TABLE 1.

E. coli strains and plasmids

Strain or plasmidRelevant genotypeReference or source
Strains
    DM49lexA329
    FC526ΔrecG263::kan11
    GY8322Δ(srlR-recA)306::Tn10S. Sommer; ENZ280 (8) carrying the K5353 mini-F plasmid (9)
    SMR821lexA3 malB::Tn933
    SMR1827FC40 sulA21133
    SMR4562arec+attλ+33; genotype identical to FC40 (4)
    SMR4649FC40 sulA211 lexA5133
    SMR5078recB21 recC22 sbcB15 sbcC201 hsdrKmK+xis1 cIts857)14
    SMR5156SMR4562 (λxis1 cIts857)SMR4562 × λSR446 (14)
    SMR5201recB21 recC22 sbcB15 sbcC201 hsdrKmK+ Δattλ::ampRCSMR5078 × DNA from pJP2
    SMR5222SMR4562 Δattλ::ampRCSMR 5156 × P1 SMR5201
    SMR5225SMR5222 Δ(srlR-recA)306::Tn10SMR5222 × P1 GY8322
    SMR5578SMR5222 ΔrecG263::kanSMR5222 × P1 FC526
    SMR5652SMR5222 ΔrecG263::kan Δ(srlR-recA)306::Tn10SMR5578 × P1 GY8322
    SMR5701SMR1827 (λxis1 cIts857)SMR1827 × λSR446
    SMR5702SMR4649 (λxis1 cIts857)SMR4649 × λSR446
    SMR5715SMR5222 lexA3 malB::Tn9SMR5222 × P1 SMR821
    SMR5725SMR5222 sulA211 lexA51SMR5702 × P1 SMR5201
    SMR5749SMR5222 sulA211SMR5701 × P1 SMR5201
Plasmids
    pEc1cE. cloacae ampRC+35
    pJP2pTGV-light ampRC+This work
    pJP19pACYC184 ampD+This workb
  • a Full genotype is Δ(lac-pro)XIII thi ara Rifr [F′ α45, lacIq lacI33ΩlacZ].

  • b Plasmid pJP19, carrying the E. coli ampD+ gene and promoter, was created by amplifying ampD+ from E. coli wild-type strain MG1655 (3) chromosomal DNA using primers AmpD no. 1, 5′-GGGTTTTCATGAGAGGCGGCATGTTAAAACTCCAG-3′; and AmpD no. 2, 5′-GGGTTTAAGCTTTCATGTTGTCTCCTTGCTGACCAG-3′. The primers incorporate terminal BspHI and HindIII restriction sites at the 5′ and 3′ ends (respectively) of the amplified fragment. Amplified ampD+ DNA and pACYC184 DNA (5) were digested with BspHI and HindIII, and the ampD+ fragment was ligated into pACYC184. pJP19-mediated ampD expression was confirmed by complementation to β-lactam sensitivity of four independent ampD β-lactam-resistant mutants.