Aliphatic aldehydes promote myelin basic protein-induced fusion of phospholipid vesicles

Surewicz, Witold K.; Epand, Richard M.; Vail, William J.; Moscarello, Mario A.

doi:10.1016/0005-2736(85)90127-0

Cited by 7 publications

(3 citation statements)

References 26 publications

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“…Lipid Mixing Assay. Peptide-induced fusion of LUV was measured by the fluorescence resonance energy transfer between NBD-PE and Rh-PE (Struck et al, 1981) essentially as described previously (Surewicz et al, 1985). In brief, fusion was initiated by addition of the peptide in methanol or dimethyl sulfoxide to a mixture of LUV labeled with both NBD-PE and Rh-PE at 1 mol % each and unlabeled LUV at a molar ratio of 1:6.…”

Section: Methodsmentioning

confidence: 99%

“…The mixture was incubated while being shaken for 30 min at room temperature, and then fluorescence spectra were recorded using excitation at 450 nm. The percentage of fusion (lipid intermixing) was determined from the extent of resonance energy transfer in a given sample and the appropriate calibration curve (Surewicz et al, 1985). Circular Dichroism.…”

Section: Methodsmentioning

confidence: 99%

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Membrane Interaction and Conformational Properties of the Putative Fusion Peptide of PH-30, a Protein Active in Sperm-Egg Fusion

Muga

Neugebauer²,

Hirama³

et al. 1994

Biochemistry

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A peptide representing the putative fusion domain of PH-30, a sperm surface protein involved in sperm-egg fusion, was synthesized, and its interaction with model lipid membranes was characterized by biophysical methods. While the peptide binds to the vesicles composed of both neutral and acidic lipids, the apparent affinity is significantly higher for the latter lipid class. The intervesicular lipid mixing assay suggests that the synthetic peptide is able to induce fusion of large unilamellar vesicles. Circular dichroism and Fourier-transform infrared spectroscopy show that while in an aqueous buffer the peptide exists in an essentially unordered conformation, binding to the membranes results in a conformational transition to a @-structure. These data indicate that the fragment identified on the a-subunit of PH-30 as a putative fusion peptide is indeed a good candidate for this role. However, in contrast to what has been proposed for some viral fusion peptides, the PH-30 fusion domain is highly unlikely to act as an insertional "sided" helix.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Membrane Interaction and Conformational Properties of the Putative Fusion Peptide of PH-30, a Protein Active in Sperm-Egg Fusion

Muga

Neugebauer²,

Hirama³

et al. 1994

Biochemistry

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“…Some antigenic determinants on the MBP molecules may have been used for the associations, which could be reflected as a lost capability of complexing with the antibody. Depending on the type of lipid, MBP-lipid associations increase for 5-30 min (30), which could explain the scarce labeling in the 20-and 40-min samples. Inside the cells, MBP may also be proteolytically destroyed, thus losing its antigenic determinants.…”

