Improved heterologous gene expression in Trichoderma reesei by cellobiohydrolase I gene （cbh1） promoter optimization

To improve heterologous gene expression in Trichoderma reesei, a set of optimal artificial cellobiohydrolase I gene （cbhl） promoters was obtained. The region from -677 to -724 with three potential glucose repressor binding sites was deleted. Then the region from -620 to -820 of the modified cbhl promoter, including the CCAAT box and the Ace2 binding site, was repeatedly inserted into the modified cbhl promoter, obtaining promoters with copy numbers 2, 4, and 6. The results showed that the glucose repression effects were abolished and the expression level of the glucuronidase （gus） reporter gene regulated by these multi-copy promoters was markedly enhanced as the copy number increased simultaneously. The data showed the great promise of using the promoter artificial modification strategy to increase heterologous gene expression in filamentous fungi and provided a set of optional high-expression vectors for gene function investigation and strain modification.     

Deletional analysis of functional regions of complementary sense promoter from cotton leaf curl virus

Complementary sense promoter from cotton leaf curl virus (CLCuV) is a novel plant promoter for genetic engineering that could drive high-level foreign gene expression in plant. To determine the optimal promoter sequence for gene expression, CLCuV promoter was deleted from its 5' end to form promoter fragments with five different lengths, and chimeric gus genes were constructed using the promoterdeletion. These vectors were delivered into Agrobacterium and tobacco (Nicotiana tabacum L cv. Xanthi) plants which were transformed by leaf discs method. GUS activity of transgenic plants was measured. The results showed that GUS activities with the promoter deleted to -287 and -271 from the translation initiation site were respectively about five and three times that of full-length promoter. There exists a c/s-element which is important for the expressing activity in phloem from -271 to -176. Deletion from -176 to -141 resulted in a 20-30-fold reduction in GUS activity in leaves with weak activity in leaves and