Restriction of bacteriophage lambda by Escherichia coli K |
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Authors: | N E Murray P L Batten K Murray |
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Affiliation: | Medical Research Council Molecular Genetics Unit and Department of Molecular Biology University of Edinburgh, King''s Buildings Mayfield Road, Edinburgh EH9 3JR, Scotland |
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Abstract: | Derivatives of phage lambda, for which the numbers and positions of the recognition sites for endonuclease R. Ecok are known, were used as substrates for the Escherichia coli K restriction system in vivo and in vitro. A single unmodified recognition site was sufficient for a DNA molecule to be bound and broken by the K restriction enzyme. Although discrete fragments of DNA were not produced, the breaks were made preferentially in the proximity of the recognition site. Breakage of a DNA molecule with only one recognition site required a 10 to 40-fold higher concentration of restriction enzyme than breakage of a DNA molecule with two or more recognition sites, but these substrates were all equally effective in a binding assay for the enzyme.The polynucleotide kinase reaction provided no evidence for new 5′-terminal sequences generated by restriction in vitro; the 5′ termini were either refractory to the polynucleotide kinase reaction or had no sequence specificity. |
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