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Despite its role in assembly, methionine 35 is not necessary for amyloid beta-protein toxicity

Panchanan Maiti1, Aleksey Lomakin, George B Benedek

  • 1Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA.

Journal of Neurochemistry
|March 30, 2010
PubMed

Insights

Oxidative stress is key in Alzheimer's disease pathology. This study found that modifying methionine 35 in amyloid beta-protein (A beta) did not significantly alter its neurotoxicity, challenging existing theories.

Area of Science:

  • Neuroscience
  • Biochemistry
  • Molecular Biology

Background:

  • Oxidative stress is a critical factor in Alzheimer's disease (AD) pathogenesis.
  • Methionine 35 (Met(35)) in amyloid beta-protein (A beta) is implicated in redox reactions that promote oxidative stress and A beta-induced toxicity.

Purpose of the Study:

  • To investigate the role of Met(35) in A beta toxicity by substituting it with non-redox-active residues.
  • To challenge the prevailing paradigm that Met(35) redox activity is essential for A beta neurotoxicity.

Main Methods:

  • Comparison of wild-type A beta 40 and A beta 42 with analogs containing Met(35) substitutions (Met(35)-->norleucine [Nle] or Met(35)-->Valine [Val]).
  • Utilized multiple biophysical and neurotoxicity assays to evaluate A beta assembly and toxicity.
  • Assessed the impact of substitutions on A beta self-assembly properties.

Main Results:

  • Substitutions of Met(35) with Nle or Val resulted in moderate alterations to A beta assembly.
  • Contrary to expectations, neither the Nle nor Val substitution significantly affected A beta neurotoxicity across three distinct assays.
  • The findings indicate that Met(35) may not be crucial for A beta's toxic mechanisms.

Conclusions:

  • The presence of Met(35) in A beta is not essential for its neurotoxicity.
  • This challenges the long-held view that redox reactions involving Met(35) significantly contribute to A beta-induced toxicity in Alzheimer's disease.

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