Repression of N-glycosylation triggers the unfolded protein response (UPR) and overexpression of cell wall protein and chitin in Aspergillus fumigatus

Nitrate assimilation compensates for cell wall biosynthesis in the absence of Aspergillus fumigatus phosphoglucose isomerase

Phosphoglucose isomerase (PGI) links glycolysis, the pentose phosphate pathway (PPP), and the synthesis of cell wall precursors in fungi by facilitating the reversible conversion between glucose-6-phosphate (Glc6p) and fructose-6-phosphate (Fru6P). In a previous study, we established the essential role of PGI in cell wall biosynthesis in the opportunistic human fungal pathogen Aspergillus fumigatus, highlighting its potential as a therapeutic target. In this study, we conducted transcriptomic analysis and discovered that the Δpgi mutant exhibited enhanced glycolysis, reduced PPP, and an upregulation of cell wall precursor biosynthesis pathways. Phenotypic analysis revealed defective protein N-glycosylation in the mutant, notably the absence of glycosylated virulence factors DPP V and catalase 1. Interestingly, the cell wall defects in the mutant were not accompanied by activation of the MpkA-dependent cell wall integrity (CWI) signaling pathway. Instead, nitrate assimilation was activated in the Δpgi mutant, stimulating glutamine synthesis and providing amino donors for chitin precursor biosynthesis. Blocking the nitrate assimilation pathway severely impaired the growth of the Δpgi mutant, highlighting the crucial role of nitrate assimilation in rescuing cell wall defects. This study unveils the connection between nitrogen assimilation and cell wall compensation in A. fumigatus.IMPORTANCEAspergillus fumigatus is a common and serious human fungal pathogen that causes a variety of diseases. Given the limited availability of antifungal drugs and increasing drug resistance, it is imperative to understand the fungus' survival mechanisms for effective control of fungal infections. Our previous study highlighted the essential role of A. fumigatus PGI in maintaining cell wall integrity, phosphate sugar homeostasis, and virulence. The present study further illuminates the involvement of PGI in protein N-glycosylation. Furthermore, this research reveals that the nitrogen assimilation pathway, rather than the canonical MpkA-dependent CWI pathway, compensates for cell wall deficiencies in the mutant. These findings offer valuable insights into a novel adaptation mechanism of A. fumigatus to address cell wall defects, which could hold promise for the treatment of infections.

Characterization of PcSTT3B as a Key Oligosaccharyltransferase Subunit Involved in N-glycosylation and Its Role in Development and Pathogenicity of Phytophthora capsici

Asparagine (Asn, N)-linked glycosylation is a conserved process and an essential post-translational modification that occurs on the NXT/S motif of the nascent polypeptides in endoplasmic reticulum (ER). The mechanism of N-glycosylation and biological functions of key catalytic enzymes involved in this process are rarely documented for oomycetes. In this study, an N-glycosylation inhibitor tunicamycin (TM) hampered the mycelial growth, sporangial release, and zoospore production of Phytophthora capsici, indicating that N-glycosylation was crucial for oomycete growth development. Among the key catalytic enzymes involved in N-glycosylation, the PcSTT3B gene was characterized by its functions in P. capsici. As a core subunit of the oligosaccharyltransferase (OST) complex, the staurosporine and temperature sensive 3B (STT3B) subunit were critical for the catalytic activity of OST. The PcSTT3B gene has catalytic activity and is highly conservative in P. capsici. By using a CRISPR/Cas9-mediated gene replacement system to delete the PcSTT3B gene, the transformants impaired mycelial growth, sporangial release, zoospore production, and virulence. The PcSTT3B-deleted transformants were more sensitive to an ER stress inducer TM and display low glycoprotein content in the mycelia, suggesting that PcSTT3B was associated with ER stress responses and N-glycosylation. Therefore, PcSTT3B was involved in the development, pathogenicity, and N-glycosylation of P. capsici.

