A Novel Mechanism of Programmed Cell Death in Bacteria by Toxin–Antitoxin Systems Corrupts Peptidoglycan Synthesis
Figure 2
PezT from S. pneumoniae and zeta from S. pyogenes phosphorylate UNAG.
(A) Samples containing 0.25 mM UNAG, 5 mM MgCl2, 1 mM ATP, and 1 µM PezTΔC242 (red) or additionally 1 µM PezA antitoxin (black) were analyzed by anion exchange chromatography after 1 h of incubation at 25°C. The asterisk indicates the retention volume of the product formed by PezTΔC242 in the absence of the antitoxin PezA. (B) Analysis of the equivalent reaction using 1 µM epsilon/zeta complex from S. pyogenes after 1 h (dark red) and 24 h (red) of incubation. The asterisk indicates the retention volume of the product formed by zeta. Note that UNAG turnover was slow because of the presence of stoichiometric amounts of the antitoxin epsilon. However, in contrast to the PezAT system, zeta is not entirely inhibited. This difference is most probably caused by the different TA affinities in the two TA systems [11],[46]. (C) Schematic reaction mechanism of UNAG-3P formation by zeta toxins.