Expression, purification, and analyses of glycosylation and disulfide bonds of Stereum purpureum endopolygalacturonase I in Pichia pastoris

A DyP-Type Peroxidase of Pleurotus sapidus with Alkene Cleaving Activity

Alkene cleavage is a possibility to generate aldehydes with olfactory properties for the fragrance and flavor industry. A dye-decolorizing peroxidase (DyP) of the basidiomycete Pleurotus sapidus (PsaPOX) cleaved the aryl alkene trans-anethole. The PsaPOX was semi-purified from the mycelium via FPLC, and the corresponding gene was identified. The amino acid sequence as well as the predicted tertiary structure showed typical characteristics of DyPs as well as a non-canonical Mn²⁺-oxidation site on its surface. The gene was expressed in Komagataella pfaffii GS115 yielding activities up to 142 U/L using 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) as substrate. PsaPOX exhibited optima at pH 3.5 and 40 °C and showed highest peroxidase activity in the presence of 100 µM H₂O₂ and 25 mM Mn²⁺. PsaPOX lacked the typical activity of DyPs towards anthraquinone dyes, but oxidized Mn²⁺ to Mn³⁺. In addition, bleaching of β-carotene and annatto was observed. Biotransformation experiments verified the alkene cleavage activity towards the aryl alkenes (E)-methyl isoeugenol, α-methylstyrene, and trans-anethole, which was increased almost twofold in the presence of Mn²⁺. The resultant aldehydes are olfactants used in the fragrance and flavor industry. PsaPOX is the first described DyP with alkene cleavage activity towards aryl alkenes and showed potential as biocatalyst for flavor production.

Genome and secretome of Chondrostereum purpureum correspond to saprotrophic and phytopathogenic life styles

The basidiomycete Chondrostereum purpureum (Silverleaf fungus) is a saprotroph and plant pathogen commercially used for combatting forest "weed" trees in vegetation management. However, little is known about its lignocellulose-degrading capabilities and the enzymatic machinery that is responsible for the degradative potential, and it is not yet clear to which group of wood-rot fungi it actually belongs. Here, we sequenced and analyzed the draft genome of C. purpureum (41.2 Mbp) and performed a quantitative proteomic approach during growth in submerged and solid-state cultures based on soybean meal suspension or containing beech wood supplemented with phenol-rich olive mill residues, respectively. The fungus harbors characteristic lignocellulolytic hydrolases (GH6 and GH7) and oxidoreductases (e.g. laccase, heme peroxidases). High abundance of some of these genes (e.g. 45 laccases, nine GH7) can be explained by gene expansion, e.g. identified for the laccase orthogroup ORTHOMCL11 that exhibits a total of 18 lineage-specific duplications. Other expanded genes families encode for proteins more related to a pathogenic lifestyle (e.g. protease and cytochrome P450s). The fungus responds to the presence of complex growth substrates (lignocellulose, phenolic residues) by the secretion of most of these lignocellulolytic and lignin-modifying enzymes (e.g. alcohol and aryl alcohol oxidases, laccases, GH6, GH7). Based on the genetic and enzymatic constitution, we consider the 'marasmioid' fungus C. purpureum as a 'phytopathogenic' white-rot fungus (WRF) that possesses a complex extracellular enzyme machinery to accomplish efficient lignocellulose degradation during both saprotrophic and phytopathogenic life phases.

Purification of Recombinant Glycoproteins from Pichia pastoris Culture Supernatants

Pichia pastoris is a common host organism for the production of recombinant proteins. While unglycosylated recombinant proteins derived from this yeast can be purified efficiently by only a few conventional chromatography steps, the purification of glycosylated recombinant proteins is a very challenging process due to the intrinsic feature of the yeast of hypermannosylation. The resulting vast glycosylation pattern on the recombinant target protein masks its physicochemical properties hampering a conventional downstream process. Here, we describe a fast and efficient two-step chromatography strategy, where both steps are operated in flow-through mode, to purify recombinant glycoproteins from P. pastoris culture supernatants.

BadGluc, a β-glucosidase from Bjerkandera adusta with anthocyanase properties

A glycosidase of the basidiomycete Bjerkandera adusta (BadGluc) was found in screenings to possess a strong decolorizing ability towards malvidin-3-galactoside, an anthocyanin abundant in various berry fruits. The BadGluc was purified from the culture supernatant via FPLC, and the corresponding gene was identified which showed low similarity to other characterized glucosidases. Scanning the primary sequence with PROSITE no active site motif was detected. Eventually, a specific 18 aa consensus pattern was identified manually. The active site motif possessed an undescribed sequence which was only found in a few hypothetical proteins. The corresponding gene was cloned and expressed in Pichia pastoris GS115 yielding activities up to 100 U/L using 4-nitrophenyl-β-d-glucopyranoside (pNPG) as substrate. The enzyme possessed a good temperature (70% after 1 h at 50°C) and pH stability (70% between pH 2 and 7.5), and preferably catalysed the hydrolysis of delphinidin-3-glucoside and cyanidin-3-glucoside, regardless of the position of the terminal Hexa-His tag. This novel glucosidase worked in aqueous solution as well as on pre-stained fabrics making it the first known candidate anthocyanase for applications in the detergent and food industries.

