Partitioning of membrane-anchored DNA between coexisting lipid phases.
The partitioning of different cholesterol-modified single-stranded DNA molecules (chol-DNAs) between the domains of phase-separated lipid vesicles is investigated by laser-scanning confocal fluorescence microscopy. All chol-DNAs studied preferentially localized into the fluid phase of giant vesicles in liquid-solid phase coexistence (1:1 DLPC:DPPC, 1:1 DLPC:DMPE). Partitioning behavior of chol-DNAs into liquid-liquid phase-separated vesicles (DOPC/DPPC/cholesterol) was found to be less straightforward. Single-cholesterol-anchored DNA molecules partitioned roughly equally between coexisting domains, whereas chol-DNAs with two cholesterol anchors were seen to be enriched in the liquid-ordered domains with apparent surface concentrations up to double that of the liquid-disordered phase. Quantitative analysis of the fluorescence intensity of DNA between the two phases also revealed a weaker dependence of the apparent partitioning on the initial lipid composition of the vesicles. We rationalize these observations by proposing a simple partitioning model based on the conformational entropy of insertion of a cholesterol anchor into each phase.
Beales
Paul A
PA
Department of Chemical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Vanderlick
T Kyle
TK
D002784:Cholesterol / Q000737:chemistry; D004277:DNA, Single-Stranded / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D008856:Microscopy, Fluorescence; D008968:Molecular Conformation; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D053835:Unilamellar Liposomes / Q000737:chemistry*
D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D053835:Unilamellar Liposomes; C015153:1,2-dilauroylphosphatidylcholine; D002784:Cholesterol; C017251:1,2-oleoylphosphatidylcholine; C018525:1,2-dimyristoylphosphatidylethanolamine