Publications by authors named "Raymond Verhaert"

Heterologous protein production is widely used in industrial biotechnology. However, using non-native production hosts can lead to enzymes with altered post-translational modifications, such as glycosylation. We have investigated how production in a non-native host affects the physicochemical properties and enzymatic activity of a feruloyl esterase from Myceliophthora thermophila, MtFae1a.

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Background: The yeast Komagataella phaffii, better known as Pichia pastoris, is a commonly used host for recombinant protein production. Here expression vectors are reported that address the different steps of the transcription-translation-secretion pathway of heterologous protein production.

Results: Transcription and translation enhancing elements were introduced in an expression cassette for the production of recombinant Aspergillus niger feruloyl esterase A.

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Feruloyl esterases (FAEs) are a diverse group of enzymes that specifically catalyze the hydrolysis of ester bonds between a hydroxycinnamic (e.g. ferulic) acid and plant poly- or oligosaccharides.

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4-O-Methyl-d-glucuronic acid (MeGlcA) is a side-residue of glucuronoarabinoxylan and can form ester linkages to lignin, contributing significantly to the strength and rigidity of the plant cell wall. Glucuronoyl esterases (4-O-methyl-glucuronoyl methylesterases, GEs) can cleave this ester bond, and therefore may play a significant role as auxiliary enzymes in biomass saccharification for the production of biofuels and biochemicals. GEs belong to a relatively new family of carbohydrate esterases (CE15) in the CAZy database (www.

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In filamentous fungi, most of the strategies used for the improvement of protein yields have been based on an increase in the transcript levels of a target gene. Strategies focusing at the translational level have been also described, but are far less explored. Here the 5' untranslated sequence of the glaA mRNA, a widely used expression system for the expression of recombinant proteins, was modified by the introduction of different nucleotide elements that have positive role in the translation process.

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Background: Many filamentous fungal genomes contain complex groups of multicopper oxidase (MCO) coding genes that makes them a good source for new laccases with potential biotechnological interest. A bioinformatics analysis of the Aspergillus niger ATCC 1015 genome resulted in the identification of thirteen MCO genes. Ten of them were cloned and homologously overexpressed.

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Semi-synthetic cephalosporin antibiotics belong to the top 10 of most sold drugs, and are produced from 7-aminodesacetoxycephalosporanic acid (7-ADCA). Recently new routes have been developed which allow for the production of adipyl-7-ADCA by a novel fermentation process. To complete the biosynthesis of 7-ADCA a highly active adipyl acylase is needed for deacylation of the adipyl derivative.

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Directed evolution of secreted industrial enzymes is hampered by the lack of powerful selection techniques. We have explored surface display to select for enzyme variants with improved binding performance on complex polymeric substrates. By a combination of saturation mutagenesis and phage display we selected alpha-amylase variants, which have the ability to bind starch substrate at industrially preferred low pH conditions.

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The potential of the RNA phage MS2 to accommodate extra amino acids in its major coat protein has been examined. Accordingly, a pentapeptide was encoded in the genome as an N-terminal extension. In the MS2 crystal structure, this part of the coat protein forms a loop that extends from the outer surface of the icosahedral virion.

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