Localization of chromatophore proteins of Rhodobacter sphaeroides. I. Rapid Ca(2+)-induced fusion of chromatophores with phosphatidylglycerol liposomes for proteinase delivery to the luminal membrane surface
A protease delivery system was developed for the exclusive and controlled digestion of proteins exposed at the morphological inside (periplasmic surface) of Rhodobacter sphaeroides chromatophores. In this procedure, proteinase K is encapsulated within large unilamellar liposomes which are fused to t...
Gespeichert in:
Veröffentlicht in: | The Journal of biological chemistry 1991-12, Vol.266 (34), p.23157-23162 |
---|---|
Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | A protease delivery system was developed for the exclusive and controlled digestion of proteins exposed at the morphological
inside (periplasmic surface) of Rhodobacter sphaeroides chromatophores. In this procedure, proteinase K is encapsulated within
large unilamellar liposomes which are fused to the chromatophores in the presence of Ca2+ ions. The liposomes were prepared
by a detergent dialysis procedure from native phosphatidylglycerol and found to undergo rapid bilayer fusion with purified
chromatophore preparations above a threshold concentration of 12.5 mM CaCl2. The fusion process was complete within 10 min
at 35 mM Ca2+ with about 80% of the pigment located in the fusion products. Electron micrographs of freeze-fracture replicas
confirmed the intermixing of the lipid bilayers and the unilamellar structure of the fused membrane vesicles. The procedure
did not affect the labile B800 chromophore of the B800-850 antenna complex, but reduced slightly the absorption due to the
B875 core antenna. Emission from both light-harvesting complexes was increased in the fused membranes, suggesting a partial
dissociation of photosynthetic units in the expanded bilayer. The results, together with those presented in the following
paper (Theiler, R., and Niederman, R. A. (1991) J. Biol. Chem. 266, 23163-23168), demonstrate that this new method fulfills
the stringent requirements for a successful delivery of macromolecules to the chromatophore interior. |
---|---|
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(18)54477-X |