Biochemistry and molecular biology of exocellular fungal β-(1,3)- and β-(1,6)-glucanases

Abstract

Many fungi produce exocellular beta-glucan-degrading enzymes, the beta-glucanases including the noncellulolytic beta-(1,3)- and beta-(1,6)-glucanases, degrading beta-(1,3)- and beta-(1,6)-glucans. An ability to purify several exocellular beta-glucanases attacking the same linkage type from a single fungus is common, although unlike the beta-1,3-glucanases, production of multiple beta-1,6-glucanases is quite rare in fungi. Reasons for this multiplicity remain unclear and the multiple forms may not be genetically different but arise by posttranslational glycosylation or proteolytic degradation of the single enzyme. How their synthesis is regulated, and whether each form is regulated differentially also needs clarifying. Their industrial potential will only be realized when the genes encoding them are cloned and expressed in large quantities. This review considers what is known in molecular terms about their multiplicity of occurrence, regulation of synthesis and phylogenetic diversity. It discusses how this information assists in understanding their functions in the fungi producing them. It deals largely with exocellular beta-glucanases which here refers to those recoverable after the cells are removed, since those associated with fungal cell walls have been reviewed recently by Adams (2004). It also updates the earlier review by Pitson et al. (1993).

The 74-Kilodalton Immunodominant Antigen of the Pathogenic Oomycete Pythium insidiosum Is a Putative Exo-1,3-ß-Glucanase

“…Glucanases are an interesting group of hydrolytic enzymes that are present in many organisms, including fungi (2,22,33). Glucans are major cell wall components that give strength and rigidity to fungal cells, and fungal glucanase hydrolytic activity is necessary in order to remodel the cell wall for hyphal elongation or growth (2,22,33). Although putative glucanases have been identified in some oomycetes (8,23), little is know about their biological and pathological roles.…”

“…In spite of this error in the sequence prediction by the MS analysis, the proteomic, molecular genetic, and bioinformatic evidence consistently supports the conclusion that the 74-kDa protein of P. insidiosum is an exo-1,3-ß-glucanase. Glucanases are an interesting group of hydrolytic enzymes that are present in many organisms, including fungi (2,22,33). Glucans are major cell wall components that give strength and rigidity to fungal cells, and fungal glucanase hydrolytic activity is necessary in order to remodel the cell wall for hyphal elongation or growth (2,22,33).…”

Purification, characterization and synergism in autolysis of a group of 1,3-β-glucan hydrolases from the pilei of Coprinopsis cinerea fruiting bodies

“…4c). Thus, the II-4 protein was characterized as an endo-1,3-b-glucanase (ENG) (Martin et al 2007). TLC analysis also indicated that ENG lacked transglycosylation activity toward laminarioligosaccharides (Fig.…”

Diversity in Paracoccidioides brasiliensis . The PbGP43 gene as a genetic marker

“…Purified gp43 and culture supernatants enriched for the glycoprotein were, however, negative for exo-glucanase activity when tested against laminarin or p-nitrophenyl-b-glucoside [24]. That has been attributed to the lack of a consensus NEP among b-1,3 as well as b-1, 6-glucanases [61], which is NKP in gp43 sequences from all isolates analyzed so far [23,46]. While the involvement of the NEP site in catalysis has been proven in C. albicans [62,63], in the closely related H. capsulatum and B. dematitidis databases (http:// genome.wustl.edu) sequences almost 60% identical to gp43 have been found where NEP is also present.…”