Quiescin-sulfhydryl oxidase inhibits prion formation in vitro

Abstract

Prions are infectious proteins that cause a group of fatal transmissible diseases in animals and humans. The scrapie isoform (PrPSc) of the cellular prion protein (PrPC) is the only known component of the prion. Several lines of evidence have suggested that the formation and molecular features of PrPSc are associated with an abnormal unfolding/refolding process. Quiescin-sulfhydryl oxidase (QSOX) plays a role in protein folding by introducing disulfides into unfolded reduced proteins. Here we report that QSOX inhibits human prion propagation in protein misfolding cyclic amplification reactions and murine prion propagation in scrapie-infected neuroblastoma cells. Moreover, QSOX preferentially binds PrPSc from prion-infected human or animal brains, but not PrPC from uninfected brains. Surface plasmon resonance of the recombinant mouse PrP (moPrP) demonstrates that the affinity of QSOX for monomer is significantly lower than that for octamer (312 nM vs 1.7 nM). QSOX exhibits much lower affinity for N-terminally truncated moPrP (PrP89-230) than for the full-length moPrP (PrP23-231) (312 nM vs 2 nM), suggesting that the N-terminal region of PrP is critical for the interaction of PrP with QSOX. Our study indicates that QSOX may play a role in prion formation, which may open new therapeutic avenues for treating prion diseases.

Soluble polymorphic bank vole prion proteins induced by co-expression of quiescin sulfhydryl oxidase in E. coli and their aggregation behaviors

“…Our recent study demonstrated that QSOX is able to bind different species of PrP Sc and inhibit PrP Sc formation in vitro [ 14 ]. Surface Plasmon Resonance (SPR) was used to determine the dissociation constant ( Kd ) of this interaction.…”

“…The interaction between QSOX and the full-length rBVPrP-109M or rBVPrP-109I was studied using surface plasmon resonance (SPR) with a BIAcore 3000 instrument as described previously [ 14 ]. QSOX was diluted to 2 µg/mL in 10 mM sodium acetate, pH 5.2, and covalently linked to a Sensor Chip CM5 (carboxymethylated dextran surface) using the amine coupling chemistry.…”

“…In this work, we described the production of soluble human and mouse prion proteins for the first time in the E. coli cytoplasm by the co-expression with QSOX [ 13 ]. Recently, we further observed that QSOX can highly and efficiently interact with PrP Sc , but not PrP C , isolated from the human brain by inhibiting PrP Sc formation in vitro [ 14 ]. In the current study, we report that QSOX can be used to produce a large amount of soluble recombinant bank vole PrP (rBVPrP) with two different polymorphisms either rBVPrP-109I or rBVPrP-109M in E. coli .…”

Urine proteomics for profiling of mouse toxoplasmosis using liquid chromatography tandem mass spectrometry analysis

“…Sulfhydryl oxidase 1, complement C3, cystatin-3 and alpha-1-acid glycoprotein 2 were the four most highly connected DEPs in the network. Sulfhydryl oxidase 1, a catalyst of disulfide bond formation, catalyzes the oxidation of sulfhydryl groups in peptide and introduces disulfides into unfolded reduced proteins, which play crucial roles in many diseases, such as cancer and prion formation [ 25 , 26 ]. Cystatin-3 (also named cystatin-C), a cysteine protease inhibitor, functions as an inflammatory factor and has been widely recognized as a novel biomarker to predict the kidney function [ 27 ].…”