<p> Apolipoprotein (apo) E3 (299 residues, ∼34 kDa) and apoAI (243 residues, ∼28 kDa) are exchangeable apolipoproteins that play a dominant role in regulating plasma cholesterol levels and are considered anti-atherogenic. The N-terminal (NT) domain of apoE3 mediates cellular uptake and clearance of plasma lipoproteins through the low density lipoprotein lipoprotein receptor (LDLr) family. The C-terminal (CT) domain of apoE3 lowers cholesterol levels through its ability to promote cholesterol efflux via ABCA1 (ATP binding cassette transporter AI), thereby mediating reverse cholesterol transport from peripheral tissues such as macrophages back to the liver. ApoAI is able to interact with phospholipid vesicles with high affinity and exhibits anti-atherogenic properties through its participation in the reverse cholesterol transport (RCT) pathway with high-density lipoprotein (HDL) and lecithin cholesterol acyltransferase (LCAT). The objective of this study was to determine the conformation and function of domain swapped chimeras of apoE3 and apoAI. Two domain swapped chimeras were generated: apoE3/apoAI and apoAI/apoE. The α-helical content of the chimeras were comparable to that of the parent proteins. Chemical denaturation studies of the chimeras revealed an unfolding profile that primarily follows the NT-domain of parents. While the apoAI/apoE chimera possessed lipid binding ability similar to its apoAI parent, the apoE3/apoAI chimera showed significant increase in lipid binding ability compared to apoE3. Whereas apoE3/apoAI elicits the ability to bind to the LDLr, apoAI/apoE did not. Lastly, both chimeras promoted ABCA1 mediated cholesterol efflux from J774 macrophages. These results show that CT of apoAI can promote lipid binding of apoE3, while CT of apoE3 can improve cholesterol efflux ability of apoAI. These findings contribute significantly to the development of therapeutic chimeras focused on reducing blood cholesterol levels.</p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:10196288 |
| Date | 04 January 2017 |
| Creators | Lek, Mark T. |
| Publisher | California State University, Long Beach |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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