title: Involvement of the ribose operon repressor RbsR in regulation of purine nucleotide synthesis in Escherichia coli.
abstract: Escherichia coli is able to utilize d-ribose as its sole carbon source. The genes for the transport and initial-step metabolism of d-ribose form a single rbsDACBK operon. RbsABC forms the ABC-type high-affinity d-ribose transporter, while RbsD and RbsK are involved in the conversion of d-ribose into d-ribose 5-phosphate. In the absence of inducer d-ribose, the ribose operon is repressed by a LacI-type transcription factor RbsR, which is encoded by a gene located downstream of this ribose operon. At present, the rbs operon is believed to be the only target of regulation by RbsR. After Genomic SELEX screening, however, we have identified that RbsR binds not only to the rbs promoter but also to the promoters of a set of genes involved in purine nucleotide metabolism. Northern blotting analysis indicated that RbsR represses the purHD operon for de novo synthesis of purine nucleotide but activates the add and udk genes involved in the salvage pathway of purine nucleotide synthesis. Taken together, we propose that RbsR is a global regulator for switch control between the de novo synthesis of purine nucleotides and its salvage pathway.
authors: Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan.
authors: Tomohiro
authors: T
authors: Shimada
authors: Ayako
authors: A
authors: Kori
authors: Akira
authors: A
authors: Ishihama
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011687:Purines / Q000096:biosynthesis*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012266:Ribose / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D011687:Purines; C489909:RbsR protein, E coli; D012097:Repressor Proteins; D012266:Ribose; C030985:purine