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Table 1 Effects of arginine and ArgR on gltB::lacZ expression

From: Integration of regulatory signals through involvement of multiple global regulators: control of the Escherichia coli gltBDF operon by Lrp, IHF, Crp, and ArgR

Effect tested Strain/condition LacZ activity (units)1 Normalized data
  LP1000 (rph) 11722 (1.00)
Addition of arginine3 LP1000 + Arg 660 0.56
  LP1270 900 0.77
  LP1270 + Arg 953 0.81
  LP2020 (rph+) 736 0.63
  LP2020 + Arg 402 0.34
Deletion of ArgR LP1050 (ΔargR) 2981 2.54
  LP1050 + Arg 3035 2.59
  LP2020 (rph+)4 648 0.55
  LP2023 (rph+ ΔargR) 1283 1.09
  1. 1 One unit of LacZ (β-galactosidase) activity is defined as 1 nmol of ONPG hydrolyzed per min.
  2. 2 Samples were taken at several culture densities, and the resulting LacZ activity was plotted vs. culture density (as in Fig. 6). The activity was calculated from the slope of the line; in every case, the correlation coefficient of the least squares regression was ≥ 0.99.
  3. 3 Arginine hydrochloride was added to the medium to a final concentration of 7.5 mM.
  4. 4 These results were obtained on a different day from the other experiments.