Calmodulin-dependent enzymes as a target of staphylococcal enterotoxin A

The response of lymphoid and nerve cells to the action of SEA has been investigated. It has been established that the toxin acts as a mitogen with respect to resting cells and suppresses the DNA biosynthesis in proliferating cells. Interaction of SEA with the systems of second messengers in lymphoblastoid cells has been studied. The results obtained suggest a mechanism of the antiproliferative action of SEA on these cells. Studies on the structural organization of the toxin molecule have revealed that the latter contains a polypeptide (BacM) capable of activating calmodulin-dependent enzymes both in the presence and absence of Ca2+. These findings permit us to assume that the cytostatic effect of SEA is conditioned by the formation of BacM and phosphorylation of elongation factor 2.