Apolipoprotein A-I configuration and cell cholesterol efflux activity of discoidal lipoproteins depend on the reconstitution process

CUELLAR, LUZ ANGELA; PRIETO E.D; CAVALEIRO, LAURA; GARDA HORACIO

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR AND CELL BIOLOGY OF LIPIDS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013 vol. 1841 p. 180 - 189

1388-1981

Discoidal high-density lipoproteins (D-HDL) are critical intermediates in reverse cholesterol transport. Most ofthe present knowledge of D-HDL is based on studies with reconstituted lipoprotein complexes of apolipoproteinA-I (apoA-I) obtained by cholate dialysis (CD). D-HDL can also be generated by the direct microsolubilization(DM) of phospholipid vesicles at the gel/fluid phase transition temperature, a process mechanistically similarto the ?in vivo? apoAI lipidation via ABCA1. We compared the apoA-I configuration in D-HDL reconstitutedwith dimyristoylphosphatidylcholine by both procedures using fluorescence resonance energy transfermeasurementswith apoA-I tryptophan mutants and fluorescently labeled cysteine mutants. Results indicate that apoA-Iconfiguration in D-HDL depends on the reconstitution process and are consistentwith a ?double belt? molecular arrangementwith different helix registry. As reported by others, a configuration with juxtaposition of helices 5 of each apoAImonomer (5/5 registry) predominates in D-HDL obtained by CD. However, a configurationwith helix 5 of one monomer juxtaposedwith helix 2 of the other (5/2 registry) would predominate in D-HDL generated by DM.Moreover, we also show that the kinetics of cholesterol efflux from macrophage cultures depends on the reconstitution process, suggesting that apoAI configuration is important for this HDL function