Regulation of cellulase gene expression in the filamentous fungus Trichoderma reesei

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Abstract

Basic features of regulation of expression of the genes encoding the cellulases of the filamentous fungus Trichoderma reesei QM9414, the genes cbh1 and cbh2 encoding cellobiohydrolases and the genes egl1, egl2 and egl5 encoding endoglucanases, were studied at the mRNA level. The cellulase genes were coordinately expressed under all conditions studied, with the steady- state mRNA levels of cbh1 being the highest. Solka floc cellulose and the disaccharide sophorose induced expression to almost the same level. Moderate expression was observed when cellobiose or lactose was used as the carbon source. It was found that glycerol and sorbitol do not promote expression but, unlike glucose, do not inhibit it either, because the addition of 1 to 2 mM sophorose to glycerol or sorbitol cultures provokes high cellulase expression levels. These carbon sources thus provide a useful means to study cellulase regulation without significantly affecting the growth of the fungus. RNA slot blot experiments showed that no expression could be observed on glucose-containing medium and that high glucose levels abolish the inducing effect of sophorose. The results clearly show that distinct and clear-cut mechanisms of induction and glucose repression regulate cellulase expression in an actively growing fungus. However, derepression of cellulase expression occurs without apparent addition of an inducer once glucose has been depleted from the medium. This expression seems not to arise simply from starvation, since the lack of carbon or nitrogen as such is not sufficient to trigger significant expression.

Original languageEnglish
Pages (from-to)1298-1306
Number of pages9
JournalApplied and Environmental Microbiology
Volume63
Issue number4
Publication statusPublished - 1 Jan 1997
MoE publication typeA1 Journal article-refereed

Fingerprint

Trichoderma reesei
Trichoderma
Cellulase
Gene Expression Regulation
endo-1,4-beta-glucanase
gene expression
glucose
Fungi
fungus
fungi
Glucose
gene
Carbon
Sorbitol
sorbitol
carbon
Glycerol
glycerol
disaccharide
Cellulose 1,4-beta-Cellobiosidase

Keywords

  • Cellulase
  • cellulose
  • disaccharide
  • fungi
  • Hypocrea jecorina
  • Trichoderma
  • glucan synthase
  • glucose
  • Glycerol
  • lactose

Cite this

@article{6977ff3c36744f7cb209da063f40e790,
title = "Regulation of cellulase gene expression in the filamentous fungus Trichoderma reesei",
abstract = "Basic features of regulation of expression of the genes encoding the cellulases of the filamentous fungus Trichoderma reesei QM9414, the genes cbh1 and cbh2 encoding cellobiohydrolases and the genes egl1, egl2 and egl5 encoding endoglucanases, were studied at the mRNA level. The cellulase genes were coordinately expressed under all conditions studied, with the steady- state mRNA levels of cbh1 being the highest. Solka floc cellulose and the disaccharide sophorose induced expression to almost the same level. Moderate expression was observed when cellobiose or lactose was used as the carbon source. It was found that glycerol and sorbitol do not promote expression but, unlike glucose, do not inhibit it either, because the addition of 1 to 2 mM sophorose to glycerol or sorbitol cultures provokes high cellulase expression levels. These carbon sources thus provide a useful means to study cellulase regulation without significantly affecting the growth of the fungus. RNA slot blot experiments showed that no expression could be observed on glucose-containing medium and that high glucose levels abolish the inducing effect of sophorose. The results clearly show that distinct and clear-cut mechanisms of induction and glucose repression regulate cellulase expression in an actively growing fungus. However, derepression of cellulase expression occurs without apparent addition of an inducer once glucose has been depleted from the medium. This expression seems not to arise simply from starvation, since the lack of carbon or nitrogen as such is not sufficient to trigger significant expression.",
keywords = "Cellulase, cellulose, disaccharide, fungi, Hypocrea jecorina, Trichoderma, glucan synthase, glucose, Glycerol, lactose",
author = "Marja Ilm{\'e}n and Anu Saloheimo and Onnela, {Maija Leena} and Penttil{\"a}, {Merja E.}",
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Regulation of cellulase gene expression in the filamentous fungus Trichoderma reesei. / Ilmén, Marja; Saloheimo, Anu; Onnela, Maija Leena; Penttilä, Merja E.