GmDAD1, a Conserved Defender Against Cell Death 1 (DAD1) From Soybean, Positively Regulates Plant Resistance Against Phytophthora Pathogens

Initially identified as a mammalian apoptosis suppressor, defender against apoptotic death 1 (DAD1) protein has conserved plant orthologs acting as negative regulators of cell death. The potential roles and action mechanisms of plant DADs in resistance against Phytophthora pathogens are still unknown. Here, we cloned GmDAD1 from soybean and performed functional dissection. GmDAD1 expression can be induced by Phytophthora sojae infection in both compatible and incompatible soybean varieties. By manipulating GmDAD1 expression in soybean hairy roots, we showed that GmDAD1 transcript accumulations are positively correlated with plant resistance levels against P. sojae. Heterologous expression of GmDAD1 in Nicotiana benthamiana enhanced its resistance to Phytophthora parasitica. NbDAD1 from N. benthamiana was shown to have similar role in conferring Phytophthora resistance. As an endoplasmic reticulum (ER)-localized protein, GmDAD1 was demonstrated to be involved in ER stress signaling and to affect the expression of multiple defense-related genes. Taken together, our findings reveal that GmDAD1 plays a critical role in defense against Phytophthora pathogens and might participate in the ER stress signaling pathway. The defense-associated characteristic of GmDAD1 makes it a valuable working target for breeding Phytophthora resistant soybean varieties.

The AGC Kinase YpkA Regulates Sphingolipids Biosynthesis and Physically Interacts With SakA MAP Kinase in Aspergillus fumigatus

Sphingolipids (SL) are complex lipids and components of the plasma membrane which are involved in numerous cellular processes, as well as important for virulence of different fungal pathogens. In yeast, SL biosynthesis is regulated by the "AGC kinases" Ypk1 and Ypk2, which also seem to connect the SL biosynthesis with the cell wall integrity (CWI) and the High Osmolarity Glycerol (HOG) pathways. Here, we investigate the role of ypkA ^{Y PK1} in SL biosynthesis and its relationship with the CWI and the HOG pathways in the opportunistic human pathogen Aspergillus fumigatus. We found that ypkA is important for fungal viability, since the ΔypkA strain presented a drastically sick phenotype and complete absence of conidiation. We observed that under repressive condition, the conditional mutant niiA::ypkA exhibited vegetative growth defects, impaired germination and thermosensitivity. In addition, the ypkA loss of function caused a decrease in glycosphingolipid (GSL) levels, especially the metabolic intermediates belonging to the neutral GSL branch including dihydroceramide (DHC), ceramide (Cer), and glucosylceramide (GlcCer), but interestingly a small increase in ergosterol content. Genetic analyzes showed that ypkA genetically interacts with the MAP kinases of CWI and HOG pathways, mpkA and sakA, respectively, while only SakA physically interacts with YpkA. Our results suggest that YpkA is important for fungal survival through the regulation of GSL biosynthesis and cross talks with A. fumigatus MAP kinase pathways.

Role of Downregulation and Phosphorylation of Cofilin in Polarized Growth, MpkA Activation and Stress Response of Aspergillus fumigatus

Aspergillus fumigatus causes most of aspergillosis in clinic and comprehensive function analysis of its key protein would promote anti-aspergillosis. In a previous study, we speculated actin depolymerizing factor cofilin might be essential for A. fumigatus viability and found its overexpression upregulated oxidative response and cell wall polysaccharide synthesis of this pathogen. Here, we constructed a conditional cofilin mutant to determine the essential role of cofilin. And the role of cofilin downregulation and phosphorylation in A. fumigatus was further analyzed. Cofilin was required for the polarized growth and heat sensitivity of A. fumigatus. Downregulation of cofilin caused hyphal cytoplasmic leakage, increased the sensitivity of A. fumigatus to sodium dodecyl sulfonate but not to calcofluor white and Congo Red and farnesol, and enhanced the basal phosphorylation level of MpkA, suggesting that cofilin affected the cell wall integrity (CWI) signaling. Downregulation of cofilin also increased the sensitivity of A. fumigatus to alkaline pH and H₂O₂. Repressing cofilin expression in A. fumigatus lead to attenuated virulence, which manifested as lower adherence and internalization rates, weaker host inflammatory response and shorter survival rate in a Galleria mellonella model. Expression of non-phosphorylated cofilin with a mutation of S5A had little impacts on A. fumigatus, whereas expression of a mimic-phosphorylated cofilin with a mutation of S5E resulted in inhibited growth, increased phospho-MpkA level, and decreased pathogenicity. In conclusion, cofilin is crucial to modulating the polarized growth, stress response, CWI and virulence of A. fumigatus.

