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1.
Huet J Wyckmans J Wintjens R Boussard P Raussens V Vandenbussche G Ruysschaert JM Azarkan M Looze Y 《Cellular and molecular life sciences : CMLS》2006,63(24):3042-3054
Two chitinases, able to use tetra-N-acetylglucosamine, chitin and chitosan as substrates, were characterized after purification from Carica papaya latex. The complete amino acid sequence of the major form and about 40% of the minor one were determined through proteolytic
digestions and mass spectroscopy analysis. Sequencing demonstrated that both papaya chitinases are members of the family 19
of glycosyl hydrolases (GH19). Based on the known 3-D structures of other members of family GH19, it was expected that papaya
chitinases would adopt all-alpha structures. However, circular dichroism and infrared spectroscopy indicated, for the papaya
chitinases, a content of 15–20% of extended structures besides the expected 40% of alpha helices. Since the fully sequenced
papaya chitinase contains a large number of proline residues the possibility that papaya chitinase contains polyproline II
stretches was examined in the context of their resistance against proteolytic degradation.
Received 11 July 2006; received after revision 13 October 2006; accepted 25 October 2006 相似文献
2.
Gbaguidi B Mazurkiewicz P Konings WN Driessen AJ Ruysschaert JM Vigano C 《Cellular and molecular life sciences : CMLS》2004,61(19-20):2646-2657
LmrP from Lactococcus lactis is a 45-kDa membrane protein that confers resistance to a wide variety of lipophilic compounds by acting as a proton motive force-driven efflux pump. This study shows that both the proton motive force and ligand interaction alter the accessibility of cytosolic tryptophan residues to a hydrophilic quencher. The proton motive force mediates an increase of LmrP accessibility toward the external medium and results in higher drug binding. Residues Asp128 and Asp68, from cytosolic loops, are involved in the proton motive force-mediated accessibility change. Ligand binding does not modify the protein accessibility, but the proton motive force-mediated restructuring is prerequisite for a subsequent accessibility change mediated by ligand binding. Asp142 cooperates with other membrane-embedded carboxylic residues to promote a conformational change that increases LmrP accessibility toward the hydrophilic quencher. This drug binding-mediated reorganization may be related to the transition between the high- and low-affinity drug-binding sites and is crucial for drug release in the extracellular medium. 相似文献
3.
Activation of innate immunity by lysozyme fibrils is critically dependent on cross-β sheet structure
Adelin Gustot Vincent Raussens Morgane Dehousse Mireille Dumoulin Clare E. Bryant Jean-Marie Ruysschaert Caroline Lonez 《Cellular and molecular life sciences : CMLS》2013,70(16):2999-3012
Inflammation occurs in many amyloidoses, but its underlying mechanisms remain enigmatic. Here we show that amyloid fibrils of human lysozyme, which are associated with severe systemic amyloidoses, induce the secretion of pro-inflammatory cytokines through activation of the NLRP3 (NLR, pyrin domain containing 3) inflammasome and the Toll-like receptor 2, two innate immune receptors that may be involved in immune responses associated to amyloidoses. More importantly, our data clearly suggest that the induction of inflammatory responses by amyloid fibrils is linked to their intrinsic structure, because the monomeric form and a non-fibrillar type of lysozyme aggregates are both unable to trigger cytokine secretion. These lysozyme species lack the so-called cross-β structure, a characteristic structural motif common to all amyloid fibrils irrespective of their origin. Since fibrils of other bacterial and endogenous proteins have been shown to trigger immunological responses, our observations suggest that the cross-β structural signature might be recognized as a generic danger signal by the immune system. 相似文献
4.
Gbaguidi B Hakizimana P Vandenbussche G Ruysschaert JM 《Cellular and molecular life sciences : CMLS》2007,64(12):1571-1582
LmrP is an electrogenic H+/drug antiporter that extrudes a broad spectrum of antibiotics. Five carboxylic residues are implicated in drug binding (Asp142
and Glu327) and proton motive force-mediated restructuring (Asp68, Asp128 and Asp235). ATR-FTIR (Attenuated Total Reflection
– Fourier Transform Infrared) and tryptophan quenching experiments revealed that phosphatidylethanolamine (PE) is required
to generate the structural intermediates induced by ionization of carboxylic residues. Surprisingly, no ionization-induced
conformational changes were detectable in the absence of PE, suggesting either that carboxylic acid residues do not ionize
or that ionization does not lead to any conformational change. The mean pKa of carboxylic residues evaluated by ATR-FTIR spectroscopy
was 6.5 for LmrP reconstituted in PE liposomes, whereas the pKa calculated in the absence of PE was 4.6. Considering that
16 of the 19 carboxylic residues are located in the extramembrane loops, the pKa values obtained in the absence and in the
presence of PE suggest that the interaction of the loop acid residues with the membrane interface depends on the lipid composition.
