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Abstract Mycoparasitic chitinases play an important role in resisting plant diseases for their strong capacity of degrading chitin. In order to clone and study chitinase gene(tfchi1) fromTalaromyces flavus, a pair of degenerate primers were designed according to the conserved sequences of chitinase genes in other fungi. The full-length DNA and cDNA of tfchi1 were cloned by using RT-PCR, 3'-RACE and 5'-TAIL (GenBank: GU361769, GU361770). The full-length DNA of tfchi1 was 2 561 bp, containing six introns with the length of 129, 78, 68, 65, 53 and 59 bp, respectively, ORF was 1 194 bp and it encoded 397 amino acids. Based on the predicted amino acid sequence of tfchi1 and the bioinformatic analysis of protein structure, two prevalent conserved catalytic domains with the sequences of SXGGW and DGXDXDWE were identified, Tfchi1 belonged to family 18 glycoside hydrolase, and shared 96% homology with the sequence of chitinase (XP-002480365) from Talaromyces stipitatus ATCC 10550. Its predicted molecular weight and isoelectric point were 43.47 kD and 4.97, respectively. Tfchi1 had no signal peptide sequence but 15 potential N-glycosylation sites. Random coils and α-helices were the major structural elements in secondary structure of Tfchi1, while(α/β) 8 rounded buckets were evident in tertiary structure. A recombinant protein with chitinase activity was obtained after tfchi1 was transformed into Pichia pastoris GS115 and its molecular weight was also consistent to the theoretical value. The results show that a chitinase gene, belonging to family 18 glycoside hydrolase, is correctly cloned from T. flavus in this study.
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Received: 08 April 2011
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