Force Measurements on Myelin Basic Protein Adsorbed to Mica and Lipid Bilayer Surfaces Done with the Atomic Force Microscope

Mueller, Henning; Butt, Hans‐Jürgen; Bamberg, Ernst

doi:10.1016/s0006-3495(99)77272-3

Cited by 83 publications

(78 citation statements)

References 68 publications

(73 reference statements)

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“…On mica, force-versus-distance measurements showed that MBP behaves like a randomly coiled polymer. 36 MBP on lipid bilayers showed a completely different behavior. Thus the lipid bilayer must exhibit some property that allows MBP to adsorb and refold.…”

Section: Resultsmentioning

confidence: 95%

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Adsorption of Membrane-Associated Proteins to Lipid Bilayers Studied with an Atomic Force Microscope: Myelin Basic Protein and Cytochrome c

2000

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Atomic force microscopy was used to study the structure of two membrane-associated proteins adsorbed to various supported phospholipid bilayers in physiological buffer. The aim was (a) to develop a preparation for the investigation of membrane-associated proteins at high resolution under native conditions and (b) to obtain information about the factors that determine the adsorption process and the structure of adsorbed proteins. Therefore, solid-supported membranes were formed on mica by spontaneous vesicle adsorption and spreading. Once a homogeneous, pinhole-free bilayer was formed, solutions containing the proteins at appropriate concentrations were applied. The two positively charged proteins chosen were myelin basic protein (MBP), which plays an essential role in the formation of functional myelin, and cytochrome c. On charged bilayers, MBP applied at concentrations of 0.5-50 µg/mL formed aggregates of defined height (1.9 ( 0.2 nm on negatively and 2.7 ( 0.2 nm on positively charged lipids), which at high concentration covered the entire bilayer. These aggregates are probably monomolecular layers of MBP. On neutral lipid adsorbed MBP formed irregular aggregates. Cytochrome c showed a different adsorption: On negatively charged lipid it formed aggregates of defined, monomolecular height (3.3 ( 0.2 nm). On neutral bilayers small aggregates were observed. On positively charged lipid no adsorption was observed at all. These results indicate that (a) the adsorption of cytomchrome c can be interpreted in terms of a dominating electrostatic interaction; (b) MBP adsorption to lipid bilayers is not exclusively electrostatically driven and depends on the specific lipid bilayer composition; (c) the structure of adsorbed aggregates indicates a strong protein-protein interaction.

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Section: Resultsmentioning

confidence: 95%

“…Force curves of MBP-covered lipid bilayers have been reported earlier. 36 A major caveat in that work was that images of MBP adsorbed to the bilayer could not be obtained. Here we report on spatially resolved force spectroscopy by carrying out force scans on bare lipid bilayer and on MBP aggregates during the same experiment.…”

Section: Resultsmentioning

confidence: 97%

Adsorption of Membrane-Associated Proteins to Lipid Bilayers Studied with an Atomic Force Microscope: Myelin Basic Protein and Cytochrome c

2000

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“…There are several reports about force curves taken between protein layers [488][489][490][491] or on biological membranes [466,492,493]. In most cases no short-range repulsive forces could unambiguously be identified.…”

Section: Hydration Repulsionmentioning

confidence: 99%

Force measurements with the atomic force microscope: Technique, interpretation and applications

Butt

Cappella

Kappl

2005

Surface Science Reports

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“…The predominant size and charge isoform of MBP in healthy and mature myelin has a molecular weight of 18.5 kDa and a net positive charge of 19 (12, 13). Several studies conducted with model and extracted myelin bilayers (9,(14)(15)(16)(17)(18)(19) showed that because of its high content of positively charged residues, MBP binds to the negatively charged lipids of the cytoplasmic leaflets of the bilayer via electrostatic interaction in addition to hydrophobic interactions. However, studies have shown that the MBP charge component composition, as well as the balance between charged lipids and MBP charge components, changes in EAE (as well as in MS) tissues (20,21).…”

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confidence: 99%

Lipid domains control myelin basic protein adsorption and membrane interactions between model myelin lipid bilayers

Lee

Banquy

Kristiansen

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The surface forces apparatus and atomic force microscope were used to study the effects of lipid composition and concentrations of myelin basic protein (MBP) on the structure of model lipid bilayers, as well as the interaction forces and adhesion between them. The lipid bilayers had a lipid composition characteristic of the cytoplasmic leaflets of myelin from "normal" (healthy) and "disease-like" [experimental allergic encephalomyelitis (EAE)] animals. They showed significant differences in the adsorption mechanism of MBP. MBP adsorbs on normal bilayers to form a compact film (3-4 nm) with strong intermembrane adhesion (∼0.36 mJ/m 2 ), in contrast to its formation of thicker (7-8 nm) swelled films with weaker intermembrane adhesion (∼0.13 mJ/m 2 ) on EAE bilayers. MBP preferentially adsorbs to liquid-disordered submicron domains within the lipid membranes, attributed to hydrophobic attractions. These results show a direct connection between the lipid composition of membranes and membrane-protein adsorption mechanisms that affects intermembrane spacing and adhesion and has direct implications for demyelinating diseases.lipid raft | biomembrane adhesion | myelin structure | multiple sclerosis | intrinsically unstructured proteins M yelin is an asymmetric multilamellar membrane wrapped around the axons of the central nervous system (CNS) and consists of alternating extracellular and cytoplasmic leaflets (1-3). The bilayer-associated proteins, mainly myelin basic protein (MBP) and proteolipid protein, play an essential role in stabilizing and maintaining the myelin structure. The bilayers are in close contact (∼3 nm separation between lipid headgroupwater interfaces), providing a low dielectric constant through the compact bilayers, which is essential for efficient and fast saltatory propagation of nerve impulses. Any structural changes of the myelin sheath in the CNS, including lesion formation, loss of adhesion, swelling of the water gaps, vacuolization, vesiculation, and complete delamination (demyelination) of the myelin sheath (4-6), are signatures of several inflammatory neurological disorders. These types of disorders are characterized by a broad spectrum of neurological symptoms, such as physical and cognitive disabilities, with multiple sclerosis (MS) being one of the most common demyelinating diseases (2).The primary cause of structural changes in the myelin is still under debate; however, morphological changes of the myelin structure due to diseases such as MS are well known. A wellstudied and accepted animal model for MS is the experimental allergic encephalomyelitis (EAE) of the marmoset (2, 6). Using this model, recent studies conducted with the surface forces apparatus (SFA) have shown that a loss of adhesion force (7) and structural changes of model membranes with lipid composition characteristic of myelin accompanied compositional alterations of the lipid species (8), as well as an electric charge imbalance between lipid molecules and MBP (9). These alterations also change the lateral distribution a...

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Force Measurements on Myelin Basic Protein Adsorbed to Mica and Lipid Bilayer Surfaces Done with the Atomic Force Microscope

Cited by 83 publications

References 68 publications

Adsorption of Membrane-Associated Proteins to Lipid Bilayers Studied with an Atomic Force Microscope: Myelin Basic Protein and Cytochrome c

Adsorption of Membrane-Associated Proteins to Lipid Bilayers Studied with an Atomic Force Microscope: Myelin Basic Protein and Cytochrome c

Force measurements with the atomic force microscope: Technique, interpretation and applications

Lipid domains control myelin basic protein adsorption and membrane interactions between model myelin lipid bilayers

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