Mapping the structural transition in an amyloidogenic apolipoprotein A-I

Jens O. Lagerstedt, Giorgio Cavigiolio, Linda M. Roberts, Hyun Seok Hong, Lee-Way Jin, Paul G FitzGerald, Michael N. Oda, John C Voss

Research output: Contribution to journalArticle

40 Scopus citations

Abstract

The single amino acid mutation G26R in human apolipoprotein A-I (apoA-IIOWA) leads to the formation of β-secondary structure rich amyloid fibrils in vivo. Here we show that full-length apoA-I IOWA has a decreased lipid-binding capability, an increased amino-terminal sensitivity to protease, and a propensity to form annular protofibrils visible by electron microscopy. The molecular basis for the conversion of apolipoprotein A-I to a proamyloidogenic form was examined by electron paramagnetic resonance spectroscopy. Our recent findings [Lagerstedt, J. O., Budamagunta, M. S., Oda, M. N., and Voss, J. C. (2007) J. Biol. Chem. 282, 9143-9149] indicate that Gly26 in the native apoprotein separates a preceding β-strand structure (residues 20-25) from a downstream largely α-helical region. The current study demonstrates that the G26R variant promotes a structural transition of positions 27-56 to a mixture of coil and β-strand secondary structure. Microscopy and staining by amyloidophilic dyes suggest that this alteration extends throughout the protein within 1 week of incubation in vitro, leading to insoluble aggregates of distinct morphology. The severe consequences of the Iowa mutation likely arise from the combination of losing the contribution of the native Gly residue in terminating β-strand propagation and the promotion of β-structure when an Arg is introduced adjacent to the succeeding residue of identical charge and size, Arg27.

Original languageEnglish (US)
Pages (from-to)9693-9699
Number of pages7
JournalBiochemistry
Volume46
Issue number34
DOIs
StatePublished - Aug 28 2007

ASJC Scopus subject areas

  • Biochemistry

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