Apolipoprotein A-I configuration and cell cholesterol efflux activity of discoidal 6 lipoproteins depend on the reconstitution process

CUELLAR, LUZ ANGELA; PRIETO EDUARDO DANIEL; GARDA HORACIO; CABALEIRO, LAURA VIRGINIA

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR AND CELL BIOLOGY OF LIPIDS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013

1388-1981

Discoidal high-density lipoproteins (D-HDL) are critical intermediates in reverse cholesterol transport. Most of 23the present knowledge of D-HDL is based on studies with reconstituted lipoprotein complexes of apolipoprotein 24A-I (apoA-I) obtained by cholate dialysis (CD). D-HDL can also be generated by the direct microsolubilization 25(DM) of phospholipid vesicles at the gel/fluid phase transition temperature, a process mechanistically similar 26to the ?in vivo? apoAI lipidation via ABCA1. We compared the apoA-I configuration in D-HDL reconstituted 27with dimyristoylphosphatidylcholine by both procedures using fluorescence resonance energy transfermeasure- 28ments with apoA-I tryptophan mutants and fluorescently labeled cysteine mutants. Results indicate that apoA-I 29configuration in D-HDL depends on the reconstitution process and are consistentwith a ?double belt? molecular arrangementwith different helix registry. As reported by others, a configurationwith juxtaposition of helices 5 of each apoAImonomer (5/5 registry) predominates in D-HDL obtained by CD. However, a configurationwith helix 5 of onemonomer juxtaposedwith helix 2 of the other (5/2 registry)would predominate in D-HDL generated by DM.Moreover,we also showthat the kinetics of cholesterol efflux frommacrophage cultures depends on the reconstitution process, suggesting that apoAI configuration is important for this HDL function.