The adaptive landscape of wildtype and glycosylation-deficient populations of the industrial yeast Pichia pastoris

Background

The effects of long-term environmental adaptation and the implications of major cellular malfunctions are still poorly understood for non-model but biotechnologically relevant species. In this study we performed a large-scale laboratory evolution experiment with 48 populations of the yeast Pichia pastoris in order to establish a general adaptive landscape upon long-term selection in several glucose-based growth environments. As a model for a cellular malfunction the implications of OCH1 mannosyltransferase knockout-mediated glycosylation-deficiency were analyzed.

Results

In-depth growth profiling of evolved populations revealed several instances of genotype-dependent growth trade-off/cross-benefit correlations in non-evolutionary growth conditions. On the genome level a high degree of mutational convergence was observed among independent populations. Environment-dependent mutational hotspots were related to osmotic stress-, Rim - and cAMP signaling pathways. In agreement with the observed growth phenotypes, our data also suggest diverging compensatory mutations in glycosylation-deficient populations. High osmolarity glycerol (HOG) pathway loss-of-functions mutations, including genes such as SSK2 and SSK4, represented a major adaptive strategy during environmental adaptation. However, genotype-specific HOG-related mutations were predominantly observed in opposing environmental conditions. Surprisingly, such mutations emerged during salt stress adaptation in OCH1 knockout populations and led to growth trade-offs in non-adaptive conditions that were distinct from wildtype HOG-mutants. Further environment-dependent mutations were identified for a hitherto uncharacterized species-specific Gal4-like transcriptional regulator involved in environmental sensing.

Conclusion

We show that metabolic constraints such as glycosylation-deficiency can contribute to evolution on the molecular level, even in non-diverging growth environments. Our dataset suggests universal adaptive mechanisms involving cellular stress response and cAMP/PKA signaling but also the existence of highly species-specific strategies involving unique transcriptional regulators, improving our biological understanding of distinct Ascomycetes species.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3952-7) contains supplementary material, which is available to authorized users.

Lung eosinophil recruitment in response to Aspergillus fumigatus is correlated with fungal cell wall composition and requires γδ T cells

The differential recognition of fungal cell wall polysaccharides that program innate and adaptive immunity to the human opportunistic fungal pathogen Aspergillus fumigatus has been a focus of considerable interest. In a mouse model of fungal conidia aspiration, decreased relative levels of cell wall core carbohydrates β-1,3-glucan to chitin in A. fumigatus isolates and mutant strains were correlated with increased airway eosinophil recruitment. In addition, an increase in fungal surface chitin exposure induced by the β-1,3-glucan synthesis-targeting drug caspofungin was associated with increased murine airway eosinophil recruitment after a single challenge of conidia. The response to increased A. fumigatus chitin was associated with increased transcription of IL-17A after a single aspiration, although this cytokine was not required for eosinophil recruitment. Rather, both RAG1 and γδ T cells were required, suggesting that this subset of innate-like lymphocytes may be an important regulator of potentially detrimental type 2 immune responses to fungal inhalation and infection.

Genome sequence of Aspergillus luchuensis NBRC 4314

Awamori is a traditional distilled beverage made from steamed Thai-Indica rice in Okinawa, Japan. For brewing the liquor, two microbes, local kuro (black) koji mold Aspergillus luchuensis and awamori yeast Saccharomyces cerevisiae are involved. In contrast, that yeasts are used for ethanol fermentation throughout the world, a characteristic of Japanese fermentation industries is the use of Aspergillus molds as a source of enzymes for the maceration and saccharification of raw materials. Here we report the draft genome of a kuro (black) koji mold, A. luchuensis NBRC 4314 (RIB 2604). The total length of nonredundant sequences was nearly 34.7 Mb, comprising approximately 2,300 contigs with 16 telomere-like sequences. In total, 11,691 genes were predicted to encode proteins. Most of the housekeeping genes, such as transcription factors and N-and O-glycosylation system, were conserved with respect to Aspergillus niger and Aspergillus oryzae An alternative oxidase and acid-stable α-amylase regarding citric acid production and fermentation at a low pH as well as a unique glutamic peptidase were also found in the genome. Furthermore, key biosynthetic gene clusters of ochratoxin A and fumonisin B were absent when compared with A. niger genome, showing the safety of A. luchuensis for food and beverage production. This genome information will facilitate not only comparative genomics with industrial kuro-koji molds, but also molecular breeding of the molds in improvements of awamori fermentation.

