TABLE 1.

Bacterial strains and plasmids used in this study

Strain/plasmidRelevant characteristicsReference/source
Strains
    MC4100FaraD139 Δ(argF-lac)U139 rpsL150 flbB5301 ptsF25 deoC1 thi-1 rbsR relA 4
    PLB3260MC4100 ΔlamB106 ΦompF′::lacZ+S. Benson
    PLB3261MC4100 ΔlamB106 ΦompC′::lacZ+S. Benson
    RAM411PLB3261 ompC+zei::Tn10 (50% linkage to ompC by P1 transduction) 17
    RAM412PLB3261 ompC234 (OmpC1Cys) zei::Tn10 17
    RAM415PLB3261 ompC402 (OmpC2Cys) zei::Tn10 17
    RAM1126RAM415 degP::Kmr pCS10 5
    RAM1304RAM412 hfq1::ΩKmr (hfq null) pTrc99AThis study; 32
    RAM1305RAM412 hfq2-ΩKmr (hfq+) pTrc99AThis study; 32
    RAM1306RAM412 hfq1::ΩKmr (hfq null) pTrc99-ipeXThis study; 32
    RAM1307RAM412 hfq2-ΩKmr (hfq+) pTrc-ipeXThis study; 32
    CS109W1485 FC. Schnaitman
    CS137W1485 F PA-2 lysogenC. Schnaitman
Plasmids
    pACYC184Cmr Tcr; p15A replicon 6
    pC510pACYC-degPS210A30
    pBAD33Cmr; expression vector; p15A/M13 replicons 11
    pBR322Apr Tcr; pMB1 replicon 3
    pTrc99AApr; expression vector; pMB1 repliconPharmacia
    pTrc-ybcQThe ybcQ clone in pTrc99A encompassing ybcQ, ipeX and the 3′ end of nmpCThis study
    pybcQ plus SL-1 through SL-5The ybcQ clone in pTrc99A encompassing ybcQ and all five stem-loops of ipeXThis study
    pybcQ plus SL-2 through SL-5The ybcQ clone in pTrc99A encompassing ybcQ and stem-loops 2 to 5 of ipeXThis study
    pybcQ plus SL-3 through SL-5The ybcQ clone in pTrc99A encompassing ybcQ and stem-loops 3 to 5 of ipeXThis study
    pTrc-ipeXThe ipeX clone in pTrc99A containing all five stem loops of ipeX and the 3′ ends of ybcQ and nmpCThis study
    pTrc-ipeX (SL-2*)The ipeX clone in pTrc99A with a 3-base alteration in the stem-loop 2 of ipeXThis study
    pRAM1006A 3.0-kb HindIII chromosomal fragment containing ompC was cloned into a pSC101-derived plasmid (Apr Kmr)R. Misra
    pTrc-ompCA clone carrying the ompC coding region under the control of the pTrc99A promoterThis study
    pompC-UTR[ss]-phoAAn ompC-phoA chimeric clone in pACYC184 from which PhoA, with OmpC's signal sequence, was synthesized under ompC's transcriptional and translational controlsThis study
    pompC-UTR-phoAAn ompC-phoA chimeric clone in pACYC184; PhoA, with its native signal sequence, was synthesized under ompC's transcriptional and translational controlsThis study