Faculty Collaboration Database

Single repeat deletion in ApoA-I blocks cholesterol esterification and results in rapid catabolism of delta6 and wild-type ApoA-I in transgenic mice. J Biol Chem 2000 Apr 21;275(16):12156-63

Date

04/15/2000

Pubmed ID

10766851

DOI

10.1074/jbc.275.16.12156

Scopus ID

2-s2.0-0034697316 (requires institutional sign-in at Scopus site)   43 Citations

Abstract

The deletion mutation Delta6 apolipoprotein A-I lacks residues 143-164 or repeat 6 in the mature apoA-I protein. In vitro studies show this mutation dramatically reduces the rate of lecithin:cholesterol acyltransferase (LCAT) catalyzed cholesterol esterification. The present study was initiated to investigate the effect of this mutation on in vivo high density lipoprotein (HDL) cholesterol esterification and metabolism. Transgenic mice expressing human Delta6 apoA-I (TgDelta6 +/+) were created and then crossed with apoA-I knockout mice (-/-) to generate mice expressing only human Delta6 apoA-I (TgDelta6 -/-). Human Delta6 apoA-I was associated with homogeneous sized alpha-HDL, when wild-type mouse apoA-I was present (in TgDelta6 +/+ and +/- mice). However, in the absence of endogenous mouse apoA-I, Delta6 apoA-I was found exclusively in cholesterol ester-poor HDL, and lipid-free HDL fractions. This observation coincides with the 6-fold lower cholesterol ester mass in TgDelta6 -/- mouse plasma compared with control. Structural studies show that despite the structural perturbation of a domain extending from repeat 5 to repeat 8 (137-178), Delta6 apoA-I binds to spherical unilamellar vesicles with only 2-fold less binding affinity. In summary, these data show a domain corresponding to apoA-I repeat 6 is responsible for providing an essential conformation for LCAT catalyzed generation of cholesterol esters. Deletion of apoA-I repeat 6 not only blocks normal levels of cholesterol esterification but also exerts a dominant inhibition on the ability of wild-type apoA-I to activate LCAT in vivo.

Author List

Sorci-Thomas MG, Thomas M, Curtiss L, Landrum M

Author

Mary Sorci Thomas PhD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Apolipoprotein A-I
Apolipoproteins A
Blotting, Western
Cholesterol Esters
Cholesterol, HDL
Chromatography, High Pressure Liquid
Electrophoresis, Polyacrylamide Gel
Humans
Lipid Bilayers
Mice
Mice, Knockout
Mice, Transgenic
Protein Denaturation
Sequence Deletion
Structure-Activity Relationship