title: Development and functional analysis of novel genetic promoters using DNA shuffling, hybridization and a combination thereof.
abstract: BACKGROUND
  Development of novel synthetic promoters with enhanced regulatory activity is of great value for a diverse range of plant biotechnology applications.
  
  
  METHODS
  Using the Figwort mosaic virus full-length transcript promoter (F) and the sub-genomic transcript promoter (FS) sequences, we generated two single shuffled promoter libraries (LssF and LssFS), two multiple shuffled promoter libraries (LmsFS-F and LmsF-FS), two hybrid promoters (FuasFScp and FSuasFcp) and two hybrid-shuffled promoter libraries (LhsFuasFScp and LhsFSuasFcp). Transient expression activities of approximately 50 shuffled promoter clones from each of these libraries were assayed in tobacco (Nicotiana tabacum cv. Xanthi) protoplasts. It was observed that most of the shuffled promoters showed reduced activity compared to the two parent promoters (F and FS) and the CaMV35S promoter. In silico studies (computer simulated analyses) revealed that the reduced promoter activities of the shuffled promoters could be due to their higher helical stability. On the contrary, the hybrid promoters FuasFScp and FSuasFcp showed enhanced activities compared to F, FS and CaMV 35S in both transient and transgenic Nicotiana tabacum and Arabidopsis plants. Northern-blot and qRT-PCR data revealed a positive correlation between transcription and enzymatic activity in transgenic tobacco plants expressing hybrid promoters. Histochemical/X-gluc staining of whole transgenic seedlings/tissue-sections and fluorescence images of ImaGene Green™ treated roots and stems expressing the GUS reporter gene under the control of the FuasFScp and FSuasFcp promoters also support the above findings. Furthermore, protein extracts made from protoplasts expressing the human defensin (HNP-1) gene driven by hybrid promoters showed enhanced antibacterial activity compared to the CaMV35S promoter.
  
  
  CONCLUSIONS
  Both shuffled and hybrid promoters developed in the present study can be used as molecular tools to study the regulation of ectopic gene expression in plants.
authors.affiliation: Department of Gene Function and Regulation, Institute of Life Sciences, Department of Biotechnology, Government of India, Chandrasekherpur, Bhubaneswar, Odisha, India.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Ranjan
authors.forename: Sunita
authors.initials: S
authors.lastname: Patro
authors.forename: Bhubaneswar
authors.initials: B
authors.lastname: Pradhan
authors.forename: Alok
authors.initials: A
authors.lastname: Kumar
authors.forename: Indu B
authors.initials: IB
authors.lastname: Maiti
authors.forename: Nrisingha
authors.initials: N
authors.lastname: Dey
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D001483:Base Sequence; D015152:Blotting, Northern; D032621:DNA Shuffling / Q000379:methods*; D018506:Gene Expression Regulation, Plant; D015967:Gene Expression Regulation, Viral; D015723:Gene Library; D005820:Genetic Testing; D016679:Genome, Viral / Q000235:genetics; D005966:Glucuronidase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009029:Mosaic Viruses / Q000235:genetics; D009154:Mutation / Q000235:genetics; D009693:Nucleic Acid Hybridization / Q000379:methods*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D011523:Protoplasts / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014026:Nicotiana / Q000235:genetics
chemical_list: D049452:Green Fluorescent Proteins; D005966:Glucuronidase