title: Crystal structure of an intramolecular chaperone mediating triple-beta-helix folding.
abstract: 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.
authors.affiliation: Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Göttingen, Germany.
authors.forename: Eike C
authors.initials: EC
authors.lastname: Schulz
authors.forename: Achim
authors.initials: A
authors.lastname: Dickmanns
authors.forename: Henning
authors.initials: H
authors.lastname: Urlaub
authors.forename: Andreas
authors.initials: A
authors.lastname: Schmitt
authors.forename: Martina
authors.initials: M
authors.lastname: Mühlenhoff
authors.forename: Katharina
authors.initials: K
authors.lastname: Stummeyer
authors.forename: David
authors.initials: D
authors.lastname: Schwarzer
authors.forename: Rita
authors.initials: R
authors.lastname: Gerardy-Schahn
authors.forename: Ralf
authors.initials: R
authors.lastname: Ficner
mesh_terms: D017103:Bacillus Phages / Q000737:chemistry*; D003090:Coliphages / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism*; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D018832:Molecular Chaperones; D014764:Viral Proteins