TABLE 1.

Bacterial strains and plasmids used in this study

Strain or plasmid	Descriptiona	Source or referenceb
Strains
BW934	Same as KL16 but with deoA22	3
BW1614	Same as KL16 but with thyA::Tn10dtet	This studyc
BW1670	λcI857 Δ(cro-bio) Δ(argD-lac)169 IN(rrnD-rrnE) hsdR2 mdoB202::Tn10	P1(LCK8) × HME5d
BW1670 ΔyjjG strain	Same as BW1670 but with ΔyjjG::cat; replacement of nt 1 through nt 624 of yjjG (677 nt)	This studye
BW1712	Same as KL16 but with ΔyjjG::cat	P1(BW1670 ΔyjjG) × KL16
BW1835	Same as KL16 but with thyA::Tn10dtet ΔyjjG::cat	P1(BW1712) × BW1614
HME5	λcI857 Δ(cro-bio) Δ(argD-lac)169 IN(rrnD-rrnE)	19
KL16	Hfr KL16 (PO-45) thi-1 relA-1 spoT1	CGSC
LCK8	hsdR2 mdoB202::Tn10 lacY1 or Δ(cod-lacI)6 galK2 galT22 metB1 glnV44	CGSC
Plasmids
pBAD28	ori p15a, araC, arabinose PBAD promoter, cat, bla	4
pBAD28::yjjG	pBAD28 with SacI-XbaI segment replaced by PCR-amplified yjjG gene and synthetic ribosome binding sitef	This studyf

^aAll strains are derivatives of E. coli K-12 and are F⁻ λ⁻ unless stated otherwise. cat, tet, and bla are genes specifying resistance to chloramphenicol, tetracycline, and carbenicillin, respectively.

^bTransductions with phage P1 dam rev6 (14) are described as follows: P1(donor) × recipient. CGSC, E. coli Genetic Stock Center, Yale University, New Haven, CT (http://cgsc.biology.yale.edu).

^cRandom mini-Tn10 insertions were produced from λ1048 as described previously (18), and a thymine-requiring mutant was selected by trimethoprim resistance (5). The thyA::Tn10dtet mutation was then transduced into strain KL16 by selection for tetracycline resistance.

^dTetracycline-resistant transductants were screened for the restriction-negative (HsdR⁻) phenotype by cross-streaking to test for resistance to phage λvir grown on E. coli C and sensitivity to λvir grown on E. coli K-12.

^eTransformation (19) of BW1670 was carried out with a PCR product of plasmid pKD3 (2). The primers used were 5′-TCATGGCGTTGCCAATCAGTATGTAATACAAGGTGGAATAGTGTAGGCTGGAGCTGCTTC-3′ and 5′-CCAGTTCGTGCAACGAAGAAACGGTCCAGGTGGGCGCGATCATATGAATATCCTCCTTAG-3′.

^fUsing strain KL16 DNA as a template, yjjG was amplified by PCR with Vent DNA polymerase (New England Biolabs) and the following two primer pairs: (i) 5′-AGCTCAGGAGGAATTCACCATGAAGTGGGACTGGATTTTC-3′ and 5′-CTAGATCAGTGTTTACACAGGAGCTG-3′ and (ii) 5′-CAGGAGGAATTCACCATGAAGTGGGACTGGATTTTC-3′ and 5′-ATCAGTGTTTACACAGGAGCTG-3′. The PCR products were purified with a QIAquick PCR spin column (QIAGEN Corp.) and then combined, heat denatured, and reannealed so that one-fourth of the molecules had protruding tetranucleotide ends that could be ligated to pBAD28 that had been treated with SacI and XbaI.