Penetration of the signal sequence of Escherichia coli PhoE protein into phospholipid model membranes leads to lipid-specific changes in signal peptide structure and alterations of lipid organization
In order to obtain more insight in the initial steps of the process of protein translocation across membranes, biophysical investigations were undertaken on the lipid specificity and structural consequences of penetration of the PhoE signal peptide into lipid model membranes and on the conformation of the signal peptide adopted upon interaction with the lipids. When the monolayer technique and differential scanning calorimetry are used, a stronger penetration is observed for negatively charged lipids, significantly influenced by the physical state of the lipid but not by temperature or acyl chain unsaturation as such. Although the interaction is principally electrostatic, as indicated also by the strong penetration of N-terminal fragments into negatively charged lipid monolayers, the effect of ionic strength suggests an additional hydrophobic component. Most interestingly with regard to the mechanism of protein translocation, the molecular area of the peptide in the monolayer also shows lipid specificity: the area in the presence of PC is consistent with a looped helical orientation, whereas in the presence of cardiolipin a time-dependent conformational change is observed, most likely leading from a looped to a stretched orientation with the N-terminus directed toward the water. This is in line also with the determined peptide-lipid stoichiometry. Preliminary /sup 31/P NMR and electron microscopy data on the interaction with lipid bilayer systems indicate loss of bilayer structure.
- Research Organization:
- State Univ. of Utrecht (Netherlands)
- OSTI ID:
- 6901557
- Journal Information:
- Biochemistry; (United States), Vol. 27:15
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MEMBRANE TRANSPORT
BIOCHEMICAL REACTION KINETICS
PROTEINS
NUCLEAR MAGNETIC RESONANCE
ELECTRON MICROSCOPY
ESCHERICHIA COLI
MEMBRANES
PHOSPHOLIPIDS
PHOSPHORUS 31
STOICHIOMETRY
BACTERIA
ESTERS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIPIDS
MAGNETIC RESONANCE
MICROORGANISMS
MICROSCOPY
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
REACTION KINETICS
RESONANCE
STABLE ISOTOPES
550601* - Medicine- Unsealed Radionuclides in Diagnostics