TABLE 2.

actA expression as measured by GUS activity/OD600 for prfA mutant strains and LLO secretion as measured by Western analysis

StrainGenotype or descriptionactA-GUS activityLLO quantification
Avg valueaFold ΔbSecreted protein (ng)cFold Δb
NF-L1041Wild-type prfA17 ± 112.81
NF-L1009ΔprfA10 ± 00.60.20.1
NF-L1185prfA(E77K)279 ± 261735.512.7
NF-L1186prfA(G155S)437 ± 32640.814.6
NF-L1226prfA(G145S)7,273 ± 45643445.716.3
NF-L1011prfA(L140F)8,055 ± 39048152.818.9
  • a Experimental mean units of GUS activity ± standard deviations. actA-GUS data are taken from duplicate samples and are representative of three independent experiments.

  • b Severalfold change in induction relative to values for strains containing wild-type prfA.

  • c Experimental quantification of secreted LLO protein based on Western blot comparisons with defined amounts of recombinant LLO. LLO secretion data are representative of three independent experiments.