Relative toxin activities of CyaA-derived constructs.

aCapacity to catalyze conversion of ATP to cAMP.
bAC enzyme activity associated with J774A.1 cells (106/ml) upon incubation with 6 nM protein for 30 min at 4°C. Relative activity of intact CyaA was taken as 100%.
cDetermined as the amount of hemoglobin (A541 nm) released from washed sheep erythrocytes (5.108/ml) by 5 µg/ml of protein at 37°C.
dAmounts of intracellular cAMP per 105 J774A.1 cells incubated with indicated proteins for 30 min at 37°C.
eThe number of plus signs reflects the relative ability of CyaA proteins to increase [Ca2+]i levels (c.f. Fig. 2).
fDue to lack of AC enzyme activity, the capacity of these proteins to bind the J774A.1 cells could not be quantified directly. The capacity of these constructs to compete for the CD11b/C18 receptor with CyaA-biotin, however, is indistinguishable from that of intact CyaA (100% activity, data not shown).
gThe capacity to translocate the AC domain polypeptide could not be quantified for these constructs because of lack of AC enzyme activity. It can, however, be deduced from the capacity of corresponding constructs to deliver an inserted OVA epitope (SIINFEKL) into the cytosol of antigen-presenting cells for processing and subsequent presentation to specific CD8+ T cells in complex with major histocompatibility complex I molecules [63].