Glucuronoyl esterase facilitates biomass degradation in Neurospora crassa by upregulating the expression of plant biomass-degrading enzymes

[摘要] Glucuronoyl esterase (GE) is a promising agent forthe delignification of plant biomass since it has beenshown to cleave the linkage between xylan and ligninin vitro. In this study, we demonstrate that NcGE,a GE from Neurospora crassa, stimulates plant biomass degradation. In vitro, NcGE synergisticallyincreased the release of reducing sugars from plantbiomass when added together with cellulase orxylanase. In vivo, overexpression of NcGE in N.crassa resulted in an increase in xylanolytic activity.Consistently, elevated transcription of genes encoding the major plant biomass degrading-enzymes(PBDEs) was observed in the NcGE-overexpressionstrain. Increased xylanolytic activity and transcription of PDBE genes were largely abolished when thetranscription factors clr-1, clr-2, or xlr-1 were deleted.Interestingly, the expression of some PBDE geneswas increased when the hydrolysate of plant biomassby NcGE was added to the culture medium. We propose that NcGE boosts the production of PBDEsthrough the activation of key transcription factors,which is presumably caused by NcGE-mediatedgeneration of hypothetical inducer(s) from plantbiomass.

[学科分类] 微生物学和免疫学

[关键词] cellulase;glucuronoyl esterase;Neurospora crassa;plant biomass;xylanase