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.

Institute of Microbiology Academy of Sciences of the Czech Republic Prague Czech Republic

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Annu Rev Biochem. 1969;38:467-500 PubMed

Folia Microbiol (Praha). 1994;39(6):452-8 PubMed

J Mol Biol. 1970 May 28;50(1):111-27 PubMed

Mol Gen Genet. 1983;190(1):92-100 PubMed

Gene. 1992 Mar 1;112(1):21-7 PubMed

Nucleic Acids Res. 1993 Feb 11;21(3):373-9 PubMed

Genetics. 1954 Jul;39(4):440-52 PubMed

Folia Microbiol (Praha). 1985;30(1):17-24 PubMed

Mol Gen Genet. 1980;180(1):35-46 PubMed

Ann Inst Pasteur (Paris). 1954 Dec;87(6):653-73 PubMed

J Mol Biol. 1969 May 14;41(3):459-72 PubMed

J Bacteriol. 1953 Feb;65(2):113-21 PubMed

Genetics. 1965 Nov;52(5):1043-50 PubMed

J Biol Chem. 1981 Jul 25;256(14):7573-82 PubMed

Annu Rev Genet. 1991;25:585-627 PubMed

Mol Gen Genet. 1974;135(1):51-60 PubMed

J Bacteriol. 1971 May;106(2):539-42 PubMed

Nucleic Acids Res. 1979 Nov 24;7(6):1513-23 PubMed

Gene. 1977;2(2):95-113 PubMed

J Mol Biol. 1992 Oct 5;227(3):597-601 PubMed

J Bacteriol. 1978 Jun;134(3):1141-56 PubMed

Gene. 1990 May 31;90(1):125-8 PubMed

J Mol Biol. 1983 May 5;166(1):1-19 PubMed

Genet Res. 1969 Apr;13(2):227-40 PubMed

Virology. 1972 Jun;48(3):679-89 PubMed

Ann N Y Acad Sci. 1983;411:383-8 PubMed

Plasmid. 1985 Nov;14(3):224-34 PubMed

J Gen Microbiol. 1980 Jul;119(1):231-8 PubMed

Proc Natl Acad Sci U S A. 1989 Apr;86(7):2281-5 PubMed

Microbiol Rev. 1993 Jun;57(2):434-50 PubMed

Folia Microbiol (Praha). 1994;39(2):162-5 PubMed

J Gen Microbiol. 1972 Jul;71(2):403-5 PubMed

J Gen Microbiol. 1973 Dec;79(2):257-64 PubMed

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