Functional characterization and evolutionary implication of the internal 157-amino-acid sequence of an exoinulinase from Penicillium sp. strain TN-88.

摘要: An extracellular exoinulinase from the filamentous fungus Penicillium sp. strain TN-88 has a 14-fold higher specific activity of 743 U/mg toward inulin than its equivalent Aspergillus niger 12 and possesses an internal 157-amino-acid sequence whose corresponding region is absent in A. enzyme. On basis alignment, D′ encoding gene inuD cDNA was inserted into site between nucleotides 897 898 inuE cDNA. The resultant inuE::D′ fusion expressed methylotrophic yeast Pichia pastoris. Km value secreted hybrid enzyme InuE::D′ for hydrolysis about 1/15 that InuE, whereas kcat did not differ greatly InuE. These observations indicate evolved by horizontal transfer integration relevant DNA segment functions as additional noncatalytic inulin-affinity region.