Increasing Prion Propensity by Hydrophobic Insertion
Figure 7
Amino acid composition of prion and non-prion Q/N-rich domains.
(A) Histogram of the prevalence of strongly prion-promoting residues (FYWIMV) among Q/N-rich proteins (open bars) and among peptide fragments from the yeast proteome (black bars). For the Q/N-rich proteins, each of the regions of the yeast proteome identified by Harrison and Gerstein [16] as having high Q/N-bias were scored for the fraction of strongly prion-promoting amino acids. For the proteomic data, the yeast proteome was scanned using a 100 amino acid window size; each 100-amino-acid window was scored for the fraction of strongly prion-promoting amino acids. (B) Histogram of the prevalence of strongly prion-promoting amino acids among yeast prion and non-prion Q/N-rich domains. The black bars include Q/N-rich regions (as identified by Harrison and Gerstein) from yeast proteins shown to act as prions, as well as from proteins containing domains shown by Alberti et al. to have prion-like activity in four independent assays [19]. Open bars represent all other yeast Q/N-rich regions identified by Harrison and Gerstein. (C) Amino acid prevalence in Q/N-rich domains. Grey bars represent the prevalence of different groups of amino acids in the yeast proteome. Black bars represent the average frequency of these amino acids among Q/N-rich regions from both proteins shown to act as prions and proteins containing domains shown by Alberti et al. to have prion-like activity in four independent assays. Open bars represent the average frequency of these amino acids among all other yeast Q/N-rich domains identified by Harrison and Gerstein. (D) The prevalence of different groups of amino acids, plotted as a fraction of non-Q/N residues.