Chapter 5: Prions Flashcards
Non-Mendelian trait
A trait that is inherited with a 100% chance compared to 25% for Mendelian genetics
What domain is essential for Sup35 prion activity?
N domain rich in Glutamine/Asparagine, upon removal no prion activity is observed
What domain is non-essential for Sup35 prion activity?
C domain, prions are observed when only N & M are present; in fact other proteins can be transformed into prions by insertion of those domains
In Sup35, what are main features/functions of M domain
> Rich in charges
Keeps protein soluble
Switch between the normal and prion states
What regulates [PSI+] activity
Hsp104 -> tight regulation of aggregation
Fusion protein construct
Protein fused with GFP
Five common features of all prions
1) Form amyloid fibers
2) Aggregates are protease resistant
3) Seeded aggregation
4) Bind Congo Red
5) Have strains
Explain the strain difference
Smaller core is more fragile, weaker bonds in the aggregate form lead to breakage, which gives new seeds and convert more protein into aggregate form. Main point: structural difference
What are some advantages of prions
[PSI+] reveals cryptic genetic variation
Epigenetic, same DNA can yield different phenotypes
Provide evolutionary advantage under changing environmental conditions
Are all amyloids toxic?
No, in fact some hormones are stored as amyloid fibers due to compact and economic packing
Define proteostasis
Protein homeostasis
What contributes to the species barrier
1) Difference in the PrP sequence between donor and recipient
2) Prion strain
What would ultimately prove prion hypothesis
If both prion from infected tissue and synthesized prion will exhibit the same effect on the organism
How protein nature of the prion was determined?
Resistant to UV radiation and nuclease digestion, hence cannot be virus or bacteria
Are all amyloids toxic?
No, in fact some hormones are stored as amyloid fibers due to compact and economic packing
