Table 3.

Ratios of CAT activities to TEM β-lactamase activities of cells containing the different promoters cloned into pLQ943

Gene or promoterPlasmidPromoteraCAT activity/TEM β-lactamase activity ratiob in:
−35←bp→−10E. coliHB101K. oxytoca SL901
bla OXY-1 pLQ944c TTGTCA 17 bp GATAGT 614 ± 8663 ± 126
pLQ945 ------ 17 bp ----A- 6,810 ± 1648,670 ± 564
pLQ946 ------ 17 bp T----- 13,000 ± 56028,000 ± 3,030
pLQ947 ---A-- 17 bp ------ 11,000 ± 1,10013,300 ± 1,190
bla OXY-2 pLQ948 ---A-- 17 bp ----A- 32,300 ± 3,22076,800 ± 10,100
tac c pLQ949 ---A-- 16 bp T---A- 35,000 ± 2,68079,400 ± 6,970
  • a The 360-bpBamHI-HindIII fragments of plasmids derived from pKK232-8 (Table 2) were subcloned in pLQ943.

  • b Ratios of CAT activities to β-lactamase activities (see footnote b of Table 2 for units). All measurements were made with at least three independent determinations. The background CAT activity (pLQ943) in this assay was not detectable.

  • c pLQ944 and tac promoters were derived from plasmids pLQ925 and pLQ941, respectively (Table 2).