Functions of a Glucan Synthase Gene GFGLS in Mycelial Growth and Polysaccharide Production of Grifola frondosa

Abstract

Glucan synthase (GLS) gene is known to be involved in the fungal biosynthesis of cell wall, differentiation, and growth. In the present study, a glucan synthase gene (GFGLS) in the edible mushroom Grifola frondosa with a full sequence of 5927 bp encoding a total of 1781 amino acids was cloned and characterized for the first time. GFGLSp is a membrane protein containing two large transmembrane domains connected with a hydrophilic cytoplasmic domain. With a constructed dual promoter RNA silencing vector pAN7-gfgls-dual, a GFGLS-silencing transformant iGFGLS-3 had the lowest GFGLS transcriptional expression level (26.1%) with a shorter length and thinner appearance of the mycelia, as well as decreased mycelial biomass and exo-polysaccharide production of 5.02 and 0.38 g/L, respectively. Further analysis indicated that GFGLS silence influenced slightly the monosaccharide compositions and ratios of mycelial and exo-polysaccharide. These findings suggest that GFGLS could affect mycelial growth and polysaccharide production by downregulating the glucan synthesis.

Functional Characterization and Structural Basis of the β-1,3-Glucan Synthase CMGLS from Mushroom Cordyceps militaris

“…frondosa . However, no UDP-glucose binding motif QXXRW or R/KXGG was observed in the central hydrophilic catalytic domain in CMGLSp in the present study. Similarly, no QXXRW or R/KXGG motif was found in the second glucan synthase (nominated as GFGLS2) of G.…”

“…frondosa 9006-11 was wrongly annotated as a putative termination codon, which split the full sequence of β-1,3-glucan synthase genes into four sequences (GenBank: OBZ75851.1, OBZ75850.1). Accordingly, the β-1,3-glucan synthase genes GFGLS and GFGLS2 were corrected and reannotated with the full sequence of 5927 and 5944 bp (GenBank: MK80801.9 and MN477285.1). , …”

“…In our previous study, a motif KEGG from residue 992 to 995 was also observed in the large hydrophilic catalytic domain of a glucan synthase (GFGLS) of G. frondosa 9801 . In contrast, no QXXRW or R/KXGG motif was found in another G.…”

“…crassa having a molecular mass of >200 kDa with up to 16 transmembrane helices binding the substrate UDP-glucose Grifola frondosa contained at least two genes encoding β-1,3-glucan synthases GFGLSp and GFGLS2p with the predicted molecular masses of 203.66 and 195.2 kDa, respectively. , However, the functions and the catalytic characteristics/mechanisms of β-1,3-glucan synthases in fungi and mushrooms are still bottlenecked by their extremely complex structures with multi-transmembranes and large molecular masses. Saxena et al and Farkas et al pointed out that the catalysis of glucan synthases in yeasts and fungi usually depended on their interaction of the specific binding sites with the substrate UDP-glucose. , By searching for strictly conserved amino acid residues in the glycogen synthase of several species, the conserved sequence motif QXXRW or R/KXGG in glucan synthase of S.…”

Improving Hypoxia Adaption Causes Distinct Effects on Growth and Bioactive Compounds Synthesis in an Entomopathogenic Fungus Cordyceps militaris

“…Crude polysaccharides of the transformants and WT strains were extracted using an improved water extraction method ( Cui et al, 2019 ). Briefly, the mycelial biomass was separated from the fermentation mixturesby filtration.…”