title: Chromosome position effects on gene expression in Escherichia coli K-12.
abstract: In eukaryotes, the location of a gene on the chromosome is known to affect its expression, but such position effects are poorly understood in bacteria. Here, using Escherichia coli K-12, we demonstrate that expression of a reporter gene cassette, comprised of the model E. coli lac promoter driving expression of gfp, varies by ∼300-fold depending on its precise position on the chromosome. At some positions, expression was more than 3-fold higher than at the natural lac promoter locus, whereas at several other locations, the reporter cassette was completely silenced: effectively overriding local lac promoter control. These effects were not due to differences in gene copy number, caused by partially replicated genomes. Rather, the differences in gene expression occur predominantly at the level of transcription and are mediated by several different features that are involved in chromosome organization. Taken together, our findings identify a tier of gene regulation above local promoter control and highlight the importance of chromosome position effects on gene expression profiles in bacteria.
authors.affiliation: Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Jack A
authors.initials: JA
authors.lastname: Bryant
authors.affiliation: Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Sellars
authors.affiliation: Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Stephen J W
authors.initials: SJ
authors.lastname: Busby
authors.affiliation: Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK D.lee@bham.ac.uk.
authors.forename: David J
authors.initials: DJ
authors.lastname: Lee
mesh_terms: D045584:Chromosome Positioning; D027081:DNA Gyrase / Q000378:metabolism; D048168:Escherichia coli K12 / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
chemical_list: D027081:DNA Gyrase