Figure 1.

Subunits of VacA. The VacA toxin is initially secreted as a polypeptide of about 88 kDa. The toxin is easily cleaved to yield the two subunits p34 and p58. Both subunits stay connected by non-covalent interactions. Different values were reported for the precise size of the subunits. Reliable data obtained by mass spectrometry were published by Nguyen et al.⁸ The name VacA refers to the ability of the toxin to cause a formation of vacuoles in target cells.⁴,⁵ For entry into the cells, both the p58 part and a segment of p34 are required. Correspondingly, vacuolization is dependent on the p34 part and a portion of p58. Upon cytosolic expression, p34 alone is sufficient to trigger cell death.⁶ The upper part shows the N-terminal residues of p34.