ISSN:1075-2617    

DOI:10.1002/psc.1013

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractWe describe a new approach to calculate the binding of flexible peptides and unfolded proteins to multicomponent lipid membranes. The method is based on the transfer matrix formalism of statistical mechanics recently described as a systematic tool to study DNA–protein–drug binding in gene regulation. Using the energies of interaction of the individual polymer segments with different membrane lipid species and the scaling corrections due to polymer looping, we calculate polymer adsorption characteristics and the degree of sequestration of specific membrane lipids. The method is applied to the effector domain of the MARCKS (myristoylated alanine rich C kinase substrate) protein known to be involved in signal transduction through membrane binding. The calculated binding constants of the MARCKS(151–175) peptide and a series of related peptides to mixed PC/PS/PIP2 membranes are in satisfactory agreement within vitroexperiments. Copyright © 2008 European Peptide Society and John Wiley&Son

ISSN:1075-2617    

DOI:10.1002/psc.994

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractA molecular dynamics simulation study of four lipid bilayers with inserted trans‐membrane helical fragment of epithelial growth factor (EGF) receptor (EGF peptide) was performed. The lipid bilayers differ in their lipid composition and consist of (i) unsaturated phosphatidylcholine (palmitoyloleoylphosphatidylcholine, POPC), (ii) POPC and 20 mol% of cholesterol (Chol), (iii) sphingomyelin (SM) and 20 mol% of Chol, and (iv) SM and 50 mol% of Chol. Only 1 out of 26 residues in the EGF‐peptide sequence is polar (Thr). The hydrophobic thickness of each bilayer is different but shorter than the length of the peptide and so, due to hydrophobic mismatch, the inserted peptide is tilted in each bilayer. Additionally, in the POPC bilayer, which is the thinnest, the peptide loses its helical structure in a short three‐amino acid fragment. This facilitates bending of the peptide and burying all hydrophobic amino acids inside the membrane core (Figure 1(b)). Bilayer lipid composition affects interactions between the peptide and lipids in the membrane core. Chol increases packing of atoms relative to the peptide side chains, and thus increases van der Waals interactions. On average, the packing around the peptide is higher in SM‐based bilayers than POPC‐based bilayers but for certain amino acids, packing depends on their position relative to the bilayer center. In the bilayer center, packing is higher in POPC‐based bilayers, while in regions closer to the interface packing is higher in SM‐based bilayers. In general, amino acids with larger side chains interact strongly with lipids, and thus the peptide sequence is important for the pattern of interactions at different membrane depths. This pattern closely resembles the shape of recently published lateral pressure profiles [Ollilaet alJ. Struct. Biol. DOI:10.1016/j.jsb.2007.01.012]. Copyright © 2007 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/psc.936

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe V‐ATPases are ATP‐dependent proton pumps, found in virtually all cells, responsible for acidification of organelles and energizing of plasma membranes. Its role in diseases, such as osteoporosis and metastatic cancer, makes the V‐ATPase a potential drug target. Short synthetic peptides that are presented here mimic the 7th transmembrane domain (TM7) of subunita(Vph1p) ofSaccharomyces cerevisiaeV‐ATPase, an essential part of the membrane‐bound VOdomain, where proton translocation takes place. The peptides adopt a transmembrane configuration only in membranes containing anionic lipids, stressing the importance of strong interfacial anchoring by the flanking lysines. Peptide P1, which contains the essential arginine R735, is monomeric, whereas peptide P2, which lacks this extra charge, tends to aggregate in the membrane. SB 242784, which is a highly potent inhibitor of V‐ATPase, does not show any interaction with the peptides, indicating that TM7 alone is not sufficient for inhibitor binding. Copyright © 2007 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.980

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractTwo transmembrane peptides encompassing the seventh transmembrane section of subunitafrom V‐ATPase fromSaccharomyces cerevisiaewere studied as complexes with APols A8‐35 by CD and fluorescence spectroscopy, with the goal to use APols to provide a membrane‐mimicking environment for the peptides. CD spectroscopy was used to obtain the overall secondary structure of the peptides, whereas fluorescence spectroscopy provided information about the local environment of their tryptophan residues. The fluorescence results indicate that both peptides are trapped by APols and the CD results that they adopt a β‐sheet conformation. This result is in contrast with previous work that showed that the same peptides are α‐helical in SDS micelles and organic solvents. These observations are discussed in the context of APol physical–chemical properties and transmembrane peptide structural propensity. Copyright © 2007 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/psc.996

