title: Kex2-dependent processing of yeast K1 killer preprotoxin includes cleavage at ProArg-44.
abstract: The K1 killer toxin of Saccharomyces cerevisiae consists of 103- and 83-residue alpha and beta components whose derivation, from a 316-residue precursor preprotoxin, requires processing at the alpha N-terminus (after ProArg-44), the alpha C-terminus (after ArgArg-149) and at the beta N-terminus (after LysArg-233). These processing events occur after translocation to the Golgi and have been investigated using beta-lactamase fusions. Signal peptidase cleavage of the precursor, predicted to occur after Ala-26, was confirmed by N-terminal sequence analysis of Ala-34 and Ile-52 fusions. Cleavage at all of the other predicted processing sites, including ProArg-44, is dependent on activity of the Kex2 protease. A fourth Kex2-dependent cleavage occurs at LysArg-188. Implications for the specificity of Kex2 cleavage and preprotoxin processing are discussed.
authors.affiliation: Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester 01655.
authors.forename: Y S
authors.initials: YS
authors.lastname: Zhu
authors.forename: X Y
authors.initials: XY
authors.lastname: Zhang
authors.forename: C P
authors.initials: CP
authors.lastname: Cartwright
authors.forename: D J
authors.initials: DJ
authors.lastname: Tipper
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000378:metabolism*; D055646:Killer Factors, Yeast; D008969:Molecular Sequence Data; D009183:Mycotoxins / Q000378:metabolism*; D043484:Proprotein Convertases; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases / Q000378:metabolism*; D013381:Subtilisins
chemical_list: D005656:Fungal Proteins; D055646:Killer Factors, Yeast; D009183:Mycotoxins; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; D043484:Proprotein Convertases; D012697:Serine Endopeptidases; D013381:Subtilisins; C058751:KEX2 protein, S cerevisiae