Quantifying size distributions of nanolipoprotein particles with single-particle analysis and molecular dynamic simulations

Craig D. Blanchette, Richard Law, W. Henry Benner, Joseph B. Pesavento, Jenny A. Cappuccio, Vicki Walsworth, Edward A. Kuhn, Michele Corzett, Brett A. Chromy, Brent W. Segelke, Matthew A. Coleman, Graham Bench (+2 others)
2008 Journal of Lipid Research  
Self-assembly of purified apolipoproteins and phospholipids results in the formation of nanometer-sized lipoprotein complexes, referred to as nanolipoprotein particles (NLPs). These bilayer constructs are fully soluble in aqueous environments and hold great promise as a model system to aid in solubilizing membrane proteins. Size variability in the self-assembly process has been recognized for some time, yet limited studies have been conducted to examine this phenomenon. Understanding the source
more » ... of this heterogeneity may lead to methods to mitigate heterogeneity or to control NLP size, which may be important for tailoring NLPs for specific membrane proteins. Here, we have used atomic force microscopy, ion mobility spectrometry, and transmission electron microscopy to quantify NLP size distributions on the single-particle scale, specifically focusing on assemblies with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and a recombinant apolipoprotein E variant containing the N-terminal 22 kDa fragment (E422k). Four discrete sizes of E422k/DMPC NLPs were identified by all three techniques, with diameters centered at ?14.5, 19, 23.5, and 28 nm. Computer simulations suggest that these sizes are related to the structure and number of E422k lipoproteins surrounding the NLPs and particles with an odd number of lipoproteins are consistent with the double-belt model, in which at least one lipoprotein adopts a hairpin structureQuantifying size distributions of nanolipoprotein particles with single-particle analysis and molecular dynamic simulations. J. Lipid Res. 2008Res. . 49: 1420Res. -1430 Supplementary key words apolipoproteins • nanodiscs • high density lipoproteins • atomic force microscopy • ion mobility spectrometry
doi:10.1194/jlr.m700586-jlr200 pmid:18403317 fatcat:ymejujz3tvgizaafzxyz272uie