Cloning and/or sequencing vector

1. A method for propagating a cloning or sequencing vector that lacks an insert, said method comprising:

introducing said vector into a first prokaryotic cell, said cloning vector comprising a promoter operably linked to a nucleotide sequence encoding a CcdB poison protein, said cell expressing a CcdA antidote protein;

propagating said vector in said first prokaryotic cell, thereby expressing said CcdB poison protein without killing the cell; and

recovering the vector.

2. The method of claim 1 , further comprising introducing the vector lacking a nucleic acid insert into a second prokaryotic cell, said second prokaryotic cell being susceptible to said CcdB poison protein, thereby preventing growth of said second prokaryotic cell.

3. The method of claim 1 , wherein said first prokaryotic cell comprises a mutation at amino acid position 462 of Escherichia coli GyrA.

4. The method of claim 3 , wherein the mutation at amino acid position 462 of E. coli GyrA comprises replacement of arginine with a cysteine.

5. The method of claim 1 , wherein said vector comprises an origin of replication from the pUC series of plasmids.

6. The method of claim 5 , wherein said origin of replication is the origin of replication from pUC18 or pUC19.

7. A method of growing prokaryotic cells that comprise a cloning vector expressing a CcdB poison protein without selecting for prokaryotic cells containing mutations in the ccdB gene, comprising:

providing the prokaryotic cells with a gene encoding a CcdA antidote protein so as to antagonize the activity of the CcdB poison protein

providing said cells with a gene encoding E. coli GyrA having a mutation at amino acid position 462; and

growing said cells while expressing the CcdB poison protein.

8. The method of claim 7 , wherein the mutation at amino acid position 462 of GyrA comprises replacement of arginine with cysteine.

9. A method of growing prokaryotic cells that comprise a cloning vector encoding a CcdB poison protein comprising:

providing said prokaryotic cells with a cloning vector with a pUC origin of replication, said cloning vector also encoding the CcdB poison protein; and

providing said prokaryotic cells with E. coli GyrA having a mutation at amino acid position 462.

10. The method of claim 9 , wherein the mutation at amino acid position 462 of GyrA comprises replacement of arginine with cysteine.

11. The method of claim 9 , wherein said pUC origin of replication is the origin of replication from pUC 18 or pUC 19.

12. A method for propagating a cloning or sequencing vector that lacks an insert, said method comprising:

introducing said vector into a first prokaryotic cell, said cloning vector comprising a promoter operably linked to a nucleotide sequence encoding a CcdB poison protein, said cell expressing a polypeptide consisting of the 41 -carboxy terminal amino acids of a CcdA antidote protein;

propagating said vector in said first prokaryotic cell, thereby expressing the CcdB poison protein without killing the cell; and

recovering the vector.

13. The method of claim 12 further comprising introducing the vector lacking a nucleic acid insert into a second prokaryotic cell, said second prokaryotic cell being susceptible to the CcdB poison protein, thereby preventing growth of said second prokaryotic cell.

14. The method of claim 12 , wherein said first prokaryotic cell comprises a mutation at amino acid position 462 of E. coli GyrA.

15. The method of claim 14 , wherein the mutation at amino acid position 462 of GyrA comprises replacement of arginine with a cysteine.

16. The method of claim 12 , wherein said vector comprises an origin of replication from the pUC series of plasmids.

17. The method of claim 16 , wherein said origin of replication is the origin of replication from pUC 18 or pUC 19.

18. The method of claim 12 , wherein said vector comprises said nucleic acid encoding the CcdB poison protein and a nucleic acid encoding the 41 -carboxy terminal amino acids of the CcdA antidote protein.