Biophysical studies of membrane proteins/peptides. Interaction with ...

More documents

Recommendations

Info

the vesicle through bilayer deformation in the interface and to the insertion of phospholipids in the interface region with intermediate conformations (between gel and fluid like conformations) in order to substantially decrease the interface stress between lipid domains (Jorgensen and Mouritsen, 1995). Another possibility is that the finite size domains correspond to non-equilibrium structures, detected due to the very long lifetime of the process of phase separation (de Almeida et al., 2002). Even when at the same lamellar phase, lipids do not mix ideally. This is particularly true for the gel phase, as the strict packing restrictions force dissimilar lipids to immiscibility. As a result, clustering or domain formation is observed and the bilayer gains lateral heterogeneity. This type of behaviour is observed e.g. for the highly nonideal mixture DLPC-DSPC (Fig. I.7), as two different gel phases (each enriched in one of the lipids) are present below the phase coexistence region. Deviations from ideal lipid mixing and domain formation also occur in the fluid phase, and PC lipids with a significantly different thickness were already shown to segregate into domains due to hydrophobic mismatch stress. Also for this situation, the discrepancy of hydrophobic thickness of the two PC lipids can create a packing stress in the bilayer due to exposure of hydrocarbons to water, and stimulate lipid segregation (Lehtonen et al., 1996). The lateral structures created by this type of phase separation are expected to be on the nanometer scale in opposition to gel-fluid phase separation which can be detected in the micrometer scale. Therefore, these domains are elusive to most of the imaging techniques, and other spectroscopic techniques must be applied, namely macroscopic fluorescence methodologies. The ideality degree of a lipid mixture dictates not only the phase separation of the mixture but also the size and shape of the phase-separated domains. Apart from temperature, other factors influencing the lateral structuring of a multicomponent lipid bilayer are dehydration and the presence of divalent ions. Dehydration can cause lamellar to inverted hexagonal phase transition and induce phase separation (Webb et al., 1993). Mixtures containing an anionic phospholipid can experience severe phase separation in the presence of divalent ions like Ca 2+ . Calcium ions induce clustering and phase separation of anionic phospholipids due to intermolecular cross bridges (Silvius, 1990). A phase coexistence of particular biological relevance is that of L α and L o phases. In 1997 Simons and Ikonen proposed that small lipid domains in the L o phase (lipid rafts) composed of saturated lipids and cholesterol coexisted with a matrix of lipids in the 16
INTRODUCTION: BIOMEMBRANES fluid phase. Since then, several cellular mechanisms have been associated with domains of cholesterol and saturated lipids, and several evidences for the existence of these structures have been gathered. There is indication that rafts are involved in cell surface signalling, intracellular trafficking and sorting of lipids and proteins (Mouritsen, 2005) Lateral structuring of the lipid bilayer, either through L α -L β , L α -L o or fluid-fluid domains, implies that membrane functions do not require the dependence on random collisions for interactions between reagents (Mouritsen, 2005). It provides a structuring principle for lipid bilayer organization, that can permit not only a higher efficiency of several membrane processes by compartmentalization, but also a mechanism of modulating these processes through control of the membrane lateral structure. 1.8. Membrane proteins The lipid bilayer provides the basic architecture of the biomembranes. However, membrane proteins are responsible for the majority of cell functions taking place in the membrane. The distinctive properties and functions of different lipid membranes inside the cell are mainly dictated by their protein content. The concentration of proteins inside biomembranes is drastically different among the several cellular membranes. In the mitochondrial membrane the protein content reaches about 76% (w/w), while in the myelin membrane proteins are only 18% of total membrane content. The mapping of the yeast genome showed that most of the genome code is expected to code for membrane proteins, in demonstration of their key role for life (Mouritsen, 2005). Membrane proteins are defined by their degree of insertion in the lipid bilayer (Figure I.9). Thus, membrane proteins deeply buried in the lipid bilayer are called integral, frequently spanning the membrane one or several times, whereas proteins bound to the exoplasmic or cytoplasmic periphery of the lipid bilayer are entitled peripheral. Peripheral membrane proteins are bound to lipid bilayers by interaction either with lipid headgroups or with other membrane bound proteins. Another class of proteins are bound to the membrane through covalent linkage to a lipid molecule. These membrane proteins are classified as lipid-anchored. 17
