title: Activation and processing of non-anchored yapsin 1 (Yap3p).
abstract: A C-terminally truncated form of yapsin 1 (yeast aspartic protease 3), the first member of the novel sub-class of aspartic proteases with specificity for basic residues (designated the Yapsins), was overexpressed and purified to apparent homogeneity, yielding approximately 1 microg of yapsin 1/g of wet yeast. N-terminal amino acid analysis of the purified protein confirmed that the propeptide was absent and that the mature enzyme began at Ala68. The mature enzyme was shown to be composed of approximately equimolar amounts of two subunits, designated alpha and beta, that were associated to each other by a disulfide bond. C-terminally truncated proyapsin 1 was also expressed in the baculovirus/Sf9 insect cell expression system and secreted as a zymogen that could be activated upon incubation at an acidic pH with an optimum at approximately 4.0. When expressed without its pro-region, it was localized intracellularly and lacked activity, indicating that the pro-region was required for the correct folding of the enzyme. The activation of proyapsin 1 in vitro exhibited linear kinetics and generated an intermediate form of yapsin 1 or pseudo-yapsin 1.
authors.affiliation: Section on Cellular Neurobiology, Laboratory of Developmental Neurobiology, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA.cawley@codon.nih.gov
authors.forename: N X
authors.initials: NX
authors.lastname: Cawley
authors.forename: V
authors.initials: V
authors.lastname: Olsen
authors.forename: C F
authors.initials: CF
authors.lastname: Zhang
authors.forename: H C
authors.initials: HC
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: Tan
authors.forename: Y P
authors.initials: YP
authors.lastname: Loh
mesh_terms: D000595:Amino Acid Sequence; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D016367:Baculoviridae / Q000235:genetics; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013379:Substrate Specificity
chemical_list: D004792:Enzyme Precursors; D005656:Fungal Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C022325:aspartic proteinase A; D016282:Aspartic Acid Endopeptidases; C499266:YPS1 protein, S cerevisiae