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Article: Combined interaction of phospholipase C and apolipoprotein A-I with small unilamellar lecithin-cholesterol vesicles: Influence of apolipoprotein A-I concentration and vesicle composition

TitleCombined interaction of phospholipase C and apolipoprotein A-I with small unilamellar lecithin-cholesterol vesicles: Influence of apolipoprotein A-I concentration and vesicle composition
Authors
KeywordsChemicals And Cas Registry Numbers
Issue Date2005
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/biochemistry
Citation
Biochemistry, 2005, v. 44 n. 19, p. 7294-7304 How to Cite?
AbstractWe report the combined effects of phospholipase C (PLC), a pronucleating factor, and apolipoprotein A-I (apo A-I), an antinucleating factor, in solutions of model bile. Results indicate that apo A-I inhibits cholesterol nucleation from unilamellar lecithin vesicles by two mechanisms. Initially, inhibition is achieved by apo A-I shielding of hydrophobic diacylglycerol (DAG) moieties so as to prevent vesicle aggregation. Protection via shielding is temporary. It is lost when the DAG/apo A-I molar ratio exceeds a critical value. Subsequently, apo A-I forms small (∼5-15 nm) complexes with lecithin and cholesterol that coexist with lipid-stabilized (400-800 nm) DAG oil droplets. This microstructural transition from vesicles to complexes avoids nucleation of cholesterol crystals and is a newly discovered mechanism by which apo A-I serves as an antinucleating agent in bile. The critical value at which a microstructural transition occurs depends on binding of apo A-I and so varies with the cholesterol mole fraction of vesicles. Aggregation of small, unilamellar, egg lecithin vesicles (SUVs) with varying cholesterol composition (0-60 mol %) was monitored for a range of apo A-I concentrations (2 to 89 μg/mL). Suppression of aggregation persists so long as the DAG-to-bound-apo A-I molar ratio is less than 100. A fluorescence assay involving dansylated lecithin shows that the suppression is an indirect effect of apo A-I rather than a direct inhibition of PLC enzyme activity. The DAG-to-total apo A-I molar ratio at which suppression is lost increases with cholesterol because of differences in apo A-I binding. Above this value, a microstructural transition to DAG droplets and lecithin/cholesterol A-I complexes occurs, as evidenced by sudden increases in turbidity and size and enhancement of Förster resonance energy transfer; structures are confirmed by cryo TEM. © 2005 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/92508
ISSN
2015 Impact Factor: 2.876
2015 SCImago Journal Rankings: 1.769
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorGudheti, MVen_HK
dc.contributor.authorLee, SPen_HK
dc.contributor.authorDanino, Den_HK
dc.contributor.authorWrenn, SPen_HK
dc.date.accessioned2010-09-17T10:48:23Z-
dc.date.available2010-09-17T10:48:23Z-
dc.date.issued2005en_HK
dc.identifier.citationBiochemistry, 2005, v. 44 n. 19, p. 7294-7304en_HK
dc.identifier.issn0006-2960en_HK
dc.identifier.urihttp://hdl.handle.net/10722/92508-
dc.description.abstractWe report the combined effects of phospholipase C (PLC), a pronucleating factor, and apolipoprotein A-I (apo A-I), an antinucleating factor, in solutions of model bile. Results indicate that apo A-I inhibits cholesterol nucleation from unilamellar lecithin vesicles by two mechanisms. Initially, inhibition is achieved by apo A-I shielding of hydrophobic diacylglycerol (DAG) moieties so as to prevent vesicle aggregation. Protection via shielding is temporary. It is lost when the DAG/apo A-I molar ratio exceeds a critical value. Subsequently, apo A-I forms small (∼5-15 nm) complexes with lecithin and cholesterol that coexist with lipid-stabilized (400-800 nm) DAG oil droplets. This microstructural transition from vesicles to complexes avoids nucleation of cholesterol crystals and is a newly discovered mechanism by which apo A-I serves as an antinucleating agent in bile. The critical value at which a microstructural transition occurs depends on binding of apo A-I and so varies with the cholesterol mole fraction of vesicles. Aggregation of small, unilamellar, egg lecithin vesicles (SUVs) with varying cholesterol composition (0-60 mol %) was monitored for a range of apo A-I concentrations (2 to 89 μg/mL). Suppression of aggregation persists so long as the DAG-to-bound-apo A-I molar ratio is less than 100. A fluorescence assay involving dansylated lecithin shows that the suppression is an indirect effect of apo A-I rather than a direct inhibition of PLC enzyme activity. The DAG-to-total apo A-I molar ratio at which suppression is lost increases with cholesterol because of differences in apo A-I binding. Above this value, a microstructural transition to DAG droplets and lecithin/cholesterol A-I complexes occurs, as evidenced by sudden increases in turbidity and size and enhancement of Förster resonance energy transfer; structures are confirmed by cryo TEM. © 2005 American Chemical Society.en_HK
dc.languageengen_HK
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/biochemistryen_HK
dc.relation.ispartofBiochemistryen_HK
dc.subjectChemicals And Cas Registry Numbersen_HK
dc.titleCombined interaction of phospholipase C and apolipoprotein A-I with small unilamellar lecithin-cholesterol vesicles: Influence of apolipoprotein A-I concentration and vesicle compositionen_HK
dc.typeArticleen_HK
dc.identifier.emailLee, SP: sumlee@hku.hken_HK
dc.identifier.authorityLee, SP=rp01351en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1021/bi047317men_HK
dc.identifier.pmid15882068-
dc.identifier.scopuseid_2-s2.0-18544363902en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-18544363902&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume44en_HK
dc.identifier.issue19en_HK
dc.identifier.spage7294en_HK
dc.identifier.epage7304en_HK
dc.identifier.isiWOS:000229057600021-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridGudheti, MV=16024338300en_HK
dc.identifier.scopusauthoridLee, SP=7601417497en_HK
dc.identifier.scopusauthoridDanino, D=7003981949en_HK
dc.identifier.scopusauthoridWrenn, SP=6603940041en_HK

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