title: The rrnA promoter as a tool for the improved expression of heterologous genes in cyanobacteria.
abstract: The regulatory sequence of ribosomal RNA A (rrnA) operon from Synechococcus PCC7942 was characterized using green fluorescent protein gene (gfp) as a reporter. The PR promoter (nt. -83 to +2) including upstream promoter element and P1 promoter of rrnA exhibited GFP fluorescence intensity about 30-fold higher than full length sequence (nt. -147 to +79). The effects of PR promoter arranged in tandem with consensus-σ(70) promoter (PS) of Escherichia coli on the expression of gfp and opd gene encoding organophosphorus hydrolase (OPH) in Synechococcus were investigated. The PS-PR tandem promoter was superior to all of the other promoters; its GFP fluorescence intensity was a 1.8-fold increase when compared to PR-PR tandem promoter, a 2.5-fold, 9.5-fold and a 15-fold increase compared to PR, PS and promoter of tRNA(pro), respectively. The GFP from PS-PR tandem promoter accounted for about 12% of its total extracted proteins. OPH activity of Synechococcus harboring opd gene under the control of PS-PR tandem promoter was 738 ± 128 units/OD₇₃₀. We demonstrated that the tandem promoters remarkably enhanced the GFP and OPH production which were detected on SDS-PAGE stained with Coomassie blue. The promoter system in this study could be generally applied to production of valuable organic products from cyanobacteria.
authors.affiliation: Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand. Electronic address: wipa.chu@mahidol.ac.th.
authors.forename: Wipa
authors.initials: W
authors.lastname: Chungjatupornchai
authors.affiliation: Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand.
authors.forename: Sirirat
authors.initials: S
authors.lastname: Fa-Aroonsawat
mesh_terms: D019677:Artificial Gene Fusion; D043303:Aryldialkylphosphatase / Q000096:biosynthesis / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D017930:Genes, Reporter; D005827:Genetics, Microbial / Q000379:methods*; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D008967:Molecular Biology / Q000379:methods*; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000235:genetics; D012808:Sigma Factor / Q000235:genetics; D046940:Synechococcus / Q000235:genetics*
chemical_list: D011994:Recombinant Proteins; D012808:Sigma Factor; D049452:Green Fluorescent Proteins; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases; D043303:Aryldialkylphosphatase
keywords: Green fluorescent protein (GFP); Organophosphorus hydrolase; Tandem promoter; Xyanobacteria; rrnA operon