title: Genome-scale analyses of Escherichia coli and Salmonella enterica AraC reveal noncanonical targets and an expanded core regulon.
abstract: Escherichia coli AraC is a well-described transcription activator of genes involved in arabinose metabolism. Using complementary genomic approaches, chromatin immunoprecipitation (ChIP)-chip, and transcription profiling, we identify direct regulatory targets of AraC, including five novel target genes: ytfQ, ydeN, ydeM, ygeA, and polB. Strikingly, only ytfQ has an established connection to arabinose metabolism, suggesting that AraC has a broader function than previously described. We demonstrate arabinose-dependent repression of ydeNM by AraC, in contrast to the well-described arabinose-dependent activation of other target genes. We also demonstrate unexpected read-through of transcription at the Rho-independent terminators downstream of araD and araE, leading to significant increases in the expression of polB and ygeA, respectively. AraC is highly conserved in the related species Salmonella enterica. We use ChIP sequencing (ChIP-seq) and RNA sequencing (RNA-seq) to map the AraC regulon in S. enterica. A comparison of the E. coli and S. enterica AraC regulons, coupled with a bioinformatic analysis of other related species, reveals a conserved regulatory network across the family Enterobacteriaceae comprised of 10 genes associated with arabinose transport and metabolism.
authors.affiliation: Wadsworth Center, New York State Department of Health, Albany, New York, USA.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Stringer
authors.forename: Salvatore
authors.initials: S
authors.lastname: Currenti
authors.forename: Richard P
authors.initials: RP
authors.lastname: Bonocora
authors.forename: Catherine
authors.initials: C
authors.lastname: Baranowski
authors.forename: Brianna L
authors.initials: BL
authors.lastname: Petrone
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Palumbo
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Reilly
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
authors.forename: Ivan
authors.initials: I
authors.lastname: Erill
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Wade
mesh_terms: D051777:AraC Transcription Factor / Q000235:genetics / Q000378:metabolism*; D001089:Arabinose; D001483:Base Sequence; D001665:Binding Sites; D002874:Chromosome Mapping; D004269:DNA, Bacterial; D012321:DNA-Directed RNA Polymerases; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D016680:Genome, Bacterial; D018085:Regulon; D019779:Salmonella enterica / Q000235:genetics / Q000378:metabolism*
chemical_list: D051777:AraC Transcription Factor; C497371:AraC protein, E coli; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D001089:Arabinose; D012321:DNA-Directed RNA Polymerases