In: Applied and Environmental Microbiology, Vol. 63, No. 4, 01.01.1997, p. 1298-1306.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Regulation of cellulase gene expression in the filamentous fungus Trichoderma reesei

AU - Ilmén, Marja

AU - Saloheimo, Anu

AU - Onnela, Maija Leena

AU - Penttilä, Merja E.

PY - 1997/1/1

Y1 - 1997/1/1

N2 - Basic features of regulation of expression of the genes encoding the cellulases of the filamentous fungus Trichoderma reesei QM9414, the genes cbh1 and cbh2 encoding cellobiohydrolases and the genes egl1, egl2 and egl5 encoding endoglucanases, were studied at the mRNA level. The cellulase genes were coordinately expressed under all conditions studied, with the steady- state mRNA levels of cbh1 being the highest. Solka floc cellulose and the disaccharide sophorose induced expression to almost the same level. Moderate expression was observed when cellobiose or lactose was used as the carbon source. It was found that glycerol and sorbitol do not promote expression but, unlike glucose, do not inhibit it either, because the addition of 1 to 2 mM sophorose to glycerol or sorbitol cultures provokes high cellulase expression levels. These carbon sources thus provide a useful means to study cellulase regulation without significantly affecting the growth of the fungus. RNA slot blot experiments showed that no expression could be observed on glucose-containing medium and that high glucose levels abolish the inducing effect of sophorose. The results clearly show that distinct and clear-cut mechanisms of induction and glucose repression regulate cellulase expression in an actively growing fungus. However, derepression of cellulase expression occurs without apparent addition of an inducer once glucose has been depleted from the medium. This expression seems not to arise simply from starvation, since the lack of carbon or nitrogen as such is not sufficient to trigger significant expression.

AB - Basic features of regulation of expression of the genes encoding the cellulases of the filamentous fungus Trichoderma reesei QM9414, the genes cbh1 and cbh2 encoding cellobiohydrolases and the genes egl1, egl2 and egl5 encoding endoglucanases, were studied at the mRNA level. The cellulase genes were coordinately expressed under all conditions studied, with the steady- state mRNA levels of cbh1 being the highest. Solka floc cellulose and the disaccharide sophorose induced expression to almost the same level. Moderate expression was observed when cellobiose or lactose was used as the carbon source. It was found that glycerol and sorbitol do not promote expression but, unlike glucose, do not inhibit it either, because the addition of 1 to 2 mM sophorose to glycerol or sorbitol cultures provokes high cellulase expression levels. These carbon sources thus provide a useful means to study cellulase regulation without significantly affecting the growth of the fungus. RNA slot blot experiments showed that no expression could be observed on glucose-containing medium and that high glucose levels abolish the inducing effect of sophorose. The results clearly show that distinct and clear-cut mechanisms of induction and glucose repression regulate cellulase expression in an actively growing fungus. However, derepression of cellulase expression occurs without apparent addition of an inducer once glucose has been depleted from the medium. This expression seems not to arise simply from starvation, since the lack of carbon or nitrogen as such is not sufficient to trigger significant expression.

KW - Cellulase

KW - cellulose

KW - disaccharide

KW - fungi

KW - Hypocrea jecorina

KW - Trichoderma

KW - glucan synthase

KW - glucose

KW - Glycerol

KW - lactose

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M3 - Article

VL - 63

SP - 1298

EP - 1306

JO - Applied and Environmental Microbiology

JF - Applied and Environmental Microbiology

SN - 0099-2240

IS - 4

ER -