Zinc-binding structure of a catalytic amyloid from solid-state NMR

Myungwoon Lee, Tuo Wang, Olga V. Makhlynets, Yibing Wu, Nicholas F. Polizzi, Haifan Wu, Pallavi M. Gosavi, Jan Stöhr, Ivan V. Korendovych, William F. Degrado, Mei Hong

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Throughout biology, amyloids are key structures in both functional proteins and the end product of pathologic protein misfolding. Amyloids might also represent an early precursor in the evolution of life because of their small molecular size and their ability to selfpurify and catalyze chemical reactions. They also provide attractive backbones for advanced materials. When β-strands of an amyloid are arranged parallel and in register, side chains from the same position of each chain align, facilitating metal chelation when the residues are good ligands such as histidine. High-resolution structures of metalloamyloids are needed to understand the molecular bases of metal-amyloid interactions. Here we combine solid-state NMR and structural bioinformatics to determine the structure of a zinc-bound metalloamyloid that catalyzes ester hydrolysis. The peptide forms amphiphilic parallel β-sheets that assemble into stacked bilayers with alternating hydrophobic and polar interfaces. The hydrophobic interface is stabilized by apolar side chains from adjacent sheets, whereas the hydrated polar interface houses the Zn2+-binding histidines with binding geometries unusual in proteins. Each Zn2+ has two bis-coordinated histidine ligands, which bridge adjacent strands to form an infinite metal-ligand chain along the fibril axis. A third histidine completes the protein ligand environment, leaving a free site on the Zn2+ for water activation. This structure defines a class of materials, which we call metal-peptide frameworks. The structure reveals a delicate interplay through which metal ions stabilize the amyloid structure, which in turn shapes the ligand geometry and catalytic reactivity of Zn2+.

Original languageEnglish (US)
Pages (from-to)6191-6196
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number24
DOIs
StatePublished - Jun 13 2017

Keywords

  • Histidine
  • Magic angle spinning
  • Metal-peptide framework
  • Metalloprotein

ASJC Scopus subject areas

  • General

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