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Featured researches published by Marleen Maras.


Glycoconjugate Journal | 1999

Filamentous fungi as production organisms for glycoproteins of bio-medical interest

Marleen Maras; I. van Die; Roland Contreras; C.A.M.J.J. van den Hondel

Filamentous fungi are commonly used in the fermentation industry for large scale production of glycoproteins. Several of these proteins can be produced in concentrations up to 20–40 g per litre. The production of heterologous glycoproteins is at least one or two orders of magnitude lower but research is in progress to increase the production levels. In the past years the structure of protein-linked carbohydrates of a number of fungal proteins has been elucidated, showing the presence of oligo-mannosidic and high-mannose chains, sometimes with typical fungal modifications. A start has been made to engineer the glycosylation pathway in filamentous fungi to obtain strains that show a more mammalian-like type of glycosylation. This mini review aims to cover the current knowledge of glycosylation in filamentous fungi, and to show the possibilities to produce glycoproteins with these organisms with a more mammalian-like type of glycosylation for research purposes or pharmaceutical applications


Journal of Biotechnology | 2000

Molecular cloning and enzymatic characterization of a Trichoderma reesei 1,2-α-d-mannosidase

Marleen Maras; Nico Callewaert; Kathleen Piens; Marc Claeyssens; Wim Martinet; Sylviane Dewaele; Hans Contreras; Isabelle Dewerte; Merja Penttilä; Roland Contreras

Abstract A cDNA encoding 1,2-α- d -mannosidase mds1 from Trichoderma reesei was cloned. The largest open reading frame occupied 1571 bp. The predicted sequence contains 523 amino acid residues for a calculated molecular mass of 56u2008266 Da and shows high similarity to the amino acid sequences of 1,2-α- d -mannosidases from Aspergillus saitoi and Penicillium citrinum (51.6 and 51.0% identity, respectively). T. reesei mannosidase was produced as a recombinant enzyme in the yeast Pichia pastoris . Replacement of the N-terminal part with the prepro-signal peptide of the Saccharomyces cerevisiae α-mating factor resulted in high amounts of secreted enzyme. A three-step purification protocol was designed and the enzymatic properties were analysed. The enzyme was characterized as a class-I mannosidase.


FEBS Letters | 1999

In vivo synthesis of complex N-glycans by expression of human N-acetylglucosaminyltransferase I in the filamentous fungus Trichoderma reesei

Marleen Maras; André De Bruyn; Wouter Vervecken; Jaana Uusitalo; Merja Penttilä; Roger Busson; Piet Herdewijn; Roland Contreras

The human N‐acetylglucosaminyltransferase I gene was introduced in the genome of Trichoderma reesei strain VTT‐D‐80133. Expression was studied after induction from the cellobiohydrolase I promoter. Successful in vivo transfer of GlcNAc was demonstrated by analyzing the neutral N‐glycans which were synthesized on cellobiohydrolase I. Final proof of the formation of GlcNAcMan5GlcNAc2 was obtained by NMR analysis.


Biotechnology Letters | 1998

Modification of the protein glycosylation pathway in the methylotrophic yeast Pichia pastoris.

Wim Martinet; Marleen Maras; Xavier Saelens; Willy Min Jou; Roland Contreras

Abstractα-1,2-Mannosidase from Trichoderma reesei was used to modify the N-linked glycosylation pathway of the methylotrophic yeast Pichia pastoris. Expression of foreign influenza glycoproteins with more extensively processed N-linked oligosaccharides was observed when α-1,2-mannosidase was secreted in the culture medium. However, intracellular removal of mannose residues may stimulate mannosyltransferase activity and leads to hyperglycosylation. [3H]Mannose suicide selection or high concentrations of orthovanadate, commonly used to isolate glycosylation mutants of Saccharomyces cerevisiae, had no profound effect on Pichia pastoris.


FEBS Journal | 1999

Protection of mice against a lethal influenza virus challenge after immunization with yeast‐derived secreted influenza virus hemagglutinin

Xavier Saelens; Peter Vanlandschoot; Wim Martinet; Marleen Maras; Sabine Neirynck; Roland Contreras; Walter Fiers; Willy Min Jou


Kubicek, C.P. & Harman, G.E. (eds.), 'Trichoderma and Gliocladium. Vol. 1. Basic Biology, Taxonomy and Genetics', Taylor & Francis, London | 1998

Protein secretion and glycosylation in Trichoderma

G Palamarczyk; Marleen Maras; Roland Contreras; J Kruszewska


Analytical Biochemistry | 1997

A RADIOACTIVE ASSAY FOR SIALYLTRANSFERASE ACTIVITY USING 96-WELL MULTISCREEN FILTRATION PLATES

Wouter Laroy; Marleen Maras; Walter Fiers; Roland Contreras


Sialobiology and Other Novel Forms of Glycosylation / Edited by Y. Inoue, Y.C. Lee and F.A. Troy II. - Osaka : Gakushin, 1999. - 308 p. - ISBN 4-907773-00-5 | 1999

Structure-function analysis of human liver a 2, 6-sialyltransferase.

Wouter Laroy; Marleen Maras; Roland Contreras


Carbohydrates from Trichoderma reesei and other microorganisms : structures, biochemistry, genetics and applications | 1998

NMR techniques in the study of protein-linked carbohydrates

André De Bruyn; J Schraml; Marleen Maras; Roland Contreras; Piet Herdewijn


Carbohydrates from Trichoderma reesei and other microorganisms : structures, biochemistry, genetics and applications | 1998

Engineering of the carbohydrate moiety of fungal proteins to a mammalian type

Marleen Maras; A De Bruyn; J Schraml; Piet Herdewijn; Kathleen Piens; Marc Claeyssens; Jaana Uusitalo; Merja Penttilä; Walter Fiers; Roland Contreras

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Merja Penttilä

VTT Technical Research Centre of Finland

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J Schraml

Catholic University of Leuven

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