Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9603090 | Journal of Bioscience and Bioengineering | 2005 | 8 Pages |
Abstract
An extracellular endo-1,4-β-xylanase was purified from the culture filtrate of a filamentous fungus Penicillium citrinum FERM P-15944 grown on birch-wood xylan. The purified enzyme showed a single band on SDS-PAGE with an apparent Mr of 20,000 and had an isoelectric point below 3.5. Xylanase activity was optimal at pH 5.0 and 55°C. The genomic DNA and cDNAs encoding this protein were cloned and sequenced. Southern blot analysis indicated that the xylanase gene (xynA) was present as a single copy in the genome. An open reading frame of 657 bp was interrupted by two introns of 65 and 55 bp, and encoded a presumed prepropeptide of 27 amino acids and a mature protein of 190 amino acids. Three distinct transcription start points were observed at positions â20 (A), â31 (A), and â36 (A) from the start codon. The 5â²-noncoding region had a putative TATA box at nt â66 (TATAAA). The xynA cDNA was functionally expressed under the control of the alcohol oxidase I gene promoter in the methylotrophic yeast Pichia pastoris. A neighbor-joining tree showed that the P. citrinum enzyme is closely related to several other fungal xylanases belonging to the glycoside hydrolase family 11: Trichoderma reesei XYN2, Aspergillus niger xynNB, Penicillium funiculosum xynC, Penicillium sp. strain 40 xynA, Chaetomium gracile cgxB, and Aspergillus nidulans xlnA and xlnB.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Bioengineering
Authors
Hidenori Tanaka, Toshihide Nakamura, Sachio Hayashi, Kazuyoshi Ohta,