title: Overexpression of the gene encoding GTP:mannose-1-phosphate guanyltransferase, mpg1, increases cellular GDP-mannose levels and protein mannosylation in Trichoderma reesei.
abstract: To elucidate the regulation and limiting factors in the glycosylation of secreted proteins, the mpg1 and dpm1 genes from Trichoderma reesei (Hypocrea jecorina) encoding GTP:alpha-D-mannose-1-phosphate guanyltransferase and dolichyl phosphate mannose synthase (DPMS), respectively, were overexpressed in T. reesei. No significant increases were observed in DPMS activity or protein secretion in dpm1-overexpressing transformants, whereas overexpression of mpg1 led to a twofold increase in GDP-mannose (GDPMan) levels. GDPMan was effectively utilized by mannnosyltransferases and resulted in hypermannosylation of secreted proteins in both N and O glycosylation. Overexpression of the mpg1 gene also increased the transcription of the dpm1 gene and DPMS activity. Our data indicate that the level of cellular GDPMan can play a major regulatory role in protein glycosylation in T. reesei.
authors.affiliation: Laboratory of Fungal Glycobiology, Institute of Biochemistry and Biophysics. Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Zakrzewska
authors.forename: Grazyna
authors.initials: G
authors.lastname: Palamarczyk
authors.forename: Hubert
authors.initials: H
authors.lastname: Krotkiewski
authors.forename: Ewa
authors.initials: E
authors.lastname: Zdebska
authors.forename: Markku
authors.initials: M
authors.lastname: Saloheimo
authors.forename: Merja
authors.initials: M
authors.lastname: Penttilä
authors.forename: Joanna S
authors.initials: JS
authors.lastname: Kruszewska
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D006031:Glycosylation; D006155:Guanosine Diphosphate Mannose / Q000032:analysis*; D008358:Mannose / Q000378:metabolism*; D009713:Nucleotidyltransferases / Q000235:genetics*; D014242:Trichoderma / Q000235:genetics* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006155:Guanosine Diphosphate Mannose; D009713:Nucleotidyltransferases; C026917:mannose 1-phosphate guanylyltransferase; D008358:Mannose