Received 23 January 2007; received after revision 2 April 2007; accepted 20 April 2007 相似文献
5.
6.
M. Vandenbranden C. Stil R. Brasseur J. -M. Ruysschaert 《Cellular and molecular life sciences : CMLS》1984,40(7):715-717
Summary The evolution of the thermotropic properties of large unilamellar vesicles (LUV) made by the reverse-phase evaporation technique has been studied by differential scanning calorimetry (DSC) and by fluorescence polarization of the diphenylhexatriene probe inserted in the lipid phase. Lipid fluidity and transition temperatures of DL-a-dimyristoyl-and DL-a-dipalmitoyl-phosphatidylcholine vesicles were practically not modified at room temperature (19–20°C), even after several days. Because a better knowledge of the physico-chemical properties of LUV seems essential for its use as a model membrane or as a carrier of exogenous material into cells, we compare it with the stability of the widely used multilamellar (MLV) and sonicated unilamellar vesicles (SUV). 相似文献
7.
Caroline Lonez Marc F. Lensink Emilie Kleiren Jean-Marie Vanderwinden Jean-Marie Ruysschaert Michel Vandenbranden 《Cellular and molecular life sciences : CMLS》2010,67(3):483-494
Addition of co-lipids into cationic lipid formulations is considered as promoting cell delivery of DNA by enhancing fusion
processes with cell membranes. Here, by combining FRET and confocal microscopy, we demonstrate that some cationic lipids do
not require a co-lipid to fuse efficiently with cells. These cationic lipids are able to self-organize into bilayers that
are stable enough to form liposomes, while presenting some destabilizing properties reminiscent of the conically shaped fusogenic
co-lipid, DOPE. We therefore analyzed the resident lipid structures in cationic bilayers by molecular dynamics simulations,
clustering the individual lipid structures into populations of similarly shaped molecules, as opposed to the classical approach
of using the static packing parameter to define the lipid shapes. Comparison of fusogenic properties with these lipid populations
suggests that the ratio of cylindrical versus conical lipid populations correlates with the ability to fuse with cell membranes. 相似文献
8.
Lonez C Legat A Vandenbranden M Ruysschaert JM 《Cellular and molecular life sciences : CMLS》2008,65(4):620-630
The inflammatory effect of unmethylated CpG DNA sequences represents a major obstacle to the use of cationic lipids for in vivo gene therapy. Although the mechanism of CpG-induced inflammatory response is rather well understood nowadays, few solutions
have been designed to circumvent this effect in gene therapy experiments. Our previous work has shown that a refractory state
towards inflammation can be elicited by preinjecting cationic liposomes. Here, we present evidence that diC14-amidine liposomes
confer new anti-inflammatory properties to phospholipids from low-density lipoprotein (LDL) and even to synthetic phospholipids
for which such an observation has not been reported so far. Whereas oxidation of LDL lipids was a prerequisite for any anti-inflammatory
activity, lipid oxidation is no longer required in our experiments, suggesting that cationic lipids transport phospholipids
through a different route and affect different pathways.This opens up new possibilities for manipulating inflammatory responses
in gene therapy protocols but also in a general manner in immunological experiments.
Received 12 November 2007; received after revision 4 December 2007; accepted 4 December 2007 相似文献
9.
P. Chatelain M. Deleers A. Poss J. M. Ruysschaert 《Cellular and molecular life sciences : CMLS》1979,35(3):334-335
Summary A specific interaction was demonstrated between GT1 gangliosides incorporated in bilayer membranes and luteinizing hormone. This interaction would allow the penetration of a hormone subunit in the membrane. The results are discussed in terms of adenylate cyclase activation. 相似文献
10.
S. P. Dufrane A. Poss E. Goormaghtigh J. M. Ruysschaert 《Cellular and molecular life sciences : CMLS》1981,37(5):524-525
Summary We present evidence that cholesterol mediates thyrotropin binding to liposomes containing GT1 ganglioside. Thyrotropin fixation is maximal at 22% of cholesterol. This result suggests that the gangliosides' organization in the lipid matrix modulates their interaction with the glycoprotein hormone. 相似文献