Specific interaction of the intermediate filament protein vimentin and its isolated N-terminus with negatively charged phospholipids as determined by vesicle aggregation, fusion, and leakage measurements.
The interaction of the intermediate filament protein vimentin and its non-alpha-helical N-terminus with phosphatidylserine and phosphatidylinositol small unilamellar vesicles was investigated by measuring vesicle aggregation, fusion, and leakage. While the N-terminus suppressed Ca2(+)-induced fusion of phosphatidylserine vesicles, it caused their rapid aggregation in the absence of Ca2+; at a molar ratio of lipid to polypeptide of 25:3, the polypeptide/lipid complexes precipitated from the reaction mixture. This aggregation was efficiently diminished by NaCl. The phosphatidylinositol vesicles, on the other hand, became leaky when interacting with the N-terminus of vimentin, even at a molar ratio of lipid to polypeptide of 500:1. The leakage of phosphatidylinositol vesicles was suppressed by the addition of Ca2+ or NaCl to the reaction mixture. Intact vimentin also caused leakage of phosphatidylinositol vesicles, at low and high salt concentration. The results indicate specific and differential interactions of the N-terminus of vimentin with various negatively charged lipid species, although there is an electrostatic component common to these interactions.
Horkovics-Kovats
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Max-Planck-Institut für Zellbiologie, Rosenhof, Ladenburg, Federal Republic of Germany.
Traub
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D000595:Amino Acid Sequence; D002118:Calcium / Q000494:pharmacology; D008081:Liposomes / Q000378:metabolism*; D008561:Membrane Fusion / Q000187:drug effects; D008563:Membrane Lipids / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism*; D010539:Permeability / Q000187:drug effects; D010713:Phosphatidylcholines / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D014746:Vimentin / Q000378:metabolism*
D008081:Liposomes; D008563:Membrane Lipids; D010446:Peptide Fragments; D010713:Phosphatidylcholines; D010716:Phosphatidylinositols; D010718:Phosphatidylserines; D010743:Phospholipids; D014746:Vimentin; C066950:vimentin (1-96); D012965:Sodium Chloride; D002118:Calcium