title: Green fluorescent protein is superior to blue fluorescent protein as a quantitative reporter of promoter activity in E. coli.
abstract: Fluorescent proteins related to and derived from green fluorescent protein (GFP) are widely used as tools for investigating a wide range of biological processes. In particular, GFP and its relatives have been used extensively as qualitative reporters of gene expression in many different organisms, but relatively few studies have investigated fluorescent proteins as quantitative reporters of gene expression. GFP has some limitations as a reporter gene, including possible toxicity when expressed at high levels. Therefore, it would be useful if other fluorescent proteins could be identified for use as quantitative reporters. Toward this end, we investigated BFP as a quantitative reporter of promoter activity in E. coli and directly compared it with GFPuv using a set of well-characterized synthetic constitutive promoters. The fluorescence produced in E. coli strains expressing GFPuv or BFP grown on solid medium was quantified using a CCD camera and fluorimetry. GFPuv consistently gave more reliable and statistically significant results than did BFP in all assays. Correspondingly, we found that the signal-to-noise ratio for GFPuv fluorescence is substantially higher than for BFP. We conclude that, under the conditions assessed in this study, GFPuv is superior to BFP as a quantitative reporter of promoter activity in E. coli.
authors.affiliation: Department of Biology, John Carroll University, University Heights, OH 44118, USA. jlissemore@jcu.edu
authors.forename: James L
authors.initials: JL
authors.lastname: Lissemore
authors.forename: Joshua
authors.initials: J
authors.lastname: Bayes
authors.forename: Molly
authors.initials: M
authors.lastname: Calvey
authors.forename: Lucas
authors.initials: L
authors.lastname: Reineke
authors.forename: Anne
authors.initials: A
authors.lastname: Colagiavanni
authors.forename: Melissa
authors.initials: M
authors.lastname: Tscheiner
authors.forename: David P
authors.initials: DP
authors.lastname: Mascotti
mesh_terms: D001681:Biological Assay; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D008164:Luminescent Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic
chemical_list: D008164:Luminescent Proteins; C409504:blue fluorescent protein, Aequorea victoria; D049452:Green Fluorescent Proteins