The RNA-Binding Protein Scp160p Facilitates Aggregation of Many Endogenous Q/N-Rich Proteins

The RNA-binding protein Scp160p is the yeast homolog of the conserved vigilin protein family. These proteins influence a variety of nuclear and cytoplasmic functions. One of Scp160p's reported roles is to increase translation elongation efficiency in a manner related to codon usage. Thus, it can affect translation speed and co-translational folding of nascent peptides. We used polyglutamine (polyQ) reporters to assess Scp160p's effect on protein synthesis and observed that, in the absence of Scp160p, aggregation of polyQ is reduced and toxicity is abolished. We additionally took a proteomic approach and analyzed the impact of Scp160p on the aggregation of endogenous proteins under normal growth conditions. In the absence of Scp160p, aggregation of many Q/N-rich proteins was reduced. Because aggregation mediated by these regions can be important for the proteins' functions, Scp160p may affect many processes via aggregation of Q/N-rich proteins.