Gf. King et al., The dimerization and topological specificity functions of MinE reside in astructurally autonomous C-terminal domain, MOL MICROB, 31(4), 1999, pp. 1161-1169
Correct placement of the division septum in Escherichia coli requires the c
o-ordinated action of three proteins, MinC, MinD and MinE. MinC and MinD in
teract to form a non-specific division inhibitor that blocks septation at a
ll potential division sites. MinE is able to antagonize MinCD in a topologi
cally sensitive manner, as it restricts MinCD activity to the unwanted divi
sion sites at the cell poles, Here, we show that the topological specificit
y function of MinE residues in a structurally autonomous, trypsin-resistant
domain comprising residues 31-88, Nuclear magnetic resonance (NMR) and cir
cular dichroic spectroscopy indicate that this domain includes both alpha a
nd beta secondary structure, while analytical ultracentrifugation reveals t
hat it also contains a region responsible for MinE homodimerization. While
trypsin digestion indicates that the anti-MinCD domain of MinE (residues 1-
22) does not form a tightly folded structural domain, NMR analysis of a pep
tide corresponding to MinE(1-22) indicates that this region forms a nascent
helix in which the peptide rapidly interconverts between disordered (rando
m coil) and alpha-helical conformations, This suggests that the N-terminal
region of MinE may be poised to adopt an alpha-helical conformation when it
interacts with the target of its anti-MinCD activity, presumably MinD.