The Control of Extracellular 1,3-β-Glucanase Activity in the Basidiomycete Species QM806

Friebe, B; Holldorf, August W.

doi:10.1042/bst0030994

Cited by 9 publications

(4 citation statements)

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“…In addition to these controls at the biosynthetic level, the PL secreted by T. fusca is sensitive tQ cellobiosemediated inactivation. This extracellular enzyme inactivation appears similar to those triggered by addition of sugars to fungal cultures (18,35), but the mechanism has not been determined. The cellobiose-mediated inactivation is apparently not functional at the low cellobiose levels afforded by a recalcitrant cellulosic substrate like cotton fibers, as shown by the marked response of cotton-grown T. fusca cells to PGA.…”

Section: Resultsmentioning

confidence: 87%

Inducible thermoalkalophilic polygalacturonate lyase from Thermomonospora fusca

Stutzenberger¹

1987

J Bacteriol

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A thermostable polygalacturonate lyase (PL; EC 4.2.2.2) was secreted by Thermomonosporafusca during stationary phase in pectin-mineral salts medium at 52°C. Biosynthesis was induced by addition of pectic substances to cultures growing on glucose or cellulose but not cellobiose; the disaccharide repressed enzyme synthesis and triggered inactivation of enzyme previously secreted. The PL, purified to electrophoretic and serologic homogeneity, had a molecular size of 56 kilodaltons and an isoelectric point at pH 4.16. The amino acid composition closely resembled that of the major extracellular endoglucanases of the actinomycete. The enzyme had six cystine residues but no detectable sulfhydryl groups. It was inactivated by mild reducing agents and activated by oxygenation, indicating the necessity for disulfide bond maintenance. Temperature and pH optima for the PL reaction were 60'C and 10.45, respectively. Calcium was essential for activity but not stability; calcium dependence curves were altered by low concentrations of toxic metals. The K. for pectin increased 30,000-fold as the percent esterification (methoxylation) of that substrate was increased from 0 to 60%. The size of the minimal susceptible site for PL attack on the pectin molecule was calculated as being equivalent to 10 unesterified residues, based on the correlation of Km values at various degrees of esterification with the percentage of cleavable bonds predicted by a random-number-generating computer program.The obligately thermophilic actinomycetes play an important role in the decomposition of organic compounds in composting plant materials (28). The Thermomonospora species are prominent within this group; these species are primarily carbohydrate-degrading actinomycetes which can use a wide range of plant sugars and polymeric carbohydrates (but not proteins or amino acids) as carbon and energy sources (13,14). The genus includes at least five monosporic actinomycete species able to grow at high temperature and pH. In this regard, T. fusca appears to be the hardiest, growing in a pH range from 6 to 12 and at temperatures from 35 to 60°C (30). Although the amylase and cellulases of this genus have been characterized (9, 19), their extracellular pectinolytic enzymes have not. Such a study would be relevant to their decompositional ability, since plant biomass contains up to 15% pectin (4, 40), and the action of pectinolytic enzyme renders other polysaccharide components in plant cell walls more susceptible to hydrolysis (3). This is the first report to describe the induction, purification, and characterization of an extracellular polygalacturonate lyase (PL; EC 4.2.2.2) from a thermophilic actinomycete. MATERIALS AND METHODSStrain. The strain used in this study was originally identified as Thermomonospora curvata (37). On the basis of cell wall analysis and phage typing, it has been tentatively reclassified as T. fusca. Stock cultures were maintained as frozen, 10-fold-concentrated cell suspensions from lateexponential-phase glucose-grown cultures.Gro...

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Section: Resultsmentioning

confidence: 87%

Inducible thermoalkalophilic polygalacturonate lyase from Thermomonospora fusca

Stutzenberger¹

1987

J Bacteriol

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“…Often, derepression will occur when the repressing carbon source is utilized, resulting in exocellular β‐glucanase detection (Stone & Clarke, 1992; Pitson et al , 1993), an event with possible survival functions in fungi, which may require cell wall glucan mobilization and degradation of storage reserve materials (Reese, 1977; Santos et al , 1977; Santamaria et al , 1978; Pitson et al , 1993). However, glucose may not only lead to catabolite repression but also to a deactivation of existing β‐glucanases, as reported in the Basidiomycete QM806 (Friebe & Holldorf, 1975). In S. glucanicum evidence was produced to support the product inhibition of its β‐(1,3)‐glucanase by glucose (Rapp, 1989).…”

Section: Regulation Of Synthesis Of Fungal β‐Glucanasesmentioning

confidence: 82%

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

et al. 2007

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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).

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“…Further work will be necessary to examine this suggestion. Other examples are known in this fungus and others of extracellular systems responsible for inactivation of excreted enzymes (Wood, 1980 ;Friebe & Holldorf, 1975).…”

Section: Discussionmentioning

confidence: 99%

Production and Regulation of Extracellular Endocellulase by Agaricus bisporus

Manning

Wood

1983

Microbiology

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1839Extracellular endocellulase production by Agaricus bisporus closely paralleled mycelial growth in cultures containing microcrystalline cellulose. The enzyme was induced by various celluloses and cellobiose. In the presence of a cellulose inducer glucose and cellobiose repressed production of the enzyme. Endocellulase activity in culture filtrates was inversely related to cellulose concentration in the culture. In high concentrations of cellulose the activity of free enzyme was low. Evidence was obtained for the existence of two forms of endocellulase activity. One form adsorbed strongly to cellulose and was predominant in cultures low in cellulose. In cultures with a high cellulose content a non-adsorbable form of the enzyme was more abundant. The regulation of the appearance of free enzyme in relation to cellulose content and enzyme adsorption is discussed.

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The Control of Extracellular 1,3-β-Glucanase Activity in the Basidiomycete Species QM806

Cited by 9 publications

References 0 publications

Inducible thermoalkalophilic polygalacturonate lyase from Thermomonospora fusca

Inducible thermoalkalophilic polygalacturonate lyase from Thermomonospora fusca

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

Production and Regulation of Extracellular Endocellulase by Agaricus bisporus

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