Prion Protein of 106 Residues Creates an Artificial Transmission Barrier for Prion Replication in Transgenic Mice

Abstract

A redacted prion protein (PrP) of 106 amino acids with two large deletions was expressed in transgenic (Tg) mice deficient for wild-type (wt) PrP (Prnp0/0) and supported prion propagation. RML prions containing full-length PrP(Sc)produced disease in Tg(PrP106)Prnp0/0 mice after approximately 300 days, while transmission of RML106 prions containing PrP(Sc)106 created disease in Tg(PrP106) Prnp0/0 mice after only approximately 66 days on repeated passage. This artificial transmission barrier for the passage of RML prions was diminished by the coexpression of wt MoPrPc in Tg(PrP106)Prnp+/0 mice that developed scrapie in approximately 165 days, suggesting that wt MoPrP acts in trans to accelerate replication of RML106 prions. Purified PrP(Sc)106 was protease resistant, formed filaments, and was insoluble in nondenaturing detergents. The unique features of RML106 prions offer insights into the mechanism of prion replication, and the small size of PrP(Sc)106 should facilitate structural analysis.

Molecular Dynamics as an Approach to Study Prion Protein Misfolding and the Effect of Pathogenic Mutations

“…Further strands sometimes form in the remaining part that was included in the simulation. Antibody studies indicate that residues 90-120 undergo a conformational change upon conversion to PrP Sc [112][113][114] and a range of studies support the involvement of residues in this region in PrP Sc formation [108,110,111,115]. Our misfolding simulations also indicate the formation of an isolated strand in the loop preceding HA (res.…”

“…The limitation of this work and other studies [62,106], however, is that the flexible N-terminus was not included in the simulations. There are many indications from experiment that at least part of this region plays a role in misfolding and aggregation [108][109][110][111]. We have therefore always included part of the flexible N-terminus in our simulations.…”

Truncated forms of the prion protein PrP demonstrate the need for complexity in prion structure

“…24,25 Nevertheless, it is too small to form the full 4-rung b-solenoid, and in this sense, can only be a partial model for PrP Sc . PrP Sc 106 forms a 4-rung b-solenoid, and is also infectious, 14 and of the fragments examined, it may be the best model for PrP Sc . However, both PrP55 and PrP Sc 106 exhibit high levels of disorder, and PrP55 does not consistently form b-solenoidal structures, so these fragment models offer limited advantages if any over PrP Sc and PrP 27-30 as objects of structural studies.…”

Dissociation of recombinant prion autocatalysis from infectivity

“…14 Furthermore, the complete absence of the a 1 -b 2 domain in a redacted 'miniprion' does not prevent PrP Sc formation, but such miniprions are non-infectious when inoculated into animals expressing full-length PrP. 15 Finally, the a 1 -b 2 domain also lies immediately adjacent to the b 2 -a 2 loop, a region with notable influence on prion formation and interspecies prion transmission. 16 …”