Membrane binding by MinD involves insertion of hydrophobic residues within the C-terminal amphipathic helix into the bilayer.
MinD binds to phospholipid vesicles in the presence of ATP and is released by MinE, which stimulates the MinD ATPase. Membrane binding requires a short conserved C-terminal region, which has the potential to form an amphipathic helix. This finding has led to a model in which the binding of ATP regulates the formation or accessibility of this helix, which then embeds in the membrane bilayer. To test this model, we replaced each of the four hydrophobic residues within this potential helix with tryptophan or a charged residue. Introduction of a negatively charged amino acid decreased membrane binding of MinD and its ability to activate MinC. In contrast, mutants with tryptophan substitutions retained the ability to bind to the membrane and activate MinC. Fluorescence emission spectroscopy analysis of the tryptophan mutants F263W, L264W, and L267W confirmed that these tryptophan residues did insert into the hydrophobic interior of the bilayer. We conclude that membrane binding by MinD involves penetration of the hydrophobic residues within the C-terminal amphipathic helix into the hydrophobic interior of the bilayer.
Zhou
Huaijin
H
Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas 66160-7420, USA.
Lutkenhaus
Joe
J
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D005454:Fluorescence Polarization; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D009154:Mutation; D012984:Software; D014364:Tryptophan
D029968:Escherichia coli Proteins; D008051:Lipid Bilayers; D008565:Membrane Proteins; C462942:MinC protein, E coli; D014364:Tryptophan; D000251:Adenosine Triphosphatases; C072069:MinD protein, E coli