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Overproduction of Gene Products by the Super‐High‐Copy‐Number Plasmid pNR333
Author(s) -
Mochizuki Akihiko,
Horiuchi Sankichi,
Goto Nobuichi,
Nakaya Rintaro
Publication year - 1987
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1987.tb03135.x
Subject(s) - plasmid , biology , gene , escherichia coli , microbiology and biotechnology , chloramphenicol acetyltransferase , proteus mirabilis , low copy number , gene dosage , pbr322 , origin of replication , t dna binary system , kanamycin , genetics , vector (molecular biology) , gene expression , recombinant dna , reporter gene
The plasmid pNR333 is a kanamycin‐resistant, deletion derivative of pNR113 with an extremely high copy number in Escherichia coli and in Proteus mirabilis . In order to determine the usefulness of pNR333 as a replication gene of vector, the genes encoding chloramphenicol acetyltransferase (CAT) and β ‐galactosidase ( β ‐gal) were cloned individually into both pNR333 and other low‐copy‐number plasmids. The expression of the cloned genes was compared by measuring the specific activity of each enzyme and the amounts of the proteins produced. A hybrid plasmid pNR333‐ cat expressed 53 times as much activity of CAT as the low‐copy plasmid S‐a which had a copy number of four. The lacZ gene cloned in pNR333 produced 17 times as much β ‐gal as in the low‐copy‐number plasmid pNR1150. These results suggest that pNR333 is a useful vector plasmid for producing a large amount of polypeptides in E. coli hosts.