CLONING, CHARACTERIZATION AND FUNCTIONAL EXPRESSION OF AN ENDOGLUCANASE-ENCODING GENE FROM THE PHYTOPATHOGENIC FUNGUS MACROPHOMINA-PHASEOLINA

An endoglucanase-encoding clone (egl2) was isolated from the phytopathogenic soilborne deuteromycete fungus Macrophomina phaseolina (Mp). Clones were obtained from a cDNA library by functional expression in Escherichica coli. The egl2 clone hybridized to a 1.3-kb mRNA. Expression is induced by carboxymethylcellulose (CMC) and repressed by glucose. The deduced amino acid (aa) sequence revealed strong similarity to the egl3 from Trichoderma reesei (Tr) (72% for identical residues and 81% with conservative substitution over a span of 324 aa). The Mp egl2 lacks the cellulose-binding domain and linker region found in the Tr egl3. Different codon usage between the two fungi resulted in a much shorter span of nucleotide homology. The Egl2 protein cleaves cellodextrins with contiguous beta,1-4 linkages of four and larger, and shows activity against CMC and birchwood xylan.