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Molecular insights into the role of the polyalanine region in mediating PHOX 2B aggregation
Author(s) -
Pirone Luciano,
Caldinelli Laura,
Di Lascio Simona,
Di Girolamo Rocco,
Di Gaetano Sonia,
Fornasari Diego,
Pollegioni Loredano,
Benfante Roberta,
Pedone Emilia
Publication year - 2019
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.14841
Subject(s) - gene , circular dichroism , fibril , chemistry , biology , biophysics , microbiology and biotechnology , biochemistry , genetics
About 90% of congenital central hypoventilation syndrome ( CCHS ) patients show polyalanine triplet expansions in the coding region of transcription factor PHOX 2B, which renders this protein an intriguing target to understand the insurgence of this syndrome and for the design of a novel therapeutical approach. Consistently with the role of PHOX 2B as a transcriptional regulator, it is reasonable that a general transcriptional dysregulation caused by the polyalanine expansion might represent an important mechanism underlying CCHS pathogenesis. Therefore, this study focused on the biochemical characterization of different PHOX 2B variants, such as a variant containing the correct C‐terminal (20 alanines) stretch, one of the most frequent polyalanine expansions (+7 alanines), and a variant lacking the complete alanine stretch (0 alanines). Comparison of the different variants by a multidisciplinary approach based on different methodologies (including circular dichroism, spectrofluorimetry, light scattering, and Atomic Force Microscopy studies) highlighted the propensity to aggregate for the PHOX 2B variant containing the polyalanine expansion (+7‐alanines), especially in the presence of DNA , while the 0‐alanines variant resembled the protein with the correct polyalanine length. Moreover, and unexpectedly, the formation of fibrils was revealed only for the pathological variant, suggesting a plausible role of such fibrils in the insurgence of CCHS .