pUC18, pUC19 DNA

pUC18/19 plasmids contain:

1. The pMB1 replicon rep responsible for the replication of plasmid (source – plasmid pBR322). The high copy number of pUC plasmids is a result of the lack of the rop gene and a single point mutation in the replicon rep of pMB1.
2. The bla gene, encoding beta-lactamase, confers resistance to ampicillin (source – plasmid pBR322). It differs from that of pBR322 by two point mutations
3. The region of E.coli lac operon containing a CAP protein binding site, promoter P_lac, lac repressor binding site and the 5’-terminal part of the lacZ gene encoding the N-terminal fragment of beta-galactosidase (source – M13mp18/19). This fragment, whose synthesis can be induced by IPTG, is capable of intra-allelic (alpha) complementation with a defective form of beta-galactosidase encoded by the host (mutation delta(lacZ)M15). In the presence of IPTG, bacteria synthesize both fragments of the enzyme and form blue colonies on media with X-Gal. Insertion of DNA into the MCS located within the lacZ gene (codons 6-7 of lacZ are replaced by MCS) inactivates the N-terminal fragment of beta-galactosidase and abolishes alpha-complementation. Bacteria carrying recombinant plasmids therefore give rise to white colonies

The map shows enzymes that cut pUC18/19 DNA once. Enzymes produced by Thermo Scientific are shown in orange. The coordinates refer to the position of the first nucleotide in each recognition sequence.

The exact positions of the genetic elements are shown on the map (termination codons included). The bla gene nucleotides 2486-2418 (complementary strand) code for a signal peptide. The LacZ polypeptide corresponding to wt beta-galactosidase and essential for blue/white screening ends at nt position 236 (compl. strand). Another 30 codons in the same reading frame are derived from pBR322. The indicated rep region is sufficient to promote replication. DNA replication initiates at position 866 (± 1) and proceeds in the direction indicated. Plasmids carrying the pMB1 and ColE1 replicons are incompatible, but they are fully compatible with those carrying the p15A replicon (pACYC177, pACYC184). pMB1-derived plasmids can be amplified using chloramphenicol.