The role of the FtsZ protein (SfiB) in UV-induced division inhibition and in the normal Escherichia coli cell division cycle.

This paper describes some of the major characteristics of the SOS-dependent division arrest which occurs in Escherichia coli during repair of DNA damage following UV irradiation. We shall review the evidence that the inducible division inhibitor, SfiA, interacts directly with an essential division protein, FtsZ. On the basis of its pivotal role in division inhibition during the UV stress response and other properties of ftsZ, we propose that this is a key gene involved in the actual regulation of the division cycle in E. coli. We also propose that at least some components of the division machinery interact to form a specific complex which we designate as a "septalsome". We shall discuss the possibility that a critical concentration of FtsZ is required to trigger the formation of an active septalsome prior to division. Alternatively, FtsZ might act to inhibit the formation of an active septalsome until a critical point in the cell cycle is reached.