title: Differential regulation of the cellulase transcription factors XYR1, ACE2, and ACE1 in Trichoderma reesei strains producing high and low levels of cellulase.
abstract: Due to its capacity to produce large amounts of cellulases, Trichoderma reesei is increasingly being investigated for second-generation biofuel production from lignocellulosic biomass. The induction mechanisms of T. reesei cellulases have been described recently, but the regulation of the genes involved in their transcription has not been studied thoroughly. Here we report the regulation of expression of the two activator genes xyr1 and ace2, and the corepressor gene ace1, during the induction of cellulase biosynthesis by the inducer lactose in T. reesei QM 9414, a strain producing low levels of cellulase (low producer). We show that all three genes are induced by lactose. xyr1 was also induced by d-galactose, but this induction was independent of d-galactose metabolism. Moreover, ace1 was carbon catabolite repressed, whereas full induction of xyr1 and ace2 in fact required CRE1. Significant differences in these regulatory patterns were observed in the high-producer strain RUT C30 and the hyperproducer strain T. reesei CL847. These observations suggest that a strongly elevated basal transcription level of xyr1 and reduced upregulation of ace1 by lactose may have been important for generating the hyperproducer strain and that thus, these genes are major control elements of cellulase production.
authors.affiliation: IFP Energies nouvelles, Département Biotechnologie, 1-4 Avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Portnoy
authors.forename: Antoine
authors.initials: A
authors.lastname: Margeot
authors.forename: Verena
authors.initials: V
authors.lastname: Seidl-Seiboth
authors.forename: Stéphane
authors.initials: S
authors.lastname: Le Crom
authors.forename: Fadhel
authors.initials: F
authors.lastname: Ben Chaabane
authors.forename: Rita
authors.initials: R
authors.lastname: Linke
authors.forename: Bernhard
authors.initials: B
authors.lastname: Seiboth
authors.forename: Christian P
authors.initials: CP
authors.lastname: Kubicek
mesh_terms: D002480:Cellulase / Q000096:biosynthesis* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000378:metabolism; D007785:Lactose / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014242:Trichoderma / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D005656:Fungal Proteins; D014157:Transcription Factors; D002480:Cellulase; D005947:Glucose; D007785:Lactose; D005690:Galactose