title: Unravelling the molecular basis for light modulated cellulase gene expression - the role of photoreceptors in Neurospora crassa.
abstract: BACKGROUND
  Light represents an important environmental cue, which exerts considerable influence on the metabolism of fungi. Studies with the biotechnological fungal workhorse Trichoderma reesei (Hypocrea jecorina) have revealed an interconnection between transcriptional regulation of cellulolytic enzymes and the light response. Neurospora crassa has been used as a model organism to study light and circadian rhythm biology. We therefore investigated whether light also regulates transcriptional regulation of cellulolytic enzymes in N. crassa.
  
  
  RESULTS
  We show that the N. crassa photoreceptor genes wc-1, wc-2 and vvd are involved in regulation of cellulase gene expression, indicating that this phenomenon is conserved among filamentous fungi. The negative effect of VVD on production of cellulolytic enzymes is thereby accomplished by its role in photoadaptation and hence its function in White collar complex (WCC) formation. In contrast, the induction of vvd expression by the WCC does not seem to be crucial in this process. Additionally, we found that WC-1 and WC-2 not only act as a complex, but also have individual functions upon growth on cellulose.
  
  
  CONCLUSIONS
  Genome wide transcriptome analysis of photoreceptor mutants and evaluation of results by analysis of mutant strains identified several candidate genes likely to play a role in light modulated cellulase gene expression. Genes with functions in amino acid metabolism, glycogen metabolism, energy supply and protein folding are enriched among genes with decreased expression levels in the wc-1 and wc-2 mutants. The ability to properly respond to amino acid starvation, i. e. up-regulation of the cross pathway control protein cpc-1, was found to be beneficial for cellulase gene expression. Our results further suggest a contribution of oxidative depolymerization of cellulose to plant cell wall degradation in N. crassa.
authors.affiliation: Plant and Microbial Biology Department, University of California, Berkeley, 94720, USA. monika.schmoll@tuwien.ac.at
authors.forename: Monika
authors.initials: M
authors.lastname: Schmoll
authors.forename: Chaoguang
authors.initials: C
authors.lastname: Tian
authors.forename: Jianping
authors.initials: J
authors.lastname: Sun
authors.forename: Doris
authors.initials: D
authors.lastname: Tisch
authors.forename: N Louise
authors.initials: NL
authors.lastname: Glass
mesh_terms: D002480:Cellulase / Q000235:genetics*; D016000:Cluster Analysis; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal / Q000528:radiation effects*; D005800:Genes, Fungal / Q000235:genetics; D008027:Light; D009492:Neurospora crassa / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects; D020283:Photoreceptors, Microbial / Q000235:genetics / Q000378:metabolism*; D059467:Transcriptome / Q000528:radiation effects
chemical_list: D005656:Fungal Proteins; D020283:Photoreceptors, Microbial; D002480:Cellulase