Cloning and Sequence Analysis of the Cellobiohydrolase I Genes from Some Basidiomycetes

Genes encoding the cellobiohydrolase enzyme (CBHI), designated as cbhI, were isolated from the basidiomycetes Auricularia fuscosuccinea, Pleurotus giganteus, P. eryngii, P. ostreatus, and P. sajor-caju. Initially, the fungal genomic DNA was extracted using a modified cetyltrimethyl ammonium bromide (CTAB) protocol and used as a DNA template. The cbhI genes were then amplified and cloned using the pGEM-T Easy Vector Systems. The sizes of these PCR amplicons were between 700~800 bp. The DNA sequences obtained were similar showing high identity to the cbhI gene family. These cbhI genes were partial consisting of three coding regions and two introns. The deduced amino acid sequences exhibited significant similarity to those of fungal CBHI enzymes belonging to glycosyl hydrolase family 7.

A Secretive Pichia pastoris Expression Vector for Direct PCR Product Cloning / 中国生物工程杂志

A secretive expression vector of Pichia pastoris system which can be used for the direct cloning of PCR products was constructed,and was verified through the expression of recombinant cellobiohydrolase II in Pichia pastoris.A randomly selected fragment was amplified with properly designed primers by PCR.The XhoI and Eam1105Ⅰ restriction sites were included in the 5'end of the fragment,and the Eam1105Ⅰ and XbaI restriction sites were included in its 3'end.The PCR amplified product was inserted into the P.pastoris expression plasmid pPICZ?A through XhoI and XbaI restriction sites and the resultant plasmid was digested with Eam1105Ⅰ,and lastly the big fragment was recovered,generating the P.pastoris expressive Tvector pPICZ?T.Then the cellobiohydrolase II of T.reesei was successfully expressed in P.pastoris with this expressive Tvector.Such results indicated that the constructed expression Tvector was convenient for PCR product cloning,and was effective for heterologous protein expression in P.pastoris.On the other hand,the application of the expression Tvector avoided the introduction of additional amino acids at the Nterminus of the expressed protein,which generally occurred when normal expression vectors were used in secretive expression system.