Regulation of transcription of cellulases- and hemicellulases-encoding genes in Aspergillus niger and Hypocrea jecorina (Trichoderma reesei).

The filamentous fungi Aspergillus niger and Hypocrea jecorina (Trichoderma reesei) have been the subject of many studies investigating the mechanism of transcriptional regulation of hemicellulase- and cellulase-encoding genes. The transcriptional regulator XlnR that was initially identified in A. niger as the transcriptional regulator of xylanase-encoding genes controls the transcription of about 20-30 genes encoding hemicellulases and cellulases.

Role of Ace2 (Activator of Cellulases 2) within the xyn2 transcriptosome of Hypocrea jecorina.

Ace2 (Activator of Cellulases 2)-encoding gene was deleted from and retransformed in the H. jecorinaQM9414 genome. Comparison of xylanase activity and xyn2 transcription of the corresponding strains after cultivation on inducing compounds (xylan, xylobiose) revealed a faster initial inducibility in the Deltaace2-strain, but final levels of xyn2 transcript and xylanase activity of the parental strain could not be reached.

Xyr1 receives the lactose induction signal and regulates lactose metabolism in Hypocrea jecorina.

This study reports the vital regulatory influence of Xyr1 (xylanase regulator 1) on the transcription of hydrolytic enzyme-encoding genes and hydrolase formation on lactose in Hypocrea jecorina. While the transcription of the xyr1 gene itself is achieved by release of carbon catabolite repression, the transcript formation of xyn1 (xylanase 1) is regulated by an additional induction mechanism mediated by lactose. Xyr1 has an important impact on lactose metabolism by directly activating xyl1 (xylose reductase 1) transcription and indirectly influencing transcription of bga1 (beta-galactosidase 1).

Xyr1 (xylanase regulator 1) regulates both the hydrolytic enzyme system and D-xylose metabolism in Hypocrea jecorina.

Xyr1 (xylanase regulator 1) of the ascomycete Hypocrea jecorina (anamorph Trichoderma reesei) was recently demonstrated to play an essential role in the transcriptional regulation of the xyn1 (xylanase 1-encoding) gene expression. Consequently, this study reports on the deletion of the xyr1 gene from the H. jecorina genome.

Transcriptional regulation of xyn1, encoding xylanase I, in Hypocrea jecorina.

Two major xylanases (XYN I and XYN II) of the filamentous fungus Hypocrea jecorina (Trichoderma reesei) are simultaneously expressed during growth on xylan but respond differently to low-molecular-weight inducers. In vivo footprinting analysis of the xylanase1 (xyn1) promoter revealed three different nucleotide sequences (5'-GGCTAAATGCGACATCTTAGCC-3' [an inverted repeat of GGCTAA spaced by 10 bp], 5'-CCAAT-3', and 5'-GGGGTCTAGACCCC-3' [equivalent to a double Cre1 site]) used to bind proteins. Binding to the Cre1 site is only observed under repressed conditions, whereas binding to the two other motifs is constitutive.