Structural Features of Heparin and Its Interactions With Cellular Prion Protein Measured by Surface Plasmon Resonance.

Fuming Zhang,David A Harris,So Young Kim,Robert J Linhardt

doi:10.3389/fmolb.2020.594497

Abstract

Self-propagating form of the prion protein (PrPSc) causes many neurodegenerative diseases, such as Creutzfeldt-Jakob disease (CJD) and Gerstmann-Straussler-Scheinker syndrome (GSS). Heparin is a highly sulfated linear glycosaminoglycan (GAG) and is composed of alternating D-glucosamine and L-iduronic acid or D-glucuronic acid sugar residues. The interactions of heparin with various proteins in a domain-specific or charged-dependent manner provide key roles on many physiological and pathological processes. While GAG-PrP interactions had been previously reported, the specific glycan structures that facilitate interactions with different regions of PrP and their binding kinetics have not been systematically investigated. In this study, we performed direct binding surface plasmon resonance (SPR) assay to characterize the kinetics of heparin binding to four recombinant murine PrP constructs including full length (M23–230), a deletion mutant lacking the four histidine-containing octapeptide repeats (M23–230 Δ59–90), the isolated N-terminal domain (M23–109), and the isolated C-terminal domain (M90–230). Additionally, we found the specific structural determinants required for GAG binding to the four PrP constructs with chemically defined derivatives of heparin and other GAGs by an SPR competition assay. Our findings may be instrumental in developing designer GAGs for specific targets within the PrP to fine-tune biological and pathophysiological activities of PrP.

Highlights

A group of neurodegenerative diseases, including Creutzfeldt-Jakob disease (CJD) and GerstmannStraussler-Scheinker syndrome (GSS), are caused by an infectious, self-propagating form of the prion protein, PrPSc (Mercer et al, 2018)
low molecular weight heparin (LMWH) and unfractionated heparin inhibited PrP-heparin interactions more effectively, by 60 and 80%, respectively (Figure 4A). These results demonstrate that full length PrP prefers bindings to longer heparin chains
Our investigation shows that full length PrP (M23–230) binds heparin with greatest binding affinity (KD = 0.11 μM) followed by the N-terminus region PrP (M23–109) (KD = 0.71 μM), and mutant PrP (M23–230 59–90) (KD = 3.3 μM) (Figure 3 and Table 1)

Summary

Introduction

A group of neurodegenerative diseases, including Creutzfeldt-Jakob disease (CJD) and GerstmannStraussler-Scheinker syndrome (GSS), are caused by an infectious, self-propagating form of the prion protein, PrPSc (Mercer et al, 2018). Heparin Interactions With Cellular Prion Protein change in PrPC, which leads, through an autocatalytic process, to accumulation of protease-resistant PrPSc in the brain. As part of this process, PrPSc activates a PrPC-dependent signal transduction pathway that results in neurotoxicity (Le et al, 2019). This toxic pathway depends critically on the N-terminal domain of PrPC (Solomon et al, 2011; Westergard et al, 2011; Wu et al, 2017). The PrPC molecule is comprised of two major structural domains: a flexible, natively unstructured N-terminal domain (residues 23–127), and a structured, globular C-terminal domain (residues 128–230) (Zahn et al, 2000)

Methods

Results

Conclusion