Y. Zhang et al., THE RELATIONSHIP BETWEEN HETERO-OLIGOMER FORMATION AND FUNCTION OF THE TOPOLOGICAL SPECIFICITY DOMAIN OF THE ESCHERICHIA-COLI MINE PROTEIN, Molecular microbiology, 30(2), 1998, pp. 265-273
MinE is an oligomeric protein that, in conjunction with other Min prot
eins, is required for the proper placement of the cell division site o
f Escherichia coli. We have examined the self-association properties o
f MinE by analytical ultracentrifugation and by studies of hetero-olig
omer formation in non-denaturing polyacrylamide gets. The self-associa
tion properties of purified MinE predict that cytoplasmic MinE is like
ly to exist as a mixture of monomers and dimers. Consistent with this
prediction, the C-terminal MinE(22-88) fragment forms hetero-oligomers
with MinE(+) when the proteins are co-expressed. In contrast, the Min
E(36-88) fragment does not form MinE(+)/MinE(36-88) hetero-oligomers,
although MinE36-88 affects the topological specificity of septum place
ment as shown by its ability to induce minicell formation when co-expr
essed with MinE(+) in wild-type cells. Therefore, hetero-oligomer form
ation is not necessary for the induction of mini-celling by expression
of MinE(36-88) in wild-type cells. The interference with normal septa
l placement is ascribed to competition between MinE(36-88),nd the corr
esponding domain in the complete MinE protein for a component required
for the topological specificity of septal placement.