Mapping N-linked glycosylation of carbohydrate-active enzymes in the secretome of Aspergillus nidulans grown on lignocellulose

BACKGROUND

The genus Aspergillus includes microorganisms that naturally degrade lignocellulosic biomass, secreting large amounts of carbohydrate-active enzymes (CAZymes) that characterize their saprophyte lifestyle. Aspergillus has the capacity to perform post-translational modifications (PTM), which provides an additional advantage for the use of these organisms as a host for the production of heterologous proteins. In this study, the N-linked glycosylation of CAZymes identified in the secretome of Aspergillus nidulans grown on lignocellulose was mapped.

RESULTS

Aspergillus nidulans was grown in glucose, xylan and pretreated sugarcane bagasse (SCB) for 96 h, after which glycoproteomics and glycomics were carried out on the extracellular proteins (secretome). A total of 265 proteins were identified, with 153, 210 and 182 proteins in the glucose, xylan and SCB substrates, respectively. CAZymes corresponded to more than 50 % of the total secretome in xylan and SCB. A total of 182 N-glycosylation sites were identified, of which 121 were detected in 67 CAZymes. A prevalence of the N-glyc sequon N-X-T (72.2 %) was observed in N-glyc sites compared with N-X-S (27.8 %). The amino acids flanking the validated N-glyc sites were mainly composed of hydrophobic and polar uncharged amino acids. Selected proteins were evaluated for conservation of the N-glyc sites in Aspergilli homologous proteins, but a pattern of conservation was not observed. A global analysis of N-glycans released from the proteins secreted by A. nidulans was also performed. While the proportion of N-glycans with Hex5 to Hex9 was similar in the xylan condition, a prevalence of Hex5 was observed in the SCB and glucose conditions.

CONCLUSIONS

The most common and frequent N-glycosylated motifs, an overview of the N-glycosylation of the CAZymes and the number of mannoses found in N-glycans were analyzed. There are many bottlenecks in protein production by filamentous fungi, such as folding, transport by vesicles and secretion, but N-glycosylation in the correct context is a fundamental event for defining the high levels of secretion of target proteins. A comprehensive analysis of the protein glycosylation processes in A. nidulans will assist with a better understanding of glycoprotein structures, profiles, activities and functions. This knowledge can help in the optimization of heterologous expression and protein secretion in the fungal host.

SWATH-MS Glycoproteomics Reveals Consequences of Defects in the Glycosylation Machinery

Glycan macro- and microheterogeneity have profound impacts on protein folding and function. This heterogeneity can be regulated by physiological or environmental factors. However, unregulated heterogeneity can lead to disease, and mutations in the glycosylation process cause a growing number of Congenital Disorders of Glycosylation. We systematically studied how mutations in the N-glycosylation pathway lead to defects in mature proteins using all viable Saccharomyces cerevisiae strains with deletions in genes encoding Endoplasmic Reticulum lumenal mannosyltransferases (Alg3, Alg9, and Alg12), glucosyltransferases (Alg6, Alg8, and Die2/Alg10), or oligosaccharyltransferase subunits (Ost3, Ost5, and Ost6). To measure the changes in glycan macro- and microheterogeneity in mature proteins caused by these mutations we developed a SWATH-mass spectrometry glycoproteomics workflow. We measured glycan structures and occupancy on mature cell wall glycoproteins, and relative protein abundance, in the different mutants. All mutants showed decreased glycan occupancy and altered cell wall proteomes compared with wild-type cells. Mutations in earlier mannosyltransferase or glucosyltransferase steps of glycan biosynthesis had stronger hypoglycosylation phenotypes, but glucosyltransferase defects were more severe. ER mannosyltransferase mutants displayed substantial global changes in glycan microheterogeneity consistent with truncations in the glycan transferred to protein in these strains. Although ER glucosyltransferase and oligosaccharyltransferase subunit mutants broadly showed no change in glycan structures, ost3Δ cells had shorter glycan structures at some sites, consistent with increased protein quality control mannosidase processing in this severely hypoglycosylating mutant. This method allows facile relative quantitative glycoproteomics, and our results provide insights into global regulation of site-specific glycosylation.

