THE USE OF CONSERVED CELLULASE FAMILY-SPECIFIC SEQUENCES TO CLONE CELLULASE HOMOLOG CDNAS FROM FUSARIUM-OXYSPORUM

Five cDNAs from the cellulolytic fungi Fusarium oxysporum that code fo r five distinct cellulase homologues have been cloned and sequenced. T he cloning strategy exploited the hydrophobic cluster analysis-based c ellulase family classification of Henrissat and Bairoch [Biochem. J. 2 93 (1993) 781-788] to design degenerate oligodeoxyribonucleotides (oli gos) that encoded amino-acid sequences conserved in an intra-family, b ut not inter-family, manner among cellulases from different species. P olymerase chain reaction (PCR) experiments using F. oxysporum genomic DNA primed with these 'family-specific' oligos were used to rapidly ge nerate PCR fragments which were in turn used to probe cDNA libraries. Two distinct cDNAs coding for cellulase C-family homologues and one cD NA each coding for homologues to the B, F and K families, were isolate d in this manner. This approach is an example of the power of multiple sequence analysis to generate cross-species, homology-based probes to rapidly clone homologues in a species of interest.