The Switch I and II Regions of MinD Are Required for Binding and Activating MinC

Abstract

MinD and MinC cooperate to form an efficient inhibitor of Z-ring formation that is spatially regulated by MinE. MinD activates MinC by recruiting it to the membrane and targeting it to a septal component. To better understand this activation, we have isolated loss-of-function mutations in minD and carried out site-directed mutagenesis. Many of these mutations block MinC-MinD interaction; however, they also prevent MinD self-interaction and membrane binding, suggesting that they affect nucleotide interaction or protein folding. Two mutations in the switch I region (MinD box) and one mutation in the switch II region had little affect on most MinD functions, such as MinD self-interaction, membrane binding, and MinE stimulation; however, they did eliminate MinD-MinC interaction. Two additional mutations in the switch II region did not affect MinC binding. Further study revealed that one of these allowed the MinCD complex to target to the septum but was still deficient in blocking division. These results indicate that the switch I and II regions of MinD are required for interaction with MinC but not MinE and that the switch II region has a role in activating MinC.

MinC Mutants Deficient in MinD- and DicB-Mediated Cell Division Inhibition Due to Loss of Interaction with MinD, DicB, or a Septal Component

“…MalE-MinC 116-231 was purified as described previously (15,40). Mutants R133A and R172A were purified by using the same procedure.…”

“…These steps can be bypassed by overexpressing MinC 25-to 50-fold (6,15). The fact that a MinD E126A mutant can target MinC to the septum but cannot fully activate MinC indicates that there is a step beyond septum targeting (40).…”

Emerging facets of plastid division regulation

“…The elegant interplay and accurate temporal and spatial relationship between the Min proteins in E. coli is well established. In the presence of ATP, membrane-bound MinD interacts with MinC, an inhibitor of FtsZ polymerization, preventing the formation of a Z-ring at the polar ends of the cell and subsequent asymmetrical division (Szeto et al 2002;Hu and Lutkenhaus 2003;Zhou and Lutkenhaus 2004). MinE, a topological speciWcity factor, can then interact with membrane-bound MinC-MinD, activating MinD ATPase activity leading to MinD membrane dissociation, ultimately causing MinD to oscillate to the opposite side of the cell.…”

Modeling Three-Dimensional Spatial Regulation of Bacterial Cell Division (Dissertation)

“…MinE, however, induces the MinD ATPase activity on the membrane, causing hydrolyzed MinD ADP to be released into the cytoplasm and membrane-associated MinD ATP to localize into a polar zone that oscillates between the poles with a period of approximately 1 minute (Hu and Lutkenhaus, 2001). The FtsZ inhibitor, MinC piggybacks on the oscillating MinD ATP (Hu et al, 2003;Zhou and Lutkenhaus, 2004), ensuring that its time-averaged concentration is lowest at the midcell for the Z-ring assembly while sufficiently high at the poles to abrogate nascent FtsZ polymers .…”