The solution structure of DNA-free Pax-8 paired box domain accounts for redox regulation of transcriptional activity in the Pax protein family

Luca Codutti, Hugo Van Ingen, Carlo Vascotto, Federico Fogolari, Alessandra Corazza, Gianluca Tell, Franco Quadrifoglio, Paolo Viglino, Rolf Boelens, Gennaro Esposito

Research output: Contribution to journalArticle


Pax-8 is a transcription factor belonging to the PAX genes superfamily and its crucial role has been proven both in embryo and in the adult organism. Pax-8 activity is regulated via a redox-based mechanism centered on the glutathionylation of specific cysteines in the N-terminal region (Cys 45 and Cys57). These residues belong to a highly evolutionary conserved DNA binding site: the Paired Box (Prd) domain. Crystallographic protein-DNA complexes of the homologues Pax-6 and Pax-5 showed a bipartite Prd domain consisting of two helix-turn-helix (HTH) motifs separated by an extended linker region. Here, by means of nuclear magnetic resonance, we show for the first time that the HTH motifs are largely defined in the unbound Pax-8 Prd domain. Our findings contrast with previous induced fit models, in which Pax-8 is supposed to largely fold upon DNA binding. Importantly, our data provide the structural basis for the enhanced chemical reactivity of residues Cys45 and Cys57 and explain clinical missense mutations that are not obviously related to the DNA binding interface of the paired box domain. Finally, sequence conservation suggests that our findings could be a general feature of the Pax family transcription factors.

Original languageEnglish (US)
Pages (from-to)33321-33328
Number of pages8
JournalJournal of Biological Chemistry
Issue number48
Publication statusPublished - Nov 28 2008


ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

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