Cloning and characterization of full-length cDNA of chitinase gene from Isaria farinosa
粉棒束孢几丁质酶基因cDNA全序列克隆及结构特征分析

The full-length cDNA coding the chitinases produced by the biocontrol agent Isaria farinosa using SMART RACE RT-PCR was reported in this paper. Analysis of the cloned complete cDNA, with a whole sequence of 1549bp, showed that it encompassed an open reading frame (ORF) of 1272bp encoding 423 amino acids with a stretch of 22 amino acid residues displaying characteristics of signal peptide. The result showed that the mature chitinase (without signal sequence) had a molecular mass of 43.9 kDa with a calculated pI of 5.67. This sequence contained two highly conserved regions of the active domain of the family 18 glycosyl hydrolases including a presumed enzymatic active site and a potential chitin-binding domain. The cloned Isaria chinitase belongs to the class V in 18 family of glycosyl hydrolase. Alignments with the deduced amino acid of mature proteins in 5 species of fungi showed 91%, 89%, 80%, 76% and 75%, respectively, identical with those of Torrubiella confragosa (AAV98691), Aphanocladium album (CAA45468), Verticillium fungicola (AAP45631), Nomuraea rileyi (AAP04616) and Beauveria bassiana (AAN41261), respectively.