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Coexistence of two protein folding states in the crystal structure of ribosomal protein L20
Author(s) -
Timsit Youri,
Allemand Fréderic,
Chiaruttini Claude,
Springer Mathias
Publication year - 2006
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7400803
Subject(s) - ribosomal protein , protein folding , folding (dsp implementation) , protein structure , ribosomal rna , intrinsically disordered proteins , crystallography , chemistry , biology , rna , biophysics , computational biology , biochemistry , ribosome , electrical engineering , gene , engineering
The recent finding of intrinsically unstructured proteins defies the classical structure–function paradigm. However, owing to their flexibility, intrinsically unstructured proteins generally escape detailed structural investigations. Consequently little is known about the extent of conformational disorder and its role in biological functions. Here, we present the X‐ray structure of the unbound ribosomal protein L20, the long basic amino‐terminal extension of which has been previously interpreted as fully disordered in the absence of RNA. This study provides the first detailed picture of two protein folding states trapped together in a crystal and indicates that unfolding occurs in discrete regions of the whole protein, corresponding mainly to RNA‐binding residues. The electrostatic destabilization of the long α‐helix and a structural communication between the two L20 domains are reminiscent of those observed in calmodulin. The detailed comparison of the two conformations observed in the crystal provides new insights into the role of unfolded extensions in ribosomal assembly.