title: Functional analysis of the degradation of cellulosic substrates by a Chaetomium globosum endophytic isolate.
abstract: Most photosynthetically fixed carbon is contained in cell wall polymers present in plant biomasses, the largest organic carbon source in the biosphere. The degradation of these polymers for biotechnological purposes requires the combined action of several enzymes. To identify new activities, we examined which enzymes are activated by an endophytic strain of Chaetomium globosum to degrade cellulose-containing substrates. After biochemical analyses of the secretome of the fungus grown on cellulose or woody substrates, we took advantage of the available genomic data to identify potentially involved genes. After in silico identification of putative genes encoding either proteins able to bind to cellulose or glycohydrolases (GHs) of family 7, we investigated their transcript levels by reverse transcription-quantitative PCR (RT-qPCR). Our data suggest that eight genes compose the core of the cellulose-degrading system of C. globosum. Notably, the related enzymes belong structurally to the well-described GH families 5, 6, 7, 16, and 45, which are known to be the core of the cellulose degradation systems of several ascomycetes. The high expression levels of cellobiose dehydrogenase and two GH 61 enzymes suggest the involvement of this oxidoreductive synergic system in C. globosum. Transcript analysis along with relevant coding sequence (CDS) isolation and expression of recombinant proteins proved to be a key strategy for the determination of the features of two endoglucanases used by C. globosum for the first attack of crystalline cellulose. Finally, the possible involvement of transcriptional regulators described for other ascomycetes is discussed.
authors.affiliation: Department of Biology and Biotechnology, University of Pavia, Pavia, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Longoni
authors.forename: Marinella
authors.initials: M
authors.lastname: Rodolfi
authors.forename: Laura
authors.initials: L
authors.lastname: Pantaleoni
authors.forename: Enrico
authors.initials: E
authors.lastname: Doria
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Concia
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Picco
authors.forename: Rino
authors.initials: R
authors.lastname: Cella
mesh_terms: D002482:Cellulose / Q000378:metabolism*; D002597:Chaetomium / Q000302:isolation & purification* / Q000378:metabolism*; D019295:Computational Biology; D060026:Endophytes / Q000302:isolation & purification* / Q000378:metabolism*; D020869:Gene Expression Profiling; D006868:Hydrolysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014934:Wood / Q000378:metabolism
chemical_list: D002482:Cellulose