Abscisic acid promotes fusion of phospholipid vesicles

The plant hormone abscisic acid (ABA) is shown to promote the fusion of phospholipid small unilamellar vesicles under compositional and pH conditions similar to those previously reported for ABA-induced enhancement of membrane permeability and lipid vesicle aggregation. Single component phosphatidyl...

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Bibliographic Details
Published in:	Phytochemistry (Oxford) 1991, Vol.30 (11), p.3539-3544
Main Authors:	Stillwell, William, Brengle, Blair, Yu, Fong Cheng, Wassall, Stephen R.
Format:	Article
Language:	eng
Subjects:	8-aminonaphthalene-1,3, 6-trisulphonic acid ABA Abscisic acid ANTS Artificial membranes and reconstituted systems binding Biological and medical sciences cell membranes dilauroylphosphatidylethanolamine dimyristoylphosphatidylcholine dimyristoylphosphatidylethanolamine dioleoylphosphatidylcholine distearoylphosphatidylcholine DLPE DMPC DMPE DOPC DPX DSPC enhancement Fundamental and applied biological sciences. Psychology fusion lipid composition lissamine rhodamine-B-sulfonyl dioleoylphosphatidylethanolamine membrane fusion Membrane physicochemistry membranes Molecular biophysics p-xylene-bis-pyridinium bromide permeability phosphatidylcholine phosphatidylethanolamine phospholipid bilayers phospholipids plant physiology regulation resonance energy transfer NBD-PE N-4-nitrobenzo-2-oxa-1,3-diazole phosphatidylethanolamine RET Rho-PE vesicles
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Summary:	The plant hormone abscisic acid (ABA) is shown to promote the fusion of phospholipid small unilamellar vesicles under compositional and pH conditions similar to those previously reported for ABA-induced enhancement of membrane permeability and lipid vesicle aggregation. Single component phosphatidylcholine (PC) vesicles were resistant to ABA-induced fusion. Upon the incorporation of 10 membrane mol per cent phosphatidylethanolamine (PE) to the PC membranes the vesicles were shown to fuse as followed by two different techniques, one monitoring the intermixing of the membranes (florescence resonance energy transfer) and the other the mixing of the sequestered aqueous compartments. Both synthetic saturated and natural unsaturated phospholipids were tested. Fusion was dependent on the concentration of the minor (PE) membrane component as well as on the concentration of ABA. Membranes made of PC's having different acyl chains in which liquid crystal and gel states coexist, were also fused by ABA. The process was pH dependent as only non-dissociated hormone promoted fusion. Fusion is also shown to be inhibited by incorporation of plant sterols into the bilayers. Some selectivity was evident as the biologically active cis-trans geometric isomer of ABA was fusogenic while the biologically inactive trans-trans isomer was not. These experiments are consistent with a lipid site of action on membranes for ABA.
ISSN:	0031-9422 1873-3700