Comparative proteomic analyses reveal that Gnt2-mediated N-glycosylation affects cell wall glycans and protein content in Fusarium oxysporum

Protein N-glycosylation is a ubiquitous post-translational modification that contributes to appropriate protein folding, stability, functionality and localization. N-glycosylation has been identified as an important process for morphogenesis and virulence in several fungal pathogens including Fusarium oxysporum. Here we conducted comparative chemical and proteome-based analyses to better understand the physiological changes associated with protein hypo-N-glycosylation in F. oxysporum N-glycosyltransferase Gnt2-deficient mutant. The results suggest that lack of functional Gnt2 alters the size of galactofuranose chains in cell wall glycans, resulting in polysaccharides with a broad range of polymerization degrees and differential protein glycosylation patterns. Functional Gnt2 is necessary for normal conidium size and morphology and wild-type hyphal fusion rates. Hypo-N-glycosylation in ∆gnt2 mutant results in enhanced oxidative stress resistance and reduced levels of proteins involved in cell wall organization, biogenesis and remodelling. Deletion of gnt2 gene led to accumulation of trafficking vesicles at hyphal tips, reduced secretion of extracellular proteins related to detoxification of antifungal compounds and degradation of plant cell walls, and lowered extracellular polygalacturonase activity. Altogether, the results confirm that Gnt2-mediated N-glycosylation plays a crucial role in morphogenesis and virulence, and demonstrate that Gnt2 is essential for protein function, transport and relative abundance in F. oxysporum.

The genome of the myxosporean Thelohanellus kitauei shows adaptations to nutrient acquisition within its fish host

Members of Myxozoa, a parasitic metazoan taxon, have considerable detrimental effects on fish hosts and also have been associated with human food-borne illness. Little is known about their biology and metabolism. Analysis of the genome of Thelohanellus kitauei and comparative analysis with genomes of its two free-living cnidarian relatives revealed that T. kitauei has adapted to parasitism, as indicated by the streamlined metabolic repertoire and the tendency toward anabolism rather than catabolism. Thelohanellus kitauei mainly secretes proteases and protease inhibitors for nutrient digestion (parasite invasion), and depends on endocytosis (mainly low-density lipoprotein receptors-mediated type) and secondary carriers for nutrient absorption. Absence of both classic and complementary anaerobic pathways and gluconeogenesis, the lack of de novo synthesis and reduced activity in hydrolysis of fatty acids, amino acids, and nucleotides indicated that T. kitauei in this vertebrate host-parasite system has adapted to inhabit a physiological environment extremely rich in both oxygen and nutrients (especially glucose), which is consistent with its preferred parasitic site, that is, the host gut submucosa. Taking advantage of the genomic and transcriptomic information, 23 potential nutrition-related T. kitauei-specific chemotherapeutic targets were identified. This first genome sequence of a myxozoan will facilitate development of potential therapeutics for efficient control of myxozoan parasites and ultimately prevent myxozoan-induced fish-borne illnesses in humans.

The importance of connections between the cell wall integrity pathway and the unfolded protein response in filamentous fungi

In the external environment, or within a host organism, filamentous fungi experience sudden changes in nutrient availability, osmolality, pH, temperature and the exposure to toxic compounds. The fungal cell wall represents the first line of defense, while also performing essential roles in morphology, development and virulence. A polarized secretion system is paramount for cell wall biosynthesis, filamentous growth, nutrient acquisition and interactions with the environment. The unique ability of filamentous fungi to secrete has resulted in their industrial adoption as fungal cell factories. Protein maturation and secretion commences in the endoplasmic reticulum (ER). The unfolded protein response (UPR) maintains ER functionality during exposure to secretion and cell wall stress. UPR, therefore, influences secretion and cell wall homeostasis, which in turn impacts upon numerous fungal traits important to pathogenesis and biotechnology. Subsequently, this review describes the relevance of the cell wall and UPR systems to filamentous fungal pathogens or industrial microbes and then highlights interconnections between the two systems. Ultimately, the possible biotechnological applications of an enhanced understanding of such regulatory systems in combating fungal disease, or the removal of natural bottlenecks in protein secretion in an industrial setting, are discussed.

