TABLE 1.

Bacterial strains

E. coli strain	Genotype	Reference or construction
HB181	B/r A malK+ Δ(argF-lacIOZYA) phe(Am) thr(Am) hsdR/M (K-12)	35
VH2732	MC4100 ΔrelA251::kan argA::Tn10 malB::malE′-rrnB UAR-P1-φX174E′-′lacZ-T1T2-kan-T1T2-′malKa	12
XZ241	HB181 ΔrelA251::kan argA::Tn10 spoT+ malB::malE′-rrnB UAR-P1-box BAC-λ′-lacZ-T1T2-kan-T1T2-′malK	Zhang and Bremer, unpublished data; the ΔrelA251::kan argA::Tn10 alleles of VH2732 were transduced with phage P1 into XZ213 (reference 35), selecting for Tcr and screening for the Rel− phenotype
SL104	HB181 malB::malE′-Pspc-lacZ-T1T2-kan-T1T2-′malK	17
SL106	HB181 malB::malE′-Pspc-rplN-lacZ-T1T2-kan-T1T2-′malK	17
SL111	SL104 ΔrelA251::kan	The ΔrelA251::kan argA::Tn10 alleles from XZ241 were transduced with phage P1 into SL104, selecting for Tcr and screening for the RelA phenotype; the strain was cured of Tn10 and checked for Arg+
YX101	HB181 malB::malE′-PRNAI-lacZ-T1T2-kan-T1T2-′malK	Construction as described for SL104, except that a PRNAI promoter fragment was cloned
YX102	HB181 malB::malE′-PRNAII-lacZ-T1T2-kan-T1T2-′malK	Construction as described for SL104, except that a PRNAII promoter fragment was cloned
YX103	YX101 ΔrelA251::kan	The ΔrelA251::kan argA::Tn10 alleles from XZ241 were transduced with phage P1 into YX101, selecting for Tcr and screening for the RelA phenotype; the strain was then cured of Tn10 and checked for the Arg+ phenotype
YX104	YX102 ΔrelA251::kan	Construction as described for YX103, except that strain XZ102 was used as a recipient

^aT1T2, transcription terminators of the rrnB operon.