Restriction Endonuclease B and f1 Heteroduplex DNA

• Published in: Nature. New biology (London) Vol. 246; no. 149; pp. 13 - 16
• Main Authors: VOVIS, GERALD F, HORIUCHI, KENSUKE, HARTMAN, NEIL, ZINDAR, NORTON D
• Format: Journal Article
• Language: English
• Published: England 07-11-1973
• Subjects: Centrifugation, Density Gradient; Coliphages; DNA, Circular - metabolism; DNA, Single-Stranded - metabolism; DNA, Viral - analysis; DNA, Viral - biosynthesis; DNA, Viral - metabolism; Endonucleases - metabolism; Escherichia coli - enzymology; Hydrolysis; Mutation; Nucleic Acid Hybridization; Phosphorus Isotopes; Tritium
• ISSN: 0090-0028; 2058-1092
• DOI: 10.1038/newbio246013a0

In many strains of Escherichia coli, strain-specific restriction system recognises phage and bacterial DNA synthesised in a different strain and initiates its degradation. The recognition and initial hydrolysis can apparently occur at the same or different sites on the DNA molecule (resistance transfer factor R1 (refs 1-3) and E. coli B4 restriction, respectively) and are mediated by a strain-specific endonuclease. Protection is afforded by modification (glucosylation5-7 and methylation8,9) and mutation10 of the DNA, presumably at the recognition site(s). A DNA duplex, only one of whose strands is modified (by methylation), is resistant to restriction endonuclease K11. Similar conclusions about the sensitivity of hybrid molecules containing one modified DNA strand were made from in vivo observations with T212 and λ13 phage with regard to restriction in E. coli B and Pl lysogens, respectively.