Table 4.

Activation of gene expression by Ler

OperonSource of promoterβ-Galactosidase activityaFold activationb
pBR322pLER
LEE1 EHEC LEE111 ± 6100 ± 60.9
LEE2 EHEC LEE27 ± 4207 ± 147.6c
LEE3 EHEC LEE22 ± 5175 ± 228.1c
tir EHEC LEE10 ± 180 ± 167.6c
eae EHEC LEE34 ± 933 ± 20.9
LEE4 EHEC LEE861 ± 51942 ± 381.1
stx EHEC phage15 ± 420 ± 31.3
espP EHEC plasmid230 ± 11218 ± 80.9
hly EHEC plasmid1,169 ± 54951 ± 620.8
tagA EHEC plasmid12 ± 1245.3 ± 2019.5c
espC EPEC chromosome33 ± 31,027 ± 7031.0c
bfp EPEC plasmid85 ± 161 ± 0.20.7
bfpd EPEC plasmid2,836 ± 812,476 ± 1700.9
bla control1601701.1
  • a Mean β-galactosidase activity (in Miller units) present in bacteria containing indicated promoter-reporter fusion ± standard error. EHEC promoters were fused with a promoterless lacZ reporter and introduced as single-copy fusions into the chromosome of E. coli K-12 strain TE2680. These reporter strains were transformed with pBR322 or pSE1093, except for espC and bfp fusions, which were transformed with pSE1100 containing EPEC ler.

  • b β-Galactosidase activity of pLER divided by activity of pBR322.

  • c Significant at P = 0.05 compared to vector-only control.

  • d Plasmid pRS551 containingbfp::lacZ fusion in EPEC Δler or EPEC wild-type backgrounds, respectively.