title: Overproduction and purification of Bacillus subtilis DNA polymerase III.
abstract: The objectives of this work were to engineer the cloned polC gene encoding Bacillus subtilis DNA polymerase III for controlled overexpression in Escherichia coli and to devise a facile purification scheme permitting the large-scale production of pure recombinant polymerase. The translational signals of polC were restructured by expression cassette PCR (MacFerrin et al., 1990, Proc. Natl. Acad. Sci. USA 87, 1937-1941), and the modified gene was inserted into the expression plasmid, pKC30 (Rosenberg et al., 1983, in "Methods in Enzymology," Vol. 101, pp. 123-138, Academic Press, San Diego), under the strict control of the coliphage lambda pL promoter and its repressor, cI. When the system was derepressed at 32 degrees C, soluble DNA polymerase III accumulated at levels approximating 2% of total cellular protein. The recombinant protein was purified to greater than 99% purity by utilizing a tandem combination of Cibacron blue agarose, phenyl-Sepharose, and MonoQ FPLC chromatography. The properties of the purified recombinant protein were indistinguishable from those of native B. subtilis DNA polymerase III.
authors.affiliation: Department of Pharmacology, University of Massachusetts Medical School, Worcester 01655.
authors.forename: R A
authors.initials: RA
authors.lastname: Hammond
authors.forename: N C
authors.initials: NC
authors.lastname: Brown
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D001483:Base Sequence; D004258:DNA Polymerase III / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D004790:Enzyme Induction; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D010957:Plasmids; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins; D004258:DNA Polymerase III