Molecular cloning and characterization of cel2 from the fungus Cochlibolus carbonum

A new cellulase gene, cel2, from the filamentous fungus Cochliobolus carbonum was cloned by using egl-1 of Trichoderma reesei as a heterologous probe. DNA blot analysis of cel2 showed that this gene is present as a single copy. The gene contains one 49-bp- intron. cel2 encodes a predicted protein (Cel2p) of 423 amino acids with a molecular mass of 45.8 kDa. The predicted pI is 4.96. It shows similarity to other endoglucanases from various fungi. From the comparison with other cellulase genes, cel2 belongs to family 7 of glucohydrolases. cel2 is located on a 2.5-Mb chromosome in C. carbonum and its expression is repressed by sucrose. A cel2 mutant of C. carbonum was created by transformation-mediated gene disruption. The pathogenicity of the mutant was indistinguishable from the wild type, indicating that cel2 by itself is not important for pathogenicity.