The effect of recA mutation on the expression of EcoKI and EcoR124I hsd genes cloned in a multicopy plasmid.
Type I restriction-modification (R-M) endonucleases are composed of three subunits--HsdR, required for restriction, and HsdM and HsdS which can produce a separate DNA methyltransferase. The HsdS subunit is required for DNA recognition. In this paper we describe the effect of cloned EcoKI and EcoR124I hsd genes on the resulting R-M phenotype. The variability in the expression of the wild type (wt) restriction phenotype after cloning of the wt hsd genes in a multicopy plasmid in Escherichia coli recA+ background suggests that the increased production of the restriction endonuclease from pBR322 is detrimental to the cell and this leads to the deletion of the cloned hsd genes from the hybrid plasmid and/or inactivation of the enzyme. The effect of a mutation in E. coli recA gene on the expression of R-M phenotype is described and discussed in relation to the role of the cell surface and the localization of the restriction endonuclease in the cell.
Hubácek
J
J
Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Holubová
I
I
Weiserová
M
M
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes / Q000235:genetics* / Q000378:metabolism; D015280:DNA Restriction-Modification Enzymes / Q000235:genetics / Q000378:metabolism; D015253:Deoxyribonucleases, Type I Site-Specific / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008278:Magnesium Sulfate / Q000494:pharmacology; D009154:Mutation; D010957:Plasmids / Q000235:genetics*; D011938:Rec A Recombinases / Q000235:genetics*; D013696:Temperature
D001426:Bacterial Proteins; D015280:DNA Restriction-Modification Enzymes; D029968:Escherichia coli Proteins; C113046:HSDS protein, Bacteria; D008278:Magnesium Sulfate; D011938:Rec A Recombinases; D004262:DNA Restriction Enzymes; C089629:endodeoxyribonuclease EcoKI; C048242:endodeoxyribonuclease EcoR124I; D015253:Deoxyribonucleases, Type I Site-Specific; C109830:HsdR protein, E coli