The dimerization and topological specificity functions of MinE reside in a structurally autonomous C‐terminal domain

Abstract

SummaryCorrect 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 ␣ and ␤ 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 MinE 1-22 indicates that this region forms a nascent helix in which the peptide rapidly interconverts between disordered (random coil) and ␣-helical conformations. This suggests that the N-terminal region of MinE may be poised to adopt an ␣-helical conformation when it interacts with the target of its anti-MinCD activity, presumably MinD.

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

“…Therefore, because the polar zone still appeared, the ATPase activation function in the MinE N-terminal domain is likely at a very low basal level when the C-terminal domain is disrupted. Thirdly, the truncated N-terminal domain, which forms a nascent helix (King et al, 1999), can autonomously bind to the membrane in the absence of MinD (Ma et al, 2003), and in the full length MinE, the binding domain is thought to be exposed upon membrane recruitment by MinD (Ma et al, 2003). This further supports our theory that MinE constituting the E-ring remained transiently attached to the membrane independently after recruited by MinD.…”

“…The C-terminal also contains the homodimerization domain of MinE (King et al, 1999). Hence, effective homodimerizations of MinE may play a significant role in E-ring, especially since it is made up of dense MinE.…”

The tail of the ParG DNA segregation protein remodels ParF polymers and enhances ATP hydrolysis via an arginine finger-like motif

“…We propose that the N-terminal domain of MinE might activate MinD ATP hydrolysis by an arginine finger-like mechanism, supplying one or both conserved arginines in trans into the ATP-binding pocket in MinD. Moreover, this charge-balancing strategy of ATPase activation might be a universally conserved feature of regulatory partners of ParA-like proteins, including Spo0J implicated in chromosome (21,22,36). The E. coli MinE N-terminal domain (residues 1-35) is predicted to consist of an extended or nascent helix (22).…”

“…Thus, ParG and MinE are small, dimeric proteins that influence nucleotide hydrolysis and polymerization of their cognate ParA homologs. Furthermore, the C termini of both proteins are well structured, albeit with different topologies, with more disordered N termini (6,21,22). Intriguingly, the MinE N terminus is required for stimulation of ATP hydrolysis by MinD (19), just as for the ParG-ParF pair.…”

Proteome-wide Subcellular Topologies of E. coli Polypeptides Database (STEPdb)

“…However, this is not the case for all secreted proteins some of which have no readily identifiable "export signals" or even use "piggy-back" mechanisms or undergo the so called nonclassical secretion (16). Additional secondary structural elements such as TMs (17,18), beta-barrels (19 -21), amphiphilic alpha-helical anchors (22)(23)(24) and functional domains such as peptidoglycan (25,26) and DNA (27,28) binding domains can also serve as indicators of subcellular location.…”