Protein folding is often mediated by molecular chaperones. Recently, a novel class of intramolecular chaperones has been identified in tailspike proteins of evolutionarily distant viruses, which require a C-terminal chaperone for correct folding. The highly homologous chaperone domains are interchangeable between pre-proteins and release themselves after protein folding. Here we report the crystal structures of two intramolecular chaperone domains in either the released or the pre-cleaved form, revealing the role of the chaperone domain in the formation of a triple-beta-helix fold. Tentacle-like protrusions enclose the polypeptide chains of the pre-protein during the folding process. After the assembly, a sensory mechanism for correctly folded beta-helices triggers a serine-lysine catalytic dyad to autoproteolytically release the mature protein. Sequence analysis shows a conservation of the intramolecular chaperones in functionally unrelated proteins sharing beta-helices as a common structural motif.
Crystal structure of an intramolecular chaperone mediating triple-beta-helix folding.,Schulz EC, Dickmanns A, Urlaub H, Schmitt A, Muhlenhoff M, Stummeyer K, Schwarzer D, Gerardy-Schahn R, Ficner R Nat Struct Mol Biol. 2010 Feb;17(2):210-5. Epub 2010 Jan 31. PMID:20118935
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.