Table 1.

Bacterial strains and plasmids used in this study

Strain or plasmidRelevant genotype or phenotypeSource or reference
Strains
E. coli K-12
  EB53 hemA aroB rpoB 40
  IR754EB53 buttonB::Kanr 42
  DH5αMCR recA1 mcrA mcrBC Bethesda Research Labs
H. ducreyi
 35000Wild type, parent strain; can utilize low levels of hemoglobin and high levels of hemeStanley Spinola, Indiana University
 FX50435000 hgbA::CAT, unable to utilize hemoglobin 13
 FX51435000 Δ(exbB exbD tonB)::CAT, unable to utilize hemoglobin 14
 FX51535000 ΔtdhA::CAT, can utilize low levels of hemoglobin and high levels of hemeThis work
Plasmids
 pBluescript(pBS)ColE1 replicon, Apr, high-copy cloning vectorStratagene
 pNC 40ColE1 replicon, Apr Cmr, source of CAT cassette for making insertional mutations 45
 pMCL 200p15A replicon, Cmr, low-copy cloning vector 30
 pHP 45Omega interposon, source of Strr/Spcr cassette for making insertional mutations 36
 pUNCH 579 hgbA in pBS, Apr, expresses functionalhgbA from own promoter 13
 pUNCH 563 exbB exbD tonB in pBS, Apr, expresses functional H. ducreyi Ton system from own promoter 14
 pUNCH 569 exbB exbD tonB, 3.5-kbXbaI-XhoI of pUNCH 563 in pMCL200This work
 pUNCH 1204Original tdhA clone, 2.9-kbSau3A insert in pBluescript which confers ability of IR754 pUNCH 569 to grow on hemeThis work
 pUNCH 663ΔtdhA::CAT, CAT cassette of pNC40 (1-kbBglII, fill-in) between two MluI sites of pUNCH 1204 (tdhA)This work
 pUNCH 665ΔtdhA::Omega, 2-kb SmaI from Omega in between two MluI sites of pUNCH 1204 (tdhA)This work
 pUNCH 667 tdhA, 2.9-kb XbaI-XmaI of pUNCH 1204 in pMCL200This work
 pUNCH 676 tdhA andexbB exbD tonB, 4-kb XhoI-PvuI of pUNCH 563 cloned between the SalI and PvuI sites of pUNCH 667This work