Strand breakage of coliphage λ DNA supercoils in infected lysogens. I. Genetic and biochemical evidence for two types of nicking processes

Roger McMacken, Sandra Kessler, Richard Boyce

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

After thermal induction of Escherichia coli lysogens infected with radioactive λ phage, nicks controlled by two processes appear in λ DNA supercoils within 5 min. One process is solely under control of λ gene N; the other is under control of λ genes N, O, and P. N-controlled nicks are not detected if NaCl is omitted from the postinduction wash medium at 4°, whereas OP-controlled nicks are. Moreover, N-controlled nicks are repaired in vivo, whereas OP-controlled nicks are not. OP-controlled nicks appear in λc17 DNA supercoils under conditions where they are replicating and being transcribed independently of cI repressor and N-mediated transcription. Thus, OP-controlled nicks are probably created by the replication process. N-controlled nicks appear to require N-mediated transcription, but the activity responsible for N-controlled nicking is not the product of an N-activated gene in the b2 region or from the region extending from attλ to gene N, since N-controlled nicking is normal for a deletion-addition mutant lacking these genes. The properties of N-controlled nicking suggest that the formation of N-type nicks is associated with the attachment of the phage chromosome to the bacterial membrane. Both nicking activities can be elicited in trans by heteroimmune phage, require inactivation of cI repressor, and are sensitive to rifampicin.

Original languageEnglish (US)
Pages (from-to)356-371
Number of pages16
JournalVirology
Volume66
Issue number2
DOIs
StatePublished - Aug 1975
Externally publishedYes

ASJC Scopus subject areas

  • Virology

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