title: A short Id2 protein fragment containing the nuclear export signal forms amyloid-like fibrils.
abstract: The negative regulator of DNA-binding/cell-differentiation Id2 is a small protein containing a central helix-loop-helix (HLH) motif and a C-terminal nuclear export signal (NES). Whereas the former is essential for Id2 dimerization and nuclear localization, the latter is responsible for the transport of Id2 from the nucleus to the cytoplasm. Whereas the isolated Id2 HLH motif is highly helical, large C-terminal Id2 fragments including the NES sequence are either unordered or aggregation-prone. To study the conformational properties of the isolated NES region, we synthesized the Id2 segment 103-124. The latter was insoluble in water and only temporarily soluble in water/alcohol mixtures, where it formed quickly precipitating beta-sheets. Introduction of a positively charged N-terminal tail prevented aggressive precipitation and led to aggregates consisting of long fibrils that bound thioflavin T. These results show an interesting structural aspect of the Id2 NES region, which might be of significance for both protein folding and function.
authors.affiliation: Fakultät für Chemie und Pharmazie, Universität Regensburg, 93053 Regensburg, Germany.
authors.forename: Noemi
authors.initials: N
authors.lastname: Colombo
authors.forename: Josef
authors.initials: J
authors.lastname: Schroeder
authors.forename: Chiara
authors.initials: C
authors.lastname: Cabrele
mesh_terms: D000682:Amyloid / Q000096:biosynthesis; D000818:Animals; D002942:Circular Dichroism; D051797:Inhibitor of Differentiation Protein 2 / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D008854:Microscopy, Electron; D049790:Nuclear Export Signals / Q000502:physiology*; D010446:Peptide Fragments / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary
chemical_list: D000682:Amyloid; D051797:Inhibitor of Differentiation Protein 2; D049790:Nuclear Export Signals; D010446:Peptide Fragments