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractHighly charged peptides are important components of the immune system and belong to an important family of antibiotics. Although their therapeutic activity is known, most of the molecular level mechanisms are controversial. A wide variety of different approaches are usually applied to understand their mechanisms, but light scattering techniques are frequently overlooked. Yet, light scattering is a noninvasive technique that allows insights both on the peptide mechanism of action as well as on the development of new antibiotics. Dynamic light scattering (DLS) and static light scattering (SLS) are used to measure the aggregation process of lipid vesicles upon addition of peptides and molecular properties (shape, molecular weight). The high charge of these peptides allows electrostatic attraction toward charged lipid vesicles, which is studied by zeta potential (ζ‐potential) measurements. Copyright © 2008 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/psc.1007

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractProtein–protein interactions, as well as peptide–peptide and peptide–protein interactions are fields of study of growing importance as molecular‐level detail is avidly pursued in drug design, metabolic regulation and molecular dynamics, among other classes of studies. In membranes, this issue is particularly relevant because lipid bilayers potentiate molecular interactions due to the high local concentration of peptides and other solutes.However, experimental techniques and methodologies to detect and quantify such interactions are not abundant. A reliable, fast and inexpensive alternative methodology is revisited in this work.Considering the interaction of two molecules, at least one of them being fluorescent, either intrinsically (e.g. Trp residues) or by grafting a specific probe, changes in their aggregation state may be reported, as long as the fluorophore is sensitive to local changes in polarity, conformation and/or exposure to the solvent. The interaction will probably lead to modifications in fluorescence intensity resulting in a decrease (‘quenching’) or enhancement (‘dequenching’). Although the presented methodology is based on static quenching methodologies, the concept is extended from quenching to any kind of interference with the fluorophore.Equations for data analysis are shown and their applications are illustrated by calculating the binding constant for several data‐sets. Copyright © 2007 European Peptide Society and Jo

ISSN:1075-2617    

DOI:10.1002/psc.939

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractPeptide–membrane interaction is an important step to be evaluated in a study of the activity and mode of action of several bioactive peptides. A variety of methods are available; however, few of them satisfy the criteria of being sensitive, biocompatible, versatile, easy to perform, and allowing real‐time monitoring as the use of potential‐sensitive fluorescent probes. Here we review methods for detecting the effects of membrane‐active peptides, even those that are not intrinsically fluorescent, on the different types of membrane potentials, with a special emphasis on studies conducted with living cells. FPE is a probe sensitive to surface potential and detects electrostatic interactions at the water‐lipid interface. Di‐8‐ANEPPS is sensitive to dipole potential and detects membrane incorporations. Transmembrane potential changes reveal major membrane destabilizations, such as in pore formation. The combination of the information obtained from the three potential variations can lead to a more elucidative picture of the mechanisms of the interaction of relevant peptides with biomembranes. Copyright © 2008 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/psc.1005

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractTilted peptides are short hydrophobic protein fragments characterized by an asymmetric distribution of their hydrophobic residues when helical. They are able to interact with a hydrophobic/hydrophilic interface (such as a lipid membrane) and to destabilize the organized system into which they insert. They were detected in viral fusion proteins and in proteins involved in different biological processes involving membrane insertion or translocation of the protein in which they are found. In this paper, we have analysed different protein domains related to membrane insertion with regard to their tilted properties. They are theN‐terminal signal peptide of the filamentous haemagglutinin (FHA), aBordetella pertussisprotein secreted in high amount and the hydrophobic domain from proteins forming pores (i.e. ColIa, Bax and Bcl‐2). From the predictions and the experimental approaches, we suggest that tilted peptides found in those proteins could have a more general role in the mechanism of insertion/translocation of proteins into/across membranes. For the signal sequences, they could help the protein machinery involved in protein secretion to be more active. In the case of toroidal pore formation, they could disturb the lipids, facilitating the insertion of the other more hydrophilic helices. Copyright © 2007 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/psc.971

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractWe had previously predicted successfully the minimal fusion peptides (FPs) of the human immunodeficiency virus 1 (HIV‐1) gp41 and the bovine leukemia virus (BLV) gp30 using an original approach based on the obliquity/fusogenicity relationship of tilted peptides. In this paper, we have used the same method to predict the shortest FP capable of inducing optimal fusionin vitroof the simian immunodeficiency virus (SIV) mac isolate and of other SIVs and human immunodeficiency virus (HIV‐2) isolates. In each case, the 11‐residue‐long peptide was predicted as the minimal FP. For the SIV mac isolate, liposome lipid‐mixing and leakage assays confirmed that this peptide is the shortest peptide inducing optimal fusionin vitro, being therefore the minimal FP. These results are another piece of evidence that the tilted properties of FPs are important for the fusion process and that our method can be used to predict the minimal FPs of other viruses. Copyright © 2007 European Peptide Society and John Wiley

ISSN:1075-2617    

DOI:10.1002/psc.949

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY