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Amino acid substitutions [K16A] and [K28A] distinctly affect amyloid β-protein oligomerization
Journal article   Open access   Peer reviewed

Amino acid substitutions [K16A] and [K28A] distinctly affect amyloid β-protein oligomerization

Matjaž žganec, Nicholas Kruczek and Brigita Urbanc
Journal of biological physics, v 42(3), pp 453-476
Jun 2016
PMID: 27155979
url
https://doi.org/10.1007/s10867-016-9417-4View
Published, Version of Record (VoR) Open

Abstract

Structure-toxicity relationship Oligomerization Alzheimer’s disease Protein folding and assembly Original Paper Amyloid β-protein Oligomer structure
Amyloid β -protein (A β ) assembles into oligomers that play a seminal role in Alzheimer’s disease (AD), a leading cause of dementia among the elderly. Despite undisputed importance of A β oligomers, their structure and the basis of their toxicity remain elusive. Previous experimental studies revealed that the [K16A] substitution strongly inhibits toxicity of the two predominant A β alloforms in the brain, A β 40 and A β 42 , whereas the [K28A] substitution exerts only a moderate effect. Here, folding and oligomerization of [A16]A β 40 , [A28]A β 40 , [A16]A β 42 , and [A28]A β 42 are examined by discrete molecular dynamics (DMD) combined with a four-bead implicit solvent force field, DMD4B-HYDRA, and compared to A β 40 and A β 42 oligomer formation. Our results show that both substitutions promote A β 40 and A β 42 oligomerization and that structural changes to oligomers are substitution- and alloform-specific. The [K28A] substitution increases solvent-accessible surface area of hydrophobic residues and the intrapeptide N-to-C terminal distance within oligomers more than the [K16A] substitution. The [K16A] substitution decreases the overall β -strand content, whereas the [K28A] substitution exerts only a modest change. Substitution-specific tertiary and quaternary structure changes indicate that the [K16A] substitution induces formation of more compact oligomers than the [K28A] substitution. If the structure-function paradigm applies to A β oligomers, then the observed substitution-specific structural changes in A β 40 and A β 42 oligomers are critical for understanding the structural basis of A β oligomer toxicity and correct identification of therapeutic targets against AD.

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Web of Science research areas
Biophysics
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