Hydrogen bonds are a primary driving force for de novo protein folding. Corrigendum.

The paper by Lee et al. [(2017). Acta Cryst. D73, 955-969] is withdrawn.

We wish to withdraw the paper by Lee et al. (2017 ▸) on the crystal structure of a protein believed to have been AID (activation-induced cytidine deaminase). It has subsequently been shown that the crystal studied was of E. coli RNA-binding protein Hfq, a contaminant in the protein preparation. The associated PDB entry, 5w09, has also been made obsolete. Our conclusions regarding the critical role of proline residues in protein folding, successful folding of proteins at high pH, and hydrogen bonds as a driving force in de novo protein folding are not affected, and further details will be published elsewhere.