title: Crystal structure of a Hedgehog autoprocessing domain: homology between Hedgehog and self-splicing proteins.
abstract: The approximately 25 kDa carboxy-terminal domain of Drosophila Hedgehog protein (Hh-C) possesses an autoprocessing activity that results in an intramolecular cleavage of full-length Hedgehog protein and covalent attachment of a cholesterol moiety to the newly generated amino-terminal fragment. We have identified a 17 kDa fragment of Hh-C (Hh-C17) active in the initiation of autoprocessing and report here its crystal structure. The Hh-C17 structure comprises two homologous subdomains that appear to have arisen from tandem duplication of a primordial gene. Residues in the Hh-C17 active site have been identified, and their role in Hedgehog autoprocessing probed by site-directed mutagenesis. Aspects of sequence, structure, and reaction mechanism are conserved between Hh-C17 and the self-splicing regions of inteins, permitting reconstruction of a plausible evolutionary history of Hh-C and the inteins.
authors.affiliation: Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Hall
authors.forename: J A
authors.initials: JA
authors.lastname: Porter
authors.forename: K E
authors.initials: KE
authors.lastname: Young
authors.forename: E V
authors.initials: EV
authors.lastname: Koonin
authors.forename: P A
authors.initials: PA
authors.lastname: Beachy
authors.forename: D J
authors.initials: DJ
authors.lastname: Leahy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000737:chemistry / Q000235:genetics; D053823:Hedgehog Proteins; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry*; D019154:Protein Splicing / Q000502:physiology*; D017433:Protein Structure, Secondary; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D019476:Insect Proteins; D010446:Peptide Fragments; D011506:Proteins; C077245:hh protein, Drosophila