Structural analysis of peptide-analogues of human Zona Pellucida ZP1 protein with amyloidogenic properties: insights into mammalian Zona Pellucida formation

PLoS One. 2013 Sep 12;8(9):e73258. doi: 10.1371/journal.pone.0073258. eCollection 2013.

Abstract

Zona pellucida (ZP) is an extracellular matrix surrounding and protecting mammalian and fish oocytes, which is responsible for sperm binding. Mammalian ZP consists of three to four glycoproteins, called ZP1, ZP2, ZP3, ZP4. These proteins polymerize into long interconnected filaments, through a common structural unit, known as the ZP domain, which consists of two domains, ZP-N and ZP-C. ZP is related in function to silkmoth chorion and in an evolutionary fashion to the teleostean fish chorion, also fibrous structures protecting the oocyte and embryo, that both have been proven to be functional amyloids. Two peptides were predicted as 'aggregation-prone' by our prediction tool, AMYLPRED, from the sequence of the human ZP1-N domain. Here, we present results from transmission electron microscopy, X-ray diffraction, Congo red staining and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR FT-IR), of two synthetic peptide-analogues of these predicted 'aggregation-prone' parts of the human ZP1-N domain, that we consider crucial for ZP protein polymerization, showing that they both self-assemble into amyloid-like fibrils. Based on our experimental data, we propose that human ZP (hZP) might be considered as a novel, putative, natural protective amyloid, in close analogy to silkmoth and teleostean fish chorions. Experiments are in progress to verify this proposal. We also attempt to provide insights into ZP formation, proposing a possible model for hZP1-N domain polymerization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Egg Proteins / chemistry*
  • Humans
  • Membrane Glycoproteins / chemistry*
  • Peptides / chemistry*
  • Peptides / metabolism
  • Receptors, Cell Surface / chemistry*
  • Spectroscopy, Fourier Transform Infrared
  • X-Ray Diffraction
  • Zona Pellucida / metabolism*
  • Zona Pellucida Glycoproteins

Substances

  • Egg Proteins
  • Membrane Glycoproteins
  • Peptides
  • Receptors, Cell Surface
  • ZP1 protein, human
  • ZP2 protein, human
  • ZP3 protein, human
  • Zona Pellucida Glycoproteins

Grant support

The authors thank the University of Athens for support. This work was funded by the SYNERGASIA 2011 PROGRAMME, co-funded by the European Regional Development Fund and National resources (Project Code 11SYN_1_1230). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.