title: New insights into the role of sigma factor RpoS as revealed in escherichia coli strains lacking the phosphoenolpyruvate:carbohydrate phosphotransferase system.
abstract: It has been demonstrated that about 10% of the Escherichia coli genes are under direct or indirect control of RpoS. Therefore, Weber et al. [2005] proposed that this sigma subunit should be considered a second vegetative sigma factor under non-optimal growth conditions. In this report we demonstrate that in the phosphoenolpyruvate:carbohydrate phosphotransferase system-deficient (PTS(-)) derivatives, PB11 and PB12 of strain JM101 that permanently grow slowly on glucose, the inactivation of rpoS resulted in decreased growth rates of 50 and 10%, respectively. Real-time PCR (RT-PCR) analysis confirmed the important role of this sigma factor in the PTS- strains and allowed the identification of 19 genes including almost all the glycolytic genes, not previously reported, to be at least partially dependent on RpoS. The transcription level of gpp, spoT, ppa and ndk whose products are involved in ppGpp metabolism was upregulated in strain PB12 as compared to the parental strains PB11 and JM101. In the PTS- strains, at least three of these genes (gpp, spoT and ppa) were mainly or partially regulated by RpoS which is known to require ppGpp for activation, while only gpp was highly RpoS-dependent in the parental PTS+ strain JM101. The role of RpoS in the transcription of these genes was analyzed and evidence that the expression of this group of genes could be regulated by a common factor in addition to RpoS was discussed.
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología/UNAM, Cuernavaca, México.
authors.forename: Noemí
authors.initials: N
authors.lastname: Flores
authors.forename: Adelfo
authors.initials: A
authors.lastname: Escalante
authors.forename: Ramón
authors.initials: R
authors.lastname: de Anda
authors.forename: José Luis
authors.initials: JL
authors.lastname: Báez-Viveros
authors.forename: Enrique
authors.initials: E
authors.lastname: Merino
authors.forename: Bernardo
authors.initials: B
authors.lastname: Franco
authors.forename: Dimitris
authors.initials: D
authors.lastname: Georgellis
authors.forename: Guillermo
authors.initials: G
authors.lastname: Gosset
authors.forename: Francisco
authors.initials: F
authors.lastname: Bolívar
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics* / Q000378:metabolism; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D012808:Sigma Factor / Q000235:genetics* / Q000502:physiology; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C027627:guanosine-3',5'-bis(diphosphate) 3'-pyrophosphatase; D011755:Pyrophosphatases