Abstract: Acidic xylanases have extensive application in feed and wine industries. The whole sequence of the gene xynA encoding acidic xylanase was amplified from Penicillium janthinellum MA21601 by genome walking. A cDNA sequence was obtained through the elimination of introns by overlapping PCR and analyzed by bioinformatics. The whole sequence was about 720 bp in length with only one intron of 63 bp. The cDNA sequence was 657 bp long and putatively encoded a protein which contained a 28-amino acid (aa) signal peptide and a 190-aa mature peptide. The molecular weight of the protein was estimated to be about 20.61 kD, which had an isoelectric point of 7.0. Bioinformatics analysis showed that XynA was a hydrophilic protein without disulfide bond. The amino acid sequence comparison of XynA with other fungal GH11 acidophilic xylanases indicated that the XynA had an identified specific recognition site of Asp, which displayed a β-jelly-roll architecture as a conserved region which was the characteristic of the GH11 family xylanases. The recombinant xylanase was successfully expressed in Escherichia coli with a specific activity of up to 220.5 U/mg.

Key words: Penicillium janthinellum, acidophilic xylanase, gene cloning, bioinformatics analysis