Isolate-dependent growth, virulence, and cell wall composition in the human pathogen Aspergillus fumigatus

The ubiquitous fungal pathogen Aspergillus fumigatus is a mediator of allergic sensitization and invasive disease in susceptible individuals. The significant genetic and phenotypic variability between and among clinical and environmental isolates are important considerations in host-pathogen studies of A. fumigatus-mediated disease. We observed decreased radial growth, rate of germination, and ability to establish colony growth in a single environmental isolate of A. fumigatus, Af5517, when compared to other clinical and environmental isolates. Af5517 also exhibited increased hyphal diameter and cell wall β-glucan and chitin content, with chitin most significantly increased. Morbidity, mortality, lung fungal burden, and tissue pathology were decreased in neutropenic Af5517-infected mice when compared to the clinical isolate Af293. Our results support previous findings that suggest a correlation between in vitro growth rates and in vivo virulence, and we propose that changes in cell wall composition may contribute to this phenotype.

Co-ordination between BrlA regulation and secretion of the oxidoreductase FmqD directs selective accumulation of fumiquinazoline C to conidial tissues in Aspergillus fumigatus

Aerial spores, crucial for propagation and dispersal of the Kingdom Fungi, are commonly the initial inoculum of pathogenic fungi. Natural products (secondary metabolites) have been correlated with fungal spore development and enhanced virulence in the human pathogen Aspergillus fumigatus but mechanisms for metabolite deposition in the spore are unknown. Metabolomic profiling of A. fumigatus deletion mutants of fumiquinazoline (Fq) cluster genes reveal that the first two products of the Fq cluster, FqF and FqA, are produced to comparable levels in all fungal tissues but the final enzymatically derived product, FqC, predominantly accumulates in the fungal spore. Loss of the sporulation-specific transcription factor, BrlA, yields a strain unable to produce FqA or FqC. Fluorescence microscopy showed FmqD, the oxidoreductase required to generate FqC, was secreted via the Golgi apparatus to the cell wall in an actin-dependent manner. In contrast, all other members of the Fq pathway including the putative transporter, FmqE - which had no effect on Fq biosynthesis - were internal to the hyphae. The co-ordination of BrlA-mediated tissue specificity with FmqD secretion to the cell wall presents a previously undescribed mechanism to direct localization of specific secondary metabolites to spores of the differentiating fungus.

OsDGL1, a homolog of an oligosaccharyltransferase complex subunit, is involved in N-glycosylation and root development in rice

A leaky rice mutant was isolated from an ethylmethane sulfonate (EMS)-mutagenized rice library based on its short root phenotype. The map-based cloning results showed that the mutant was due to a point mutation in the intron of OsDGL1 (LOC_Os07g10830), which encodes the dolichyl-diphosphooligosaccharide-protein glycosyltransferase 48 kDa subunit precursor. The mutation results in premature termination of protein synthesis. OsDGL1 is an ortholog of Arabidopsis DGL1, human OST48 and yeast WBP1, an essential protein subunit of the oligosaccharyltransferase (OST) complex, which is involved in N-glycosylation in eukaryotes. The leaky rice mutant, Osdgl1, displayed a change of matrix polysaccharides in its root cell wall, shorter root cell length, smaller root meristem and cell death in the root. Consistent with the known function of the OST complex in eukaryotes, the Osdgl1 mutation leads to a defect in N-glycosylation in the root. It was also found that reactive oxygen species (ROS) may be involved in this process.

Protein Glycosylation in Aspergillus fumigatus Is Essential for Cell Wall Synthesis and Serves as a Promising Model of Multicellular Eukaryotic Development

Glycosylation is a conserved posttranslational modification that is found in all eukaryotes, which helps generate proteins with multiple functions. Our knowledge of glycosylation mainly comes from the investigation of the yeast Saccharomyces cerevisiae and mammalian cells. However, during the last decade, glycosylation in the human pathogenic mold Aspergillus fumigatus has drawn significant attention. It has been revealed that glycosylation in A. fumigatus is crucial for its growth, cell wall synthesis, and development and that the process is more complicated than that found in the budding yeast S. cerevisiae. The present paper implies that the investigation of glycosylation in A. fumigatus is not only vital for elucidating the mechanism of fungal cell wall synthesis, which will benefit the design of new antifungal therapies, but also helps to understand the role of protein glycosylation in the development of multicellular eukaryotes. This paper describes the advances in functional analysis of protein glycosylation in A. fumigatus.