Page 1: UNIVERSIDADE TÉCNICA DE LISBOA INS
Page 4 and 5: Fernandes, F., Loura, L. M. S., Fed
Page 6 and 7: Ao Pedro e Hugo, amigos de longa da
Page 8 and 9: 2.2. - Peptides as models 2.3. - Am
Page 11 and 12: ABBREVIATIONS AND SYMBOL LIST ABBRE
Page 13: RESUMO RESUMO As biomembranas são
Page 17 and 18: SINOPSE SINOPSE Nas últimas duas d
Page 19 and 20: SINOPSE podem fornecer informação
Page 21 and 22: SINOPSE aceitantes. Dadores mais pr
Page 23 and 24: OUTLINE OUTLINE The last two decade
Page 25 and 26: OUTLINE membranes with a distributi
Page 27: OUTLINE BAR domains (tubulation of
Page 30 and 31: ion diffusion, as the energy requir
Page 32 and 33: acid. If no more groups are linked
Page 34 and 35: sphingomyelin, the most abundant sp
Page 36 and 37: signal for neighbouring cells to ph
Page 38 and 39: functional role in process such as
Page 40 and 41: in the L α phase, while lateral di
Page 42 and 43: 1.7. Lateral heterogeneity in lipid
Page 46 and 47: Figure I.9 - Depiction of the sever
Page 48 and 49: Figure I.11 - Experimentally obtain
Page 50 and 51: drying into a film and ressuspensio
Page 52 and 53: deactivating agents. Zwitterionic d
Page 54 and 55: amphipatic helices (see Section 2.3
Page 56 and 57: size corresponding to the hydrophob
Page 58 and 59: changes abruptly in the interfacial
Page 60 and 61: thickness of the bilayer (Section 1
Page 62 and 63: some α-helical membrane proteins a
Page 64 and 65: The formation of a lipid population
Page 66 and 67: homogeneous distribution of lipids
Page 68 and 69: Figure I.20 - Relative binding cons
Page 70 and 71: 2.9. Lipid phase preferential parti
Page 72 and 73: In Figure I.21, theoretical simulat
Page 75 and 76: PROTEIN-PROTEIN AND PROTEIN-LIPID I
Page 77 and 78: PROTEIN-PROTEIN AND PROTEIN-LIPID I
Page 79: PROTEIN-PROTEIN AND PROTEIN-LIPID I
Page 83 and 84: 2430 Biophysical Journal Volume 85
Page 85 and 86: 2432 Fernandes et al. Coat protein
Page 87 and 88: 2434 Fernandes et al. leads to an a
Page 89 and 90: 2436 Fernandes et al. FIGURE 4 (A)
Page 91 and 92: 2438 Fernandes et al. section of th
Page 93 and 94: 2440 Fernandes et al. tein oligomer
Page 95:
QUANTIFICATION OF PROTEIN-LIPID SEL
Page 98 and 99:
FRET Study of Protein-Lipid Selecti
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 107 and 108:
BINDING OF INHIBITORS TO A PUTATIVE
Page 109 and 110:
BINDING OF INHIBITORS TO A PUTATIVE
Page 111:
INTERACTION OF THE INDOLE CLASS OF
Page 114 and 115:
5272 Biochemistry, Vol. 45, No. 16,
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 123:
BINDING ASSAYS OF INHIBITORS TOWARD
Page 126 and 127:
1778 F. Fernandes et al. / Biochimi
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
apparently the most significant as
Page 138 and 139:
110
Page 140 and 141:
Introduction Quinolones are broad-s
Page 142 and 143:
[9-12]. Having this into considerat
Page 144 and 145:
any case, very similar, probably wi
Page 146 and 147:
placement of the protein around the
Page 148 and 149:
⎛ II t ⎛ R ⎞ 0 ρ () t = exp
Page 150 and 151:
APPENDIX - Derivation of the FRET r
Page 152 and 153:
2 2w J ( t) = '2 R − R + w / 1
Page 154 and 155:
[14] L. Plançon, M. Chami, L. Lete
Page 156 and 157:
acceptors) (Eqs. 4-6) (⋅-⋅-⋅)
Page 158 and 159:
FIGURE 1A FIGURE 1B 130
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
136
Page 166 and 167:
dynamin. Soon after, the same group
Page 168 and 169:
140
Page 170 and 171:
142
Page 172 and 173:
Introduction Control of membrane re
Page 174 and 175:
Steady-state fluorescence measureme
Page 176 and 177:
Rho-DOPE (acceptor). The increase o
Page 178 and 179:
where η is the viscosity of the me
Page 180 and 181:
ound conformation of the BAR domain
Page 182 and 183:
19. Fernandes, F., L. M. S. Loura,
Page 184 and 185:
Figure Legends Fig.1: N-terminal am
Page 186 and 187:
FIG. 1A FIG.1B 17
Page 188 and 189:
FIG. 3A FIG. 3B 19
Page 190 and 191:
FIG.5A 21
Page 192 and 193:
FIG 6. 23
Page 194 and 195:
FIG. 8 A B 25
Page 196 and 197:
The signalling functions of PI(4,5)
Page 198 and 199:
172
Page 200 and 201:
174
Page 202 and 203:
zoxadiazol (NBD)-PC were obtained f
Page 204 and 205:
Fig. 3. Fluorescence decays of diph
Page 206 and 207:
CONCLUSIONS VII CONCLUSIONS Chapter
Page 208 and 209:
CONCLUSIONS constants recovered by
Page 210 and 211:
CONCLUSIONS Chapter IV ‐ Binding
Page 212 and 213:
CONCLUSIONS Chapter VI - Clustering
Page 214 and 215:
FINAL CONSIDERATIONS AND PROSPECTS
Page 216 and 217:
BIBLIOGRAPHY IX BIBLIOGRAPHY Albert
Page 218 and 219:
BIBLIOGRAPHY Phosphatidylinositol 4
Page 220 and 221:
BIBLIOGRAPHY Glaubitz, C., Grobner,
Page 222 and 223:
BIBLIOGRAPHY Koehorst, R. B. M., Sp
Page 224 and 225:
BIBLIOGRAPHY Mishra, V. K., Palguna
Page 226 and 227:
BIBLIOGRAPHY Pluschke, G., Hirota,
Page 228 and 229:
BIBLIOGRAPHY Sperotto, M. M., and M
Page 230:
BIBLIOGRAPHY Williamson, I. M., Alv
show all

Biophysical studies of membrane proteins/peptides. Interaction with ...

Create successful ePaper yourself

Delete template?

Save as template?