Monday, May 4, 2009
5-28
A cellulase related dehydrogenase of Hypocrea jecorina (Trichoderma reesei) specifically responsive to soluble inducing compounds
André Schuster, Christian P. Kubicek, and Monika Schmoll. Institute of Chemical Engineering, Research Area Molecular Biotechnology, Vienna University of Technology, Getreidemarkt 9/1665, Vienna, Austria
Hypocrea jecorina is nowadays the most important industrial producer of cellulase and hemicellulase enzymes, which are used for pretreatment of cellulosic biomass for biofuel production. This fungus expresses high levels of cellulases on cellulose, lactose and upon induction by sophorose. However, the mechanisms regulating cellulase gene expression on these carbon sources are different. In a study aimed at elucidation of the distinct signaling pathways, we identified a putative short chain dehydrogenase to be expressed upon induction by sophorose and on lactose, but not during growth on cellulose. ccd1 (cellulase correlated dehydrogenase 1) thereby specifically responds to inducing conditions with a larger transcript, while on non inducing carbon sources such as glucose or glycerol only a small transcript was observed. This smaller transcript is also present in mutants, which do not express cellulases under conditions leading to cellulase transcription in the wild-type. We therefore conclude that expression of CCD1 is inducer-dependent or may alternatively be involved in inducer formation. Analysis of growth patterns of a ccd1 deletion strain on 96 carbon souces (BIOLOG) reveals several changes in carbon source utilization.