Xyr1 (Xylanase Regulator 1) Regulates both the Hydrolytic Enzyme System and d -Xylose Metabolism in Hypocrea jecorina

Abstract

Hypocrea jecorina (anamorph Trichoderma reesei) is a fungus of noteworthy industrial importance, mainly because of its employment in both fermentative production of native extracellular enzymes and heterologous protein production. Hydrolases secreted by this fungus have achieved broad areas of applications, e.g., in pulp and paper (4, 35, 50), food and feed (9, 27, 49), and textile (23,26,36) industries. The set of hydrolytic enzymes produced by H. jecorina comprises two main cellobiohydrolases, CBHI and CBHII (EC 3.2.1.91) (43); endo-␤-1,4-glucanases EGI to EGV (EC 3.2

Two Major Facilitator Superfamily Sugar Transporters from Trichoderma reesei and Their Roles in Induction of Cellulase Biosynthesis

“…Another 59 genes dominated by 11 cellulase genes, 6 hemicellulase genes, and 6 genes encoding putative transporters (Stp1-moderately down-regulated group) were moderately up-regulated by the absence of Stp1. The up-regulation of the above genes including xyr1, which has been shown to play a major role in the regulation of cellulases in T. reesei (27), may contribute to the observed enhanced cellulolytic response in the ⌬stp1 mutant on Avicel. Of specific interest, the two transporters (Tr_80058 and Tr_3405) up-regulated in the absence of Stp1 were annotated as MFS sugar transporters, and the upregulation of Tr_3405 within the WT Avicel regulon was confirmed by Northern blot and quantitative RT-PCR (Fig.…”

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

“…Parallel DNA-and RNA-extraction and reverse transcription was performed as described previously [22]. PCRs were performed in an iCycler iQ, Real-Time Detection System (Biorad, Herkules, US).…”

“…PCRs were performed in an iCycler iQ, Real-Time Detection System (Biorad, Herkules, US). Taqman assays for monitoring xyn1, xyn2, cbh1, and cbh2 transcript levels were carried out as published elsewhere [22]. For xyr1, xyl1, gal1 and bga1 transcription analysis, a SYBR Green assay with reference to actin was performed including 1· iQ SYBR Green Supermix (Biorad), 0.1 lM forward primer, 0.1 lM reverse primer, and cDNA as template.…”

“…xylan, cellulose, xylobiose, xylose or sophorose [22]. To investigate if the lactose signal is also mediated by Xyr1, the H. jecorina QM9414 strain and a Dxyr1-strain were cultivated on lactose-containing medium.…”

“…Furthermore, it has been reported that Xyr1 is indispensable for transcriptional regulation of the major hydrolytic enzyme-encoding genes, e.g. cbh1 and cbh2 (cellobiohydrolases I and II, EC 3.2.1.-and EC 3.2.1.91, respectively), egl1 (endo-b-1,4-glucanase I, EC 3.2.1.4), xyn1 and xyn2 (endo-b-1,4-xylanase I and II, EC 3.2.1.8), bxl1 (b-xylosidase I, EC 3.2.1.37) as well as bgl1 (1,4-b-glucosidase I, EC 3.2.1.21) [22]. Xyr1 mediates the induction of gene expression of the above mentioned genes regardless of the mode of gene expression (basal, derepressed or induced) or of the applied inducer (xylose, xylobiose, or sophorose) [22].…”