acid encoding a selectable marker, a nucleic acid encoding a promoter operably linked to a nucleic acid sequence encoding a repressor that specifically binds a P L promoter of lambda phage, and a lambda genome comprising the P L promoter of lambda phage operably linked to a nucleic acid encoding Beta, Exo and Gam and a terminator,
wherein the selectable marker replaces the rexAB coding region in the lambda genome, wherein the lambda genome contains an N-kil deletion, and wherein bacterial host cells transformed with the plasmid can perform homologous recombination.
2. The plasmid of claim 1 , wherein the on ori allows replication of the plasmid in Salmonella typhimurium, Escherichia coli , or both.
3. The plasmid of claim 1 , comprising in 5′ to 3′ order
(1) O R ;
(2) a nucleic acid encoding a repressor that binds the P R promoter;
(3) a promoter operably linked to a nucleic acid encoding a heterologous nucleic acid sequence;
(4) O L ;
(5) P L ; and
(6) a nucleic acid encoding Beta.
4. The plasmid of claim 1 , wherein the ori is pSC101.
5. The plasmid of claim 1 , wherein the ori is pBBR1.
6. The plasmid of claim 1 , wherein the ori is RK2.
7. The plasmid of claim 1 , wherein the ori is colE1.
8. The plasmid of claim 1 , wherein the plasmid is pSIM2, pSIM4, pSIM5, pSIM6, pSIM7, pSIM8 or pSIM9.
9. The plasmid of claim 8 , wherein the plasmid is pSIM2.
10. The plasmid of claim 8 , wherein the plasmid is pSIM4.
11. The plasmid of claim 8 , wherein the plasmid is pSIM5.
12. The plasmid of claim 8 , wherein the plasmid is pSIM6.
13. The plasmid of claim 8 , wherein the plasmid is pSIM7.
14. The plasmid of claim 8 , wherein the plasmid is pSIM8.
15. The plasmid of claim 8 , wherein the plasmid is pSIM9.
16. A method of producing a bacterial host cell that can perform homologous recombination, comprising introducing the plasmid of claim 1 into the bacterial host cell, thereby rendering the bacterial cell capable of performing homologous recombination.
17. The method of claim 16 , wherein the host cell is a gram negative bacterial cell.
18. The method of claim 16 , wherein the host cell is an Escherichia coli cell.
19. A plasmid, comprising an origin of replication selected from the group consisting of pSC101, colE1, pBBR1 and RK2, a nucleic acid encoding a selectable marker, a nucleic acid encoding a promoter operably linked to a nucleic acid sequence encoding a repressor that specifically binds a P L promoter of lambda phage, and a lambda genome comprising the P L promoter of lambda phage operably linked to a nucleic acid encoding Beta and a terminator 3′ of the nucleic acid encoding Beta, wherein the plasmid comprises SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6 or SEQ ID NO:7.
20. The plasmid of claim 19 , wherein the plasmid comprises SEQ ID NO: 1.
21. The plasmid of claim 19 , wherein the plasmid comprises SEQ ID NO: 2.
22. The plasmid of claim 19 , wherein the plasmid comprises SEQ ID NO: 3.
23. The plasmid of claim 19 , wherein the plasmid comprises SEQ ID NO: 4.
24. The plasmid of claim 19 , wherein the plasmid comprises SEQ ID NO: 5.
25. The plasmid of claim 19 , wherein the plasmid comprises SEQ ID NO: 6.
26. The plasmid of claim 19 , wherein the plasmid comprises SEQ ID NO: 7.
27. A chimeric plasmid, comprising an origin of replication (ori) selected from the group consisting of pSC101, colE1, pBBR1 and RK2; and λ phage nucleic acid, wherein the λ phage nucleic acid comprises a) a nucleic acid encoding Beta, Gam and Exo operably linked to P L , b) O L and O R ; c) a nucleic acid encoding c1857; d) an N-kil deletion; and d) a nucleic acid encoding a selectable marker replacing a nucleic acid encoding rexAB;
wherein the chimeric plasmid does not comprises the N-kil region of lambda phage, and wherein bacterial host cells transformed with the plasmid can perform homologous recombination.
28. The plasmid of claim 27 , further comprising nucleic acid encoding Orf and repγ.
29. A method of producing a bacterial host cell that can perform homologous recombination, comprising introducing the plasmid of claim 27 into the bacterial host cell, thereby rendering the bacterial cell capable of performing homologous recombination.
30. The method of claim 29 , wherein the host cell is a gram negative bacterial cell.
31. The method of claim 29 , wherein the host cell is an Escherichia coli cell.