title: Mutation of the protein-O-mannosyltransferase enhances secretion of the human urokinase-type plasminogen activator in Hansenula polymorpha.
abstract: Human urokinase-type plasminogen activator (uPA) is poorly secreted and aggregates in the endoplasmic reticulum of yeast cells due to inefficient folding. A screen for Hansenula polymorpha mutants with improved uPA secretion revealed a gene encoding a homologue of the Saccharomyces cerevisiae protein-O-mannosyltransferase Pmt1p. Expression of the H. polymorpha PMT1 gene (HpPMT1) abolished temperature sensitivity of the S. cerevisiae pmt1 pmt2 double mutant. As in S. cerevisiae, inactivation of the HpPMT1 gene affected electrophoretic mobility of the O-glycosylated protein, extracellular chitinase. In contrast to S. cerevisiae, disruption of HpPMT1 alone caused temperature sensitivity. Inactivation of the HpPMT1 gene decreased intracellular aggregation of uPA, suggesting that enhanced secretion of uPA was due to improvement of its folding in the endoplasmic reticulum. Unlike most of the endoplasmic reticulum membrane proteins, HpPmt1p possesses the C-terminal KDEL retention signal.
authors.affiliation: Institute of Experimental Cardiology, Cardiology Research Center, 3rd Cherepkovskaya Str. 15A, Moscow 121552, Russia. aga@cardio.ru
authors.forename: Michael O
authors.initials: MO
authors.lastname: Agaphonov
authors.forename: Sviatoslav S
authors.initials: SS
authors.lastname: Sokolov
authors.forename: Nina V
authors.initials: NV
authors.lastname: Romanova
authors.forename: Jung-Hoon
authors.initials: JH
authors.lastname: Sohn
authors.forename: So-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Tatyana S
authors.initials: TS
authors.lastname: Kalebina
authors.forename: Eui-Sung
authors.initials: ES
authors.lastname: Choi
authors.forename: Michael D
authors.initials: MD
authors.lastname: Ter-Avanesyan
mesh_terms: D000595:Amino Acid Sequence; D004721:Endoplasmic Reticulum; D015966:Gene Expression Regulation, Fungal; D006031:Glycosylation; D006801:Humans; D008364:Mannosyltransferases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010843:Pichia / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D017510:Protein Folding; D017422:Sequence Analysis, DNA; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*
chemical_list: D008364:Mannosyltransferases; C082696:protein O-mannosyltransferase; D014568:Urokinase-Type Plasminogen Activator