Functional cloning of an endo-arabinanase from Aspergillus aculeatus and its heterologous expression in A-oryzae and tobacco

Functional cloning in yeast has been used to isolate full-length cDNAs enco ding an endo-alpha -1,5-L-arabinanase from the filamentous fungus Aspergill us aculeatus. Screening of a cDNA library constructed in a yeast expression vector for transformants that hydrolysed AZCL-arabinan identified 44 Sacch aromyces cerevisiae clones all harbouring the same arabinanase-encoding cDN A. The cloned cDNA was expressed in A. oryzae and the recombinant enzyme wa s purified and characterized. The mode of action of the enzyme was studied by analysis of the digestion pattern towards debranched arabinan. The diges tion profile obtained strongly suggests that the enzyme is an endo-arabinan ase. In addition, the feasibility using Nicotiana tabacum as an alternative host for arabinanase expression was investigated.