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The cel4 gene of Agaricus bisporus encodes a beta-mannanase.

ABSTRACT: Mannases have industrial uses in food and pulp industries, and their regulation may influence development of the mushrooms of commercially important basidiomycetes. We expressed an Agaricus bisporus cel4 cDNA, which encodes a mannanase, in Saccharomyces cerevisiae and Pichia pastoris. CEL4 had no detectable activity on cellulose or xylan. This gene is the first isolated from this economically important fungus to encode a mannanase. P. pastoris secreted about three times more CEL4 than S. cerevisiae. The removal of the cellulose-binding domain of CEL4 lowered the secreted specific activity by P. pastoris by approximately 97%. The genomic sequence of cel4 was isolated by screening a cosmid library of A. bisporus C54-carb8. The open reading frame was interrupted by 12 introns. The level of extracellular CEL4 increases dramatically at the postharvest stage in compost extracts of A. bisporus fruiting cultures. In laboratory liquid cultures of A. bisporus, the activity of CEL4 detected in the culture filtrate reached a maximum after 21 days. The levels of CEL4 broadly mirrored the levels of enzyme activity. In the Solka floc-bound mycelium, CEL4 protein showed a maximum after 2 to 3 weeks of culture and then declined. Changes in CEL4 activity during fruiting-body development suggest that hemicellulose utilization plays an important role in sporophore formation. The availability of the cloned gene will further studies of compost decomposition and the extracellular enzymes that fungi deploy in this process.

SUBMITTER: Tang CM

PROVIDER: S-EPMC92870 | biostudies-literature | 2001 May

REPOSITORIES: biostudies-literature

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The cel4 gene of Agaricus bisporus encodes a beta-mannanase.

Tang C M CM Waterman L D LD Smith M H MH Thurston C F CF

Applied and environmental microbiology 20010501 5

Mannases have industrial uses in food and pulp industries, and their regulation may influence development of the mushrooms of commercially important basidiomycetes. We expressed an Agaricus bisporus cel4 cDNA, which encodes a mannanase, in Saccharomyces cerevisiae and Pichia pastoris. CEL4 had no detectable activity on cellulose or xylan. This gene is the first isolated from this economically important fungus to encode a mannanase. P. pastoris secreted about three times more CEL4 than S. cerevis ...[more]

PMID: 11319115

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Project description:Agaricus bisporus is a soil-inhabiting fungus which is cultivated for production of white button mushrooms. A disease of A. bisporus has been previously described with a range of disease symptoms (yield loss, pinning delay, cap distortions and cap browning) which has been given collective name of “Mushroom Virus X” (MVX). The causes of this disease are not clear however prior to this research an association was found between the disease and double-stranded RNA molecules in the mushroom fruitbodies. The experiment was designed to examine causes and host responses of the disease causing the Brown Cap symptom in the cultivated mushroom A. bisporus. This microarray experiment was performed before the Agaricus bisporus genome was sequenced. The gene sequences used to design probes were from known and novel A. bisporus sequences and sequences of transcript fragments identified by Suppression Subtractive Hybridization of non-symptomatic and virus-diseased A. bisporus mushroom fruitbodies. The A. bisporus mushroom fruitbodies were grown on composted wheat straw using commercial cultivation procedures. The gene expression comparison was made of RNA isolated from 32 mushroom fruitbodies (Agaricus bisporus) samples: 20 samples from 5 separate virus-infected commercial mushroom farms with crops displaying the brown symptom (4 replicate samples per farm) and 12 samples from a non-infected crop grown at the University of Warwick. The precise composition of the viral load was the subject of this and future research/papers. Abstract of Manuscript submitted to Applied and Environmental Microbiology: Characterizing the viral agents causing brown cap mushroom disease of Agaricus bisporus by Daniel Eastwood, Julian Green, Helen Grogan, and Kerry Burton (Paper #AEM01093-15). The symptoms of viral infections of fungi range from cryptic to severe but there is little knowledge of the factors involved in this transition of fungal/viral interactions. Brown Cap Mushroom Disease of the cultivated Agaricus bisporus is economically important and represents a model system to describe this transition. Differentially expressed transcript fragments between mushrooms showing the symptoms of Brown Cap Mushroom Disease and control white non-infected mushrooms have been identified and sequenced. Ten of these RNA fragments have been found to be up-regulated over a thousand-fold between diseased and non-diseased tissue but are absent from the Agaricus bisporus genome sequence and hybridise to double-stranded RNA’s extracted from diseased tissue. We hypothesize these transcript fragments are viral and represent components of the disease-causing agent, a bipartite virus with similarities to the family Partitiviridae. The virus fragments were found at two distinct levels within infected mushrooms, at raised levels in infected, non-symptomatic, white coloured mushrooms and much greater levels (3,500-87,000 times greater) in infected mushrooms exhibiting brown colouration. In addition, differential screening revealed 9 up-regulated and 32 down-regulated host Agaricus bisporus transcripts. Chromametric analysis was able to distinguish colour differences between non-infected white mushrooms and white infected mushrooms at an early stage of mushroom growth. This method may be the basis for an ‘on-farm’ disease detection assay.

Dataset Information

The cel4 gene of Agaricus bisporus encodes a beta-mannanase.

Publications

The cel4 gene of Agaricus bisporus encodes a beta-mannanase.

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