title: Functional genomics: expression analysis of Escherichia coli growing on minimal and rich media.
abstract: DNA arrays of the entire set of Escherichia coli genes were used to measure the genomic expression patterns of cells growing in late logarithmic phase on minimal glucose medium and on Luria broth containing glucose. Ratios of the transcript levels for all 4,290 E. coli protein-encoding genes (cds) were obtained, and analysis of the expression ratio data indicated that the physiological state of the cells under the two growth conditions could be ascertained. The cells in the rich medium grew faster, and expression of the majority of the translation apparatus genes was significantly elevated under this growth condition, consistent with known patterns of growth rate-dependent regulation and increased rate of protein synthesis in rapidly growing cells. The cells grown on minimal medium showed significantly elevated expression of many genes involved in biosynthesis of building blocks, most notably the amino acid biosynthetic pathways. Nearly half of the known RpoS-dependent genes were expressed at significantly higher levels in minimal medium than in rich medium, and rpoS expression was similarly elevated. The role of RpoS regulation in these logarithmic phase cells was suggested by the functions of the RpoS dependent genes that were induced. The hallmark features of E. coli cells growing on glucose minimal medium appeared to be the formation and excretion of acetate, metabolism of the acetate, and protection of the cells from acid stress. A hypothesis invoking RpoS and UspA (universal stress protein, also significantly elevated in minimal glucose medium) as playing a role in coordinating these various aspects and consequences of glucose and acetate metabolism was generated. This experiment demonstrates that genomic expression assays can be applied in a meaningful way to the study of whole-bacterial-cell physiology for the generation of hypotheses and as a guide for more detailed studies of particular genes of interest.
authors.affiliation: Department of Microbiology, The Ohio State University, Columbus, Ohio 43210-1292, USA.
authors.forename: H
authors.initials: H
authors.lastname: Tao
authors.forename: C
authors.initials: C
authors.lastname: Bausch
authors.forename: C
authors.initials: C
authors.lastname: Richmond
authors.forename: F R
authors.initials: FR
authors.lastname: Blattner
authors.forename: T
authors.initials: T
authors.lastname: Conway
mesh_terms: D000596:Amino Acids / Q000096:biosynthesis; D000604:Amino Acyl-tRNA Synthetases / Q000096:biosynthesis; D018407:Bacterial Physiological Phenomena; D001426:Bacterial Proteins; D003470:Culture Media; D004734:Energy Metabolism; D004926:Escherichia coli / Q000235:genetics*; D005227:Fatty Acids / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D005942:Gluconates; D005947:Glucose; D009711:Nucleotides / Q000096:biosynthesis; D020411:Oligonucleotide Array Sequence Analysis; D014176:Protein Biosynthesis; D012269:Ribosomal Proteins / Q000096:biosynthesis; D012808:Sigma Factor; D014815:Vitamins / Q000096:biosynthesis
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D003470:Culture Media; D005227:Fatty Acids; D005942:Gluconates; D009711:Nucleotides; D012269:Ribosomal Proteins; D012808:Sigma Factor; D014815:Vitamins; C069567:sigma factor KatF protein, Bacteria; D000604:Amino Acyl-tRNA Synthetases; D005947:Glucose; C030691:gluconic acid