title: Different inducibility of expression of the two xylanase genes xyn1 and xyn2 in Trichoderma reesei.
abstract: Regulation of formation of the extracellular xylanase system of Trichoderma reesei QM 9414 during growth on xylan, cellulose, and replacement onto a number of soluble inducers was investigated by Northern analysis of xyn1 and xyn2 transcripts and by the use of the Escherichia coli hph (hygromycin B-phosphotransferase-encoding) gene as a reporter. Whereas the xyn1 promoter is active in the presence of xylan and xylose, and virtually silenced in the presence of glucose, the xyn2 promoter enables basal transcription at a low level, but is enhanced in the presence of xylan and xylobiose and also of sophorose or cellobiose. The respective regulatory nucleotide regions were localized on a 221-base pair fragment and a 55-base pair fragment of the xyn1 and xyn2 5'-upstream noncoding sequences, respectively. Electrophoretic mobility shift assays, using cell-free extracts, identified induction-specific protein-DNA complexes: one complex of high mobility was observed under basal, noninduced conditions (glucose) with xyn2, which was in part replaced by a slow-migrating complex upon induction by xylan or sophorose. Both complexes bound to a CCAAT box. With xyn1, the induced complex also binds to a CCAAT box, but this binding is not observed in the presence of the carbon catabolite repressor Cre1, which binds to a nearby located consensus motif.
authors.affiliation: Abteilung für Mikrobielle Biochemie, Institut für Biochemische Technologie und Mikrobiologie, TU Wien, A-1060 Wien, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Zeilinger
authors.forename: R L
authors.initials: RL
authors.lastname: Mach
authors.forename: M
authors.initials: M
authors.lastname: Schindler
authors.forename: P
authors.initials: P
authors.lastname: Herzog
authors.forename: C P
authors.initials: CP
authors.lastname: Kubicek
mesh_terms: D001483:Base Sequence; D002241:Carbohydrates / Q000494:pharmacology; D017931:DNA Primers; D004790:Enzyme Induction / Q000187:drug effects; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis; D014158:Transcription, Genetic; D014242:Trichoderma / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D043325:Xylan Endo-1,3-beta-Xylosidase; D014995:Xylosidases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D002241:Carbohydrates; D017931:DNA Primers; D011994:Recombinant Proteins; D014995:Xylosidases; D043325:Xylan Endo-1,3-beta-Xylosidase