Changes in N-acetyl galactosaminoglycan deacetylase levels during growth of Neurospora crassa: effect of L-sorbose on enzyme production

Jorge, João Atı́lio; Almeida, Elzira Maria de; Polizeli, Maria de Lourdes Teixeira de Moraes; Terenzi, Héctor Francisco

doi:10.1002/(sici)1521-4028(199912)39:5/6<337::aid-jobm337>3.3.co;2-7

Cited by 4 publications

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“…The degree of deacetylation of A. fumigatus GAG is not known, however, analysis of the GAG from Neurospora crassa found that the polymer has between 30 and 70% deacetylated galactosamine depending on the growth conditions. In N. crassa, deacetylation was correlated with the level of expression of a deacetylase [39][40][41] . Recently, it was shown that Aspergillus oryzae produces GAG with a degree of deacetylation near 50% 42 .…”

Section: Agd3 Contains a Unique Carbohydrate Binding Module (Cbm)mentioning

confidence: 99%

Structural and biochemical characterization of the exopolysaccharide deacetylase Agd3 required for Aspergillus fumigatus biofilm formation

et al. 2020

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The exopolysaccharide galactosaminogalactan (GAG) is an important virulence factor of the fungal pathogen Aspergillus fumigatus. Deletion of a gene encoding a putative deacetylase, Agd3, leads to defects in GAG deacetylation, biofilm formation, and virulence. Here, we show that Agd3 deacetylates GAG in a metal-dependent manner, and is the founding member of carbohydrate esterase family CE18. The active site is formed by four catalytic motifs that are essential for activity. The structure of Agd3 includes an elongated substrate-binding cleft formed by a carbohydrate binding module (CBM) that is the founding member of CBM family 87. Agd3 homologues are encoded in previously unidentified putative bacterial exopolysaccharide biosynthetic operons and in other fungal genomes.

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Section: Agd3 Contains a Unique Carbohydrate Binding Module (Cbm)mentioning

confidence: 99%

Structural and biochemical characterization of the exopolysaccharide deacetylase Agd3 required for Aspergillus fumigatus biofilm formation

et al. 2020

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“…The location and percentage of deacetylation have not been determined to date, but this modification is required for biofilm formation and GAG adherence (8). Production of exopolysaccharides containing ␣-1,4 -linked GalNAc and galactosamine (GalN) have also been confirmed in non-Aspergillus spp., including Neurospora crassa, Penicillium frequentans, Paecilomyces sp., and Trichosporon asahii (6,(12)(13)(14)(15). These GAG-like polymers were found to be involved in adherence to surfaces or flocculation depending on the species, suggesting that GAG-like galactosamine-containing polymers are utilized by a variety of fungi and may be of importance in agriculture and food industries, as well as human health (12,14,15).…”

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confidence: 99%

Ega3 from the fungal pathogen Aspergillus fumigatus is an endo-α-1,4-galactosaminidase that disrupts microbial biofilms

Bamford

Mauff

Subramanian

et al. 2019

Journal of Biological Chemistry

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Edited by Gerald W. HartAspergillus fumigatus is an opportunistic fungal pathogen that causes both chronic and acute invasive infections. Galactosaminogalactan (GAG) is an integral component of the A. fumigatus biofilm matrix and a key virulence factor. GAG is a heterogeneous linear ␣-1,4 -linked exopolysaccharide of galactose and GalNAc that is partially deacetylated after secretion. A cluster of five co-expressed genes has been linked to GAG biosynthesis and modification. One gene in this cluster, ega3, is annotated as encoding a putative ␣-1,4-galactosaminidase belonging to glycoside hydrolase family 114 (GH114). Herein, we show that recombinant Ega3 is an active glycoside hydrolase that disrupts GAG-dependent A. fumigatus and Pel polysaccharide-dependent Pseudomonas aeruginosa biofilms at nanomolar concentrations. Using MS and functional assays, we demonstrate that Ega3 is an endo-acting ␣-1,4-galactosaminidase whose activity depends on the conserved acidic residues, Asp-189 and Glu-247. X-ray crystallographic structural analysis of the apo Ega3 and an Ega3-galactosamine complex, at 1.76 and 2.09 Å resolutions, revealed a modified (␤/␣) 8 -fold with a deep electronegative cleft, which upon ligand binding is capped to form a tunnel. Our structural analysis coupled with in silico docking studies also uncovered the molecular determinants for galactosamine specificity and substrate binding at the ؊2 to ؉1 binding subsites. The findings in this study increase the structural and mechanistic understanding of the GH114 family, which has >600 members encoded by plant and opportunistic human pathogens, as well as in industrially used bacteria and fungi.

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“…Production of the EPSs containing α-1,4 linked GalNAc and GalN has also been reported in a few non-Aspergillus ascomycete fungi such as Neurospora crassa, Penicillium frequentans and Paecilomyces sp. [21][22][23], and the basidiomycete Trichosporon asahii [11]. Until this study, biological effects of GAG have not been reported in divergent fungal species apart from Aspergilli.…”

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confidence: 98%

Conservative production of galactosaminogalactan in Metarhizium is responsible for appressorium mucilage production and topical infection of insect hosts

et al. 2021

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The exopolysaccharide galactosaminogalactan (GAG) has been well characterized in Aspergilli, especially the human pathogen Aspergillus fumigatus. It has been found that a five-gene cluster is responsible for GAG biosynthesis in Aspergilli to mediate fungal adherence, biofilm formation, immunosuppression or induction of host immune defences. Herein, we report the presence of the conserved GAG biosynthetic gene cluster in the insect pathogenic fungus Metarhizium robertsii to mediate either similar or unique biological functions. Deletion of the gene cluster disabled fungal ability to produce GAG on germ tubes, mycelia and appressoria. Relative to the wild type strain, null mutant was impaired in topical infection but not injection of insect hosts. We found that GAG production by Metarhizium is partially acetylated and could mediate fungal adherence to hydrophobic insect cuticles, biofilm formation, and penetration of insect cuticles. In particular, it was first confirmed that this exopolymer is responsible for the formation of appressorium mucilage, the essential extracellular matrix formed along with the infection structure differentiation to mediate cell attachment and expression of cuticle degrading enzymes. In contrast to its production during A. fumigatus invasive growth, GAG is not produced on the Metarhizium cells harvested from insect hemocoels; however, the polymer can glue germ tubes into aggregates to form mycelium pellets in liquid culture. The results of this study unravel the biosynthesis and unique function of GAG in a fungal system apart from the aspergilli species.

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Changes in N-acetyl galactosaminoglycan deacetylase levels during growth of Neurospora crassa: effect of L-sorbose on enzyme production

Cited by 4 publications

References 0 publications

Structural and biochemical characterization of the exopolysaccharide deacetylase Agd3 required for Aspergillus fumigatus biofilm formation

Structural and biochemical characterization of the exopolysaccharide deacetylase Agd3 required for Aspergillus fumigatus biofilm formation

Ega3 from the fungal pathogen Aspergillus fumigatus is an endo-α-1,4-galactosaminidase that disrupts microbial biofilms

Conservative production of galactosaminogalactan in Metarhizium is responsible for appressorium mucilage production and topical infection of insect hosts

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