title: Purification of pT181-encoded repC protein required for the initiation of plasmid replication.
abstract: The plasmid pT181 of Staphylococcus aureus consists of 4437 base pairs and encodes resistance to tetracycline. Initiation of pT181 replication specifically requires the plasmid-encoded repC protein. An in vitro system has been shown to carry out semiconservative replication of pT181 and its derivative plasmids (Khan, S A., Carleton, S. M., and Novick, R. P. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 4902-4906). We have used this replication assay to isolate repC protein, which was purified to near homogeneity. The repC gene was cloned into the pKJB825 plasmid that contains the phage lambda temperature-sensitive repressor gene, cI857, and the rightward promoter, PR. Upon temperature induction, Escherichia coli clones containing the recombinant plasmid overproduced repC protein, which was purified in significant quantities. The molecular weight of repC protein under denaturing conditions is 38,000, which is consistent with the size predicted from the DNA sequence data. Presence of repC protein was absolutely essential for the initiation of replication of pT181 and its derivatives in vitro.
authors.forename: R R
authors.initials: RR
authors.lastname: Koepsel
authors.forename: R W
authors.initials: RW
authors.lastname: Murray
authors.forename: W D
authors.initials: WD
authors.lastname: Rosenblum
authors.forename: S A
authors.initials: SA
authors.lastname: Khan
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification*; D002499:Centrifugation, Density Gradient; D003001:Cloning, Molecular; D004261:DNA Replication; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004351:Drug Resistance; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D008970:Molecular Weight; D009876:Operon; D010957:Plasmids; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; C043650:RepC protein, Staphylococcus aureus; D004262:DNA Restriction Enzymes; D013752:Tetracycline