Table 1.

Bacterial strains and plasmids used in this work

Strain or plasmidDescriptionSource and/or reference
Strains
 E1392/75ETEC strain expressing CS1, CS3, ST, LT, and streptomycin resistanceNCTCa
 E1392/75-2AE1392/75 derivative with LT and ST spontaneously deletedNCTC
 TG1Laboratory E. coli strain for general DNA manipulationsStratagene
 ET011E1392/75-2A cured of the plasmid that codes for CS1This work
 EC012TG1 expressing CS1 from pKCS1This work
 SY327λpir Nalr pir; host for maintenance of pCVD442 and derivatives28
 SM10λpir Kanr pir mobRP4; host for maintenance and mobilization of pCVD442 and derivatives35
 PTL001E1392/75-2A aroC htrA derivativeThis work
 PTL002E1392/75-2A aroC ompRderivativeThis work
 PTL003E1392/75-2A aroC ompC ompF derivativeThis work
Plasmids
 pKK223-3Expression vectorAmersham Pharmacia Biotech
 pKCS1CS1 expressed fromcooB gene cloned in pKK223-3This work
 pStrep6-kb plamid from E1392/75-2A coding for streptomycin resistance7; this work
 pCVD442 sacB suicide vector that codes for ampicillin resistance and requires pirfor replication12
 pCVDΔaroC pCVD442 derivative carrying ΔaroC fragmentThis work
 pCVDΔhtrA pCVD442 derivative carrying ΔhtrA fragmentThis work
 pCVDΔompR pCVD442 derivative carrying ΔompR fragmentThis work
 pCVDΔompC pCVD442 derivative carrying ΔompC fragmentThis work
 pCVDΔompF pCVD442 derivative carrying ΔompF fragmentThis work
  • a NCTC, National Collection of Type Cultures.