MinE

The MinE protein is one of three proteins of the Min system encoded by the minB operon required to generate pole to pole oscillations prior to bacterial cell division as a means of specifying the midzone of the cell, as seen in E.coli.

History

MinE was initially thought to assemble as a static ring at the cell center, thereby preventing the MinCD inhibition complex from localizing and binding there and instead influencing the complex to occupy each bacterial pole. [1] Raskin and de Boer later revealed a dynamic interaction of the Min proteins, where the unstable interaction between the proteins resulted in pole to pole oscillations, resulting in lower concentrations of MinCD complex at the cell center.

Function

MinE is a topological specificity factor that counters the activity of MinCD division inhibitor at the mid-cell division site. MinE will form as a dimer and will bind to membrane-bound MinCD complex, altering its binding dynamics.[2] It can only interact with membrane-bound MinD, suggesting a conformational change in MinD upon interacting with phospholipids that makes it vulnerable to MinE activity.

Deletion analysis has revealed that there exist two domains of interest in MinE, each with separate function.[3] The N-Terminal domain contains the anti-MinCD domain that is necessary and sufficient [1] to interact with MinD and counteract the MinCD-mediated division inhibition and to stimulate the ATPase activity of MinD, resulting in MinD’s detachment from the membrane after ATP hydrolysis.[4][5] MinE is also known to form a ring near each pole. The purpose of this ring structure is to catalyze the release of membrane-bound MinD in turn, imparting regional specificity of Min protein localization.[6]

Structure

Nuclear Magnetic Resonance (NMR) spectroscopy of truncated MinE revealed a long alpha-helix as well as two anti-parallel beta-strands. These structures are hypothesized to mediate the homodimerization by interaction of alpha/beta structures. These structural studies also support the theory that the MinE ring structure may actually form a multimeric filamentous structure as a function of the interaction of these alpha and beta units. It has also been hypothesized that MinE may potentially form higher order structures, and may not simply be limited to ring formation.[7]

Additional structural study and molecular imaging is needed to elucidate the higher order polymerization structures of MinE and to determine their dynamics on the remaining Min system. Recently, computational models have been applied to explore the limits of this system.[8]

References

  1. 1 2 Raskin DM, de Boer PA. (1997). "The MinE ring: an FtsZ-independent cell structure required for selection of the correct division site in E. coli.". Cell 91 (5): 685–94. doi:10.1016/S0092-8674(00)80455-9. PMID 9393861.
  2. ↑ Loose M, Fischer-Friedrich E, Herold C, Kruse S, Schwille P. (May 2011). "Min protein patterns emerge from rapid rebinding and membrane interaction of MinE". Nat. Struct. Mol Biol. 5 (In Press): 577–583. doi:10.1038/nsmb.2037. PMID 21516096.
  3. ↑ Pichoff S, Vollrath B, Touriol C, Bouché JP. (1995). "Deletion analysis of gene minE which encodes the topological specificity factor of cell division in Escherichia coli". Mol. Microbiol. 18 (2): 321–9. doi:10.1111/j.1365-2958.1995.mmi_18020321.x. PMID 8709851.
  4. ↑ Lu-Yan Ma, Glenn King, and Lawrence Rothfield (2003). "Mapping the MinE Site Involved in Interaction with the MinD Division Site Selection Protein of Escherichia coli". J Bacteriol. 185 (16): 4948. doi:10.1128/JB.185.16.4948-4955.2003. PMID 166455.
  5. ↑ Ma L, King GF, Rothfield L. (2003). "Positioning of the MinE binding site on the MinD surface suggests a plausible mechanism for activation of the Escherichia coli MinD ATPase during division site selection.". Mol. Microbiol. 54 (1): 99–108. doi:10.1111/j.1365-2958.2004.04265.x. PMID 15458408.
  6. ↑ Zonglin Hu, Cristian Saez, and Joe Lutkenhaus (2003). "Recruitment of MinC, an Inhibitor of Z-Ring Formation, to the Membrane in Escherichia coli: Role of MinD and MinE". J Bacteriol. 185 (1): 196–203. doi:10.1128/JB.185.1.196-203.2003. PMC 141945. PMID 12486056.
  7. ↑ Kang GB, Song HE, Kim MK, Youn HS, Lee JG, An JY, Chun JS, Jeon H, Eom SH. (2010). "Crystal structure of Helicobacter pylori MinE, a cell division topological specificity factor.". Mol. Microbiol. 76 (5): 1222–31. doi:10.1111/j.1365-2958.2010.07160.x. PMC 2883074. PMID 20398219.
  8. ↑ Mike Bonny, Elisabeth Fischer-Friedrich, Martin Loose, Petra Schwille, Karsten Kruse (2013). "Membrane Binding of MinE Allows for a Comprehensive Description of Min-Protein Pattern Formation". PLoS Comput Biol 9 (12): e1003347. doi:10.1371/journal.pcbi.1003347. PMID 1003347.
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