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Cys10 mixed disulfides make transthyretin more amyloidogenic under mildly acidic conditions

Academic Article
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Overview

authors

  • Zhang, Qinghai
  • Kelly, Jeffery

publication date

  • 2003

journal

  • Biochemistry  Journal

abstract

  • Conservative mutation of transthyretin's surface residues can predispose an individual to familial amyloidosis by dramatically changing the energetics of misfolding. Senile systemic amyloidosis (SSA), however, cannot be explained in this fashion because wild-type (WT) transthyretin (TTR) misfolds and misassembles into amyloid. Since various modifications of the SH functionality of Cys10 have been reported in humans, we sought to understand the extent to which these modifications alter the stability and amyloidosis of WT TTR as a possible explanation for SSA. Homotetrameric Cys10 TTR variants, including TTR-Cys, TTR-GSH, TTR-CysGly, and S-sulfonated TTR, were chemically synthesized starting with WT TTR. The TTR-Cys, TTR-GSH, and TTR-CysGly isoforms are more amyloidogenic than WT at the higher end of the acidic pH range (pH 4.4-5.0), and they are similarly destabilized relative to WT TTR toward urea denaturation. They exhibit rates of urea-mediated tetramer dissociation (pH 7) and MeOH-facilitated fibril formation similar to those of WT TTR. Under mildly acidic conditions (pH 4.8), the amyloidogenesis rates of the mixed disulfide TTR variants are much faster than the WT rate. S-Sulfonated TTR is less amyloidogenic and forms fibrils more slowly than WT under acidic conditions, yet it exhibits a stability and rates of tetramer dissociation similar to those of WT TTR when subjected to urea denaturation. Conversion of the Cys10 SH group to a mixed disulfide with the amino acid Cys, the CysGly peptide, or glutathione increases amyloidogenicity and the amyloidogenesis rate above pH 4.6, conditions under which TTR probably forms fibrils in humans. Hence, these modifications may play an important role in human amyloidosis.

subject areas

  • Amyloid
  • Cysteine
  • Disulfides
  • Dose-Response Relationship, Drug
  • Escherichia coli
  • Humans
  • Hydrogen-Ion Concentration
  • Kinetics
  • Models, Chemical
  • Peptides
  • Prealbumin
  • Protein Folding
  • Protein Isoforms
  • Temperature
  • Time Factors
  • Urea
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Identity

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi030077a

PubMed ID

  • 12873136
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Additional Document Info

start page

  • 8756

end page

  • 8761

volume

  • 42

issue

  • 29

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