Opposing effects of glutamine and asparagine govern prion formation by intrinsically disordered proteins

Halfmann R, Alberti S, Krishnan R, Lyle N, O’Donnell CW, King OD, Berger B, Pappu RV, Lindquist S (2011). Mol Cell, 43(1):72-84
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Abstract

Sequences rich in glutamine (Q) and asparagine (N) residues often fail to fold at the monomer level. This, coupled to their unusual hydrogen-bonding abilities, provides the driving force to switch between disordered monomers and amyloids. Such transitions govern processes as diverse as human protein-folding diseases, bacterial biofilm assembly, and the inheritance of yeast prions (protein-based genetic elements). A systematic survey of prion-forming domains suggested that Q and N residues have distinct effects on amyloid formation. Here, we use cell biological, biochemical, and computational techniques to compare Q/N-rich protein variants, replacing Ns with Qs and Qs with Ns. We find that the two residues have strong and opposing effects: N richness promotes assembly of benign self-templating amyloids; Q richness promotes formation of toxic nonamyloid conformers. Molecular simulations focusing on intrinsic folding differences between Qs and Ns suggest that their different behaviors are due to the enhanced turn-forming propensity of Ns over Qs.

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Posted on October 24, 2011
Posted in: HPAN, Neurodegeneration, Publications Authors: