Interhelical contacts are required for the helix bundle fold of apolipophorin III and its ability to interact with lipoproteins

Protein Science : a Publication of the Protein Society
J WangR O Ryan

Abstract

Apolipophorin-III (apoLp-III) from the insect, Manduca sexta, is a 166-residue exchangeable apolipoprotein that plays a critical role in the dynamics of plasma lipoprotein interconversions. Our previous work indicated that a 36-residue C-terminal peptide fragment, generated by cyanogen bromide digestion of apoLp-III, was unable to bind to lipid surfaces (Narayanaswami V, Kay CM, Oikawa K, Ryan RO, 1994, Biochemistry 33:13312-13320), and showed no secondary structure in aqueous solution. In this paper, we have performed structural studies of this peptide (E131-Q166) complexed with SDS detergent micelles, or in the presence of the helix-inducing solvent trifluoroethanol (TFE), by two-dimensional 1H NMR spectroscopy. The peptide adopts an alpha-helical structure in the presence of both SDS and 50% TFE. The lipid-bound structure of the peptide, generated from the NMR NOE data, showed an elongated, slightly curved alpha-helix. Despite its high alpha-helix forming propensity, the peptide requires alpha helix-promoting environment to adopt an alpha-helical structure. This indicates the importance of the surrounding chemical environment and implies that, in the absence of lipid, tertiary contacts in the folded protein play a role in ma...Continue Reading

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Citations

Dec 22, 1999·Biochimica Et Biophysica Acta·V Narayanaswami, R O Ryan
Oct 31, 2009·International Journal of Biological Macromolecules·Peng QuZuhong Lu
Jul 19, 2011·Future Virology·Miles C SmithDavid J Davido

Related Concepts

Apolipophorin-II
Apolipoproteins
Lipoproteins
In Vivo NMR Spectroscopy
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