Section: Discussionmentioning

confidence: 91%

Myelin Basic Protein Induces Morphological Changes in the Endocrine Pancreas

Kolehmainen

Sormunen

1998

Pancreas

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To evaluate effects of circulating myelin basic protein (MBP) on the endocrine pancreas, we injected bovine MBP to Djungarian hamsters and studied the morphological changes induced by MBP and its immunocytochemical distribution by electron microscopy. After a treatment time of 5-40 min, some islets appeared severely damaged, especially at their peripheries and near the intraislet capillaries, while others showed minor or no changes. MBP-induced extracellular changes included partial disintegration of the collagen filament network surrounding the islet and the blood vessels. These changes correlated with the association of MBP with the collagen filament bundles and related structures. Intracellularly, the effect of MBP included formation of vacuoles, dilatation of rough ER and Golgi membranes, swelling and aggregation of mitochondria, and disruption of the membranes of part of the insulin and glucagon granules, as well as damage to some plasma membranes. In the damaged B cells, 16-62% of the insulin granules exhibited an enlarged pale core, compared to 1-2% in the control B cells. MBP was shown to associate with mitochondria and with various intracellular membranes in all islet cells. In the B cells, MBP was localized to the membranes of insulin granules, and it also associated with the cores of the granules. In the A cells, the association of MBP to the glucagon granules was mainly with the outsides of the membranes. Interaction of MBP with the secretion granules is suggested to play a role in MBP-induced insulin and glucagon release, and some hormone might be released by leakage. Association of MBP with mitochondria, Golgi structures, and ER may lead to changes in various cellular functions. Key Words: Electron microscopyInsulin granule-Islet of Langerhans-Membrane fusionMitochondria-Myelin basic protein.Myelin basic protein (MBP) is one of the most abundant proteins in the central nervous system (CNS) and accounts for approximately one-third of the total myelin protein. In most mammals the major form is the 18.5-kDa MBP, one of several MBP variants (1). A proposed role for MBP is the maintenance of the multilamellar structure of the myelin sheath by joining the opposite cytoplasmic faces of the membrane.MBP is able to aggregate and fuse lipid vesicles of various compositions by ionic or hydrophobic interactions and to release their contents in vitro (2). MBP also associates with itself and with other proteins (2) including intracellular proteins such as calmodulin (3) and actin (4). MBP-induced morphological changes in vitro in chicken erythrocytes (5) and functional changes in hu-

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Interactions of myelin basic protein with palmitoyllysophosphatidylcholine: characterization of the complexes and conformations of the protein

1995

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The stoichiometry of palmitoyllysophosphatidylcholine/myelin basic protein (PLPC/MBP) complexes, the location of the protein in the lysolipid micelles, and the conformational changes occurring in the basic protein and peptides derived from it upon interaction with lysolecithin micelles were investigated by circular dichroic spectropolarimetry, ultracentrifugation, electron paramagnetic resonance (EPR) and 31P, 13C, and 1H nuclear magnetic resonance spectroscopy (NMR), and electron magnetic resonance spectroscopy (NMR), and electron microscopy. Ultracentrifugation measurements indicated that well-defined complexes were formed by the association of one protein molecule with approximately 141 lysolipid molecules. Small-angle X-ray scattering data indicated that the PLPC/MBP complexes form particles with a radius of gyration of 3.8 nm. EPR spectral parameters of the spin labels 5-, and 16-doxylstearate incorporated into lysolecithin/basic protein aggregates, and 13C- and 1H-NMR relaxation times of PLPC indicated that the addition of the protein did not affect the environment and location of the labels and the organization of the lysolipid micelles. The data suggested that MBP lies primarily near the surface of the micelles, with segments penetrating beyond the interfacial region into the hydrophobic interior, but without any part of the protein being protected against rapid exchange of its amide groups with the aqueous environment. The basic protein acquired about 20% alpha-helix when bound to lysolipid micelles. Circular dichroic spectra of sequential peptides derived by cleavage of the protein revealed the formation of alpha-helical regions in the association with lysolecithin. Specific residues in myelin basic protein that participated in binding to the micelles were identified from magnetic resonance data on changes in the chemical shifts and intensities of assigned resonances, and line broadening of peaks by fatty acid spin-labels incorporated into the micelles.

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Aliphatic aldehydes promote myelin basic protein-induced fusion of phospholipid vesicles

Cited by 7 publications

References 26 publications

Membrane Interaction and Conformational Properties of the Putative Fusion Peptide of PH-30, a Protein Active in Sperm-Egg Fusion

Membrane Interaction and Conformational Properties of the Putative Fusion Peptide of PH-30, a Protein Active in Sperm-Egg Fusion

Myelin Basic Protein Induces Morphological Changes in the Endocrine Pancreas

Interactions of myelin basic protein with palmitoyllysophosphatidylcholine: characterization of the complexes and conformations of the protein

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