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Influenza A/H1N1 virus-encoded nonstructural, or NS1, protein inhibits the 3'-end processing of cellular pre-mRNAs by binding the cellular protein: the 30-kDa subunit of CPSF (cleavage and polyadenylation specificity factor, CPSF30). CPSF30 binding site of the NS1 protein is a potential target for the development of drugs against influenza A/H1N1 virus. A yeast two-hybrid screening system was constructed and used for screening Chinese medicines that inhibit the interaction of the A/H1N1 flu NS1 protein and human CPSF30 protein. The NS1 gene of A/H1N1 virus was amplified by consecutive polymerase chain reaction (PCR), and the human CPSF30 gene of HeLa cell cloned by reverse transcriptase-polymerase chain reaction (RT-PCR). Then the two gene fragments confirmed by sequencing were subcloned into the yeast expression vectors pGBKT7 and pGADT7, respectively. The two constructs, bait vector pGBKNS1 and prey vector pGADCPSF, were co-transformed into yeast AH109. The eight individual yeast colonies were picked and subjected to verification by PCR/gel electrophoresis. The inhibition of the NS1-CPSF30 interaction was allowed the identification of selective inhibitors. The four of more than thirty identified Chinese medicines, including 'Shuanghuanglian oral liquid', showed the strong inhibition of the NS1-CPSF30 interaction.

Amorpha-4,11-diene synthase (ADS) can convert farnesyl pyrophosphate (FPP) to amorpha-4, 11-diene, a precursor of artemisinin. ADS plays an important role in the biosynthesis of artemisinin. This review summarizes the molecular biology and metabolic engineering study of ADS in recent years. The genomic DNA and its cDNA sequences of amorpha-4, 11-diene synthase were cloned from Artemisia annua L. The cDNA encoding amorpha-4, 11-diene synthase contains a 1 641 bp open reading frame coding for 546 amino acids. ADS shows a broad pH optimum and an absolute requirement for divalent metal ions as cofactors. The specificity of ADS to the substrates and products is not high and the formation of amorpha-4, 11-diene by ADS from FPP is achieved by an initial 1, 6-closure with subsequent 1, 10-closure. The ADS cDNA cloned from Artemisia annua L, or totally synthesized by PCR, was introduced into different hosts including E. coli, S. cerevisiae, Nicotiana tabacum L. Arabidopsis thaliana and A. nidulans resulting in varied engineering microorganisms and cells producing amorpha-4, 11-diene. The way to improve the production of amorpha-4, 11-diene was investigated by two strategies such as improving the supply of substrate and directing FPP flux to amorpha-4, 11-diene production from competing pathways.

Plasmid-carrying Saccharomyces cerevisia (W303-1B[pYeDP60/G/ADS]) and genome-transformed S. cerevisia (W303-1B[rDNA:ADS]), both harboring amorpha-4,11-diene synthase (ADS) gene were constructed to investigate the production of amorpha-4,11-diene. The recombinant plasmid pYeDP60/G/ADS that harbors the ADS gene was transformed into S. cerevisiae W303-1B, resulting in the engineered yeast W303-1B[pYeDP60/G/ADS], which contains multi-copies of the plasmid. The ADS gene expression cassette was obtained by PCR amplification of the pYeDP60/G/ADS template, and then introduced into S. cerevisiae W303-1B to obtain the engineered yeast W303-1B[rDNA:ADS], in which the ADS gene was integrated into the rDNA locus of the yeast genome through the homologous recombination. GC-MS analysis confirmed that both of the engineered yeasts could produce amorpha-4,11-diene. Moreover, the amorpha-4,11-diene yield of W303-1B[pYeDP60/G/ADS] was higher than that of W303-1B[rDNA:ADS]. Southern blot analysis showed that there is only one copy of ADS gene in the genome of W303-1B[rDNA:ADS]. It implied that the amorpha-4,11-diene yield can be improved by increasing the ADS gene copies.