Genetics. Published Articles Ahead of Print: June 14, 2005, Copyright © 2005
doi:10.1534/genetics.105.042341


A more recent version of this article appeared on August 1, 2005.

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NinR- and Red-mediated phage-prophage marker rescue recombination in E. coli: recovery of a nonhomologous imm{lambda} DNA segment by infecting {lambda}imm434 phages

Sidney Hayes 1*, Kengo Asai 1, Audrey M Chu 1 and Connie Hayes 1

1 University of Saskatchewan

* To whom correspondence should be addressed. E-mail: hayess{at}duke.usask.ca.

Submitted on February 21, 2005
Revised on March 28, 2005
Accepted on 9 May 2005


Abstract

We examined the requirement of ë recombination functions for marker rescue of cryptic prophage genes within the Escherichia coli chromosome. We infected lysogenic host cells with ëimm434 phages and selected for recombinant immë phages that had exchanged the imm434 region of the infecting phage for the heterologous 2.6 Kb immë region from the prophage. Phage-encoded activity, either provided by Red, or by NinR functions, was required for the substitution. Red- phages with ÄNinR, or internal NinR deletions of rap-ninH, or orf-ninC were 117-, 12-, and five-fold reduced for immë rescue in a Rec+ host, suggesting the participation of several NinR activities. RecA was essential for NinR-dependent immë rescue, but had slight influence on Red-dependent rescue. Host recombination activities RecBCD, RecJ and RecQ participated in NinR-dependent recombination while they served to inhibit Red-mediated immë rescue. The opposite effects of several host functions toward NinR- and Red-dependent immë rescue explains why the independent pathways were not additive in a Rec+ host and why the NinR-dependent pathway appeared dominant. We measured the influence of the host recombination functions and DnaB on the appearance of orië-dependent replication initiation, and if orië replication initiation was required for immë marker rescue.

Key Words: DnaB, RecA, RecBCD, RecJ, E. coli recombination functions, Red, NinR, Orf, Rap, coliphage lambda recombination, lambda replication