This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Marvin, H J Articles by Witholt, B Search for Related Content PubMed PubMed Citation Articles by Marvin, H J Articles by Witholt, B

research-article

Fusion of small unilamellar vesicles with viable EDTA-treated Escherichia coli cells.

Department of Biochemistry, University of Groningen, The Netherlands.

ABSTRACT

Fusion characteristics of EDTA-treated Escherichia coli cells with small unilamellar vesicles were investigated, using a membrane fusion assay based on resonance energy transfer. Ca2+-EDTA treatments of Escherichia coli O111:B4 (wild type), E. coli C600 (rough), and E. coli D21f2 (deep rough) which permeabilize the outer membrane by inducing the release of lipopolysaccharide and outer membrane proteins resulted in fusion activity of the intact and viable bacteria with small unilamellar vesicles. No fusion activity was observed when the EDTA treatment was omitted. Fusion could be elicited at low pH and by a combination of a higher pH and Ca2+. The low-pH-induced fusion was composed of a fast and a slow reaction. The latter and the Ca2+-induced fusion could be completely inhibited by trypsin treatments of the EDTA-treated cells, which also resulted in the simultaneous disappearance of two outer membrane protein bands (50 and 58 kilodaltons) and the appearance of proteins banding at 22, 52, and 54 kilodaltons. The most efficient fusion was obtained with negatively charged liposomes composed of cardiolipin. In contrast to the Ca2+-induced fusion, fusion was observed at low pH with small unilamellar vesicles containing lipids with decreased negative charge (phosphatidylserine). Fluorescent and phase-contrast microscopy revealed that essentially all bacteria were engaged in fusion. We propose that a Ca2+-EDTA treatment of E. coli cells results in the appearance of phospholipids and the exposure of a protein(s) in the outer leaflet of the outer membrane, both of which could mediate fusion with liposomes.

This article has been cited by other articles:

• Daugelavicius, R., Cvirkaite, V., Gaidelyte, A., Bakiene, E., Gabrenaite-Verkhovskaya, R., Bamford, D. H. (2005). Penetration of Enveloped Double-Stranded RNA Bacteriophages {phi}13 and {phi}6 into Pseudomonas syringae Cells. J. Virol. 79: 5017-5026 [Abstract] [Full Text]