The dimerization and topological specificity functions of MinE reside in a structurally autonomous C-terminal domain.
Correct placement of the division septum in Escherichia coli requires the co-ordinated action of three proteins, MinC, MinD and MinE. MinC and MinD interact to form a non-specific division inhibitor that blocks septation at all potential division sites. MinE is able to antagonize MinCD in a topologically sensitive manner, as it restricts MinCD activity to the unwanted division sites at the cell poles. Here, we show that the topological specificity function of MinE residues in a structurally autonomous, trypsin-resistant domain comprising residues 31-88. Nuclear magnetic resonance (NMR) and circular dichroic spectroscopy indicate that this domain includes both alpha and beta secondary structure, while analytical ultracentrifugation reveals that 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 peptide corresponding to MinE1-22 indicates that this region forms a nascent helix in which the peptide rapidly interconverts between disordered (random 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.
King
G F
GF
Department of Biochemistry, University of Sydney, NSW, Australia. glenn@biochem.usyd.edu.au
Rowland
S L
SL
Pan
B
B
Mackay
J P
JP
Mullen
G P
GP
Rothfield
L I
LI
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002942:Circular Dichroism; D019281:Dimerization; D004926:Escherichia coli / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014461:Ultracentrifugation
D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D029968:Escherichia coli Proteins; C093548:MinE protein, E coli