Variants of PpuLcc, a multi-dye decolorizing laccase from Pleurotus pulmonarius expressed in Pichia pastoris

A laccase of the basidiomycete Pleurotus pulmonarius (PpuLcc) possessed strong decolorizing abilities towards artificial and natural dyes. The PpuLcc was purified from the culture supernatant via FPLC, and the corresponding gene cloned and expressed in Pichia pastoris GS115. To examine the impact of the C-terminal tail region and the signal peptide on the recombinant expression of PpuLcc, a non-modified version or different truncations (-2, -5, -13 AA) of the target protein were combined with different secretion signals. Heterologous expression of codon optimized constructs resulted in extracellular activities of the PpuLcc variants of up to 7000 U L^-1 (substrate ABTS) which was six times higher than non-codon optimized constructs. In contrast to previous works, altering the C-terminal end of the protein did not influence kinetic parameters or the rate of expression. The His-Tag purified enzymes showed high temperature optima (50-70 °C) and thermo stability. All of the recombinant variants degraded triarylmethane and azo dyes. Rapid bleaching of β-carotene (E 160a) and the polyene acid norbixin (E 160b) using a laccase was found for the first time. Thus, the enzyme may be useful in decolorizing unwanted polyene pigments, for example from the processing of cheese, bakery, desserts, ice cream or coloured casings.

MULTIFUNCin: A Multifunctional Protein Cue Induces Habitat Selection by, and Predation on, Barnacles

Foundation species provide critical resources to ecological community members and are major determinants of biodiversity. The barnacle Balanus glandula is one such species and dominates space among the higher reaches on wave-swept shores. Here, we show that B. glandula produces a 199.6-kDa glycoprotein (named "MULTIFUNCin"), and following secretion, a 390-kDa homodimer in its native state. MULTIFUNCin expression is localized in the epidermis, cuticle, and new shell material. Consequently, this molecule can specify upon contact the immediate presence of a live barnacle. Shared, conserved domains place MULTIFUNCin in the α₂-macroglobulin (A2M) subgroup of the thioester-containing protein family. Although previously undescribed, MULTIFUNCin shares 78% nucleotide sequence homology with a settlement-inducing pheromone (SIP) of the barnacle, Amphibalanus amphitrite Based on this and further evidence, we propose that the two proteins are orthologues and evolved ancestrally in structural and immunological roles. More recently, they became exploited as chemical cues for con- and heterospecific organisms, alike. MULTIFUNCin and SIP both induce habitat selection (settlement) by conspecific barnacle larvae. In addition, MULTIFUNCin acts as a potent feeding stimulant to major barnacle predators (sea stars and several whelk species). Promoting immigration via settlement on the one hand, and death via predation on the other, MULTIFUNCin simultaneously mediates opposing demographic processes toward structuring both predator and prey populations. As a multifunctional protein cue, MULTIFUNCin provides valuable sensory information, conveys different messages to different species, and drives complex biotic interactions.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010

This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.

N-glycosylation site occupancy in human prostaglandin H synthases expressed in Pichia pastoris

Prostaglandin H synthases (PGHSs) are N-glycosylated membrane proteins that catalyse the committed step in prostaglandin synthesis. Unlike PGHS-2, the production of recombinant PGHS-1 in non-mammalian expression systems is complicated. The majority of the heterologous enzyme is inactive due to misfolding. Correct N-glycosylation is proposed to be obligatory for proper folding of mammalian PGHSs. In this study, human PGHS-1 and -2 (hPGHS-1 and -2) were expressed in the yeast Pichia pastoris. Recombinant hPGHS-2 was catalytically active, whereas hPGHS-1 was inactive. Accumulation of non-glycosylated hPGHSs was not observed in the crude lysate of the yeast cells. The N-glycosylation patterns of the purified recombinant proteins were characterised using nano-LC/MS/MS. The isoforms exhibited similar N-glycosylation site occupancy. The results indicate that there are more complex grounds for the inactivity of the recombinant hPGHS-1 produced in yeast.

Active suppression of EndoPG IV by ligation of the pro-sequence from Stereum purpureum Pro-EndoPG I

We attempted to inactivate endopolygaolacturonase from Stereum purpureum (EndoPG) IV of identical origin by linking the pro-sequence of S. purpureum Pro-EndoPG I to the C-terminus. The recombinant Pro-EndoPG IV, expressed in Escherichia coli, had no polygalacturonase (PG) activity, but activity was acquired after partial degradation of the pro-sequence with V8 protease, as was the case for Pro-EndoPG I. These results indicate that the pro-sequence of Pro-EndoPG I can suppress the PG activity of EndoPG IV.