Codon optimization of xylanase gene xynB from the thermophilic bacterium Dictyoglomus thermophilum for expression in the filamentous fungus Trichoderma reesei

The catalytic domain of the xynB (xylanase) gene from the thermophilic bact erium Dictyoglomus thermophilum was reconstructed by PCR to match the codon preference of Trichoderma reesei. The 0.6-kb DNA fragment encoding the enz yme was first amplified by primer extension with a mixture of eight overlap ping oligonucleotides, followed by PCR with outside primers containing rest riction enzyme sites for directional cloning into Escherichia coli and T. r eesei vectors. The synthetic gene was expressed in both organisms, producin g a clearing halo around transformant colonies in plate assay utilizing an overlay of oat spelts xylan. Effective transcription of xynB in T. reesei w as obtained after changing 20 codons. (C) 2000 Federation of European Micro biological Societies. Published by Elsevier Science B.V. All rights reserve d.