The pho regulon of Shigella flexneri.
Growth of Escherichia coli K-12 in low-phosphate conditions results in the induction of the synthesis of many proteins, including the outer membrane porin PhoE, alkaline phosphatase, and the Pst system for the transport of phosphate (P1). This response is controlled by a two-component regulatory system of which PhoB and PhoR are the response-regulator and the sensor/kinase, respectively. When Shigella flexneri was starved for P1, neither PhoE nor alkaline phosphatase was produced. However, induction of the synthesis of the PstS protein was observed, indicating that S. flexneri contains a functional PhoB/PhoR regulatory system. Consistent with this notion, the introduction of the E. coli phoA gene in S. flexneri resulted in the induction of alkaline phosphatase synthesis under phosphate limitation. However, introduction of phoE on a plasmid did not lead to the expression of PhoE protein, indicating that S. flexneri PhoB does not recognize the phoE promoter region. The phoB gene was cloned and sequenced and in the deduced amino acid sequence two deviations from that of E. coli PhoB were detected. Site-directed mutagenesis revealed that one of these deviations, i.e. Leu-172, which is Arg in E. coli PhoB, is responsible for the lack of expression of the PhoE protein in S. flexneri.
Scholten
M
M
Department of Molecular Cell Biology, Utrecht University, The Netherlands.
Janssen
R
R
Bogaarts
C
C
van Strien
J
J
Tommassen
J
J
D000469:Alkaline Phosphatase / Q000235:genetics* / Q000502:physiology; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D033902:Periplasmic Binding Proteins; D028044:Phosphate-Binding Proteins; D010710:Phosphates / Q000378:metabolism / Q000494:pharmacology*; D018272:Porins / Q000235:genetics* / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics* / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D018085:Regulon; D016415:Sequence Alignment; D017385:Sequence Homology; D012763:Shigella flexneri / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D013045:Species Specificity; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology
D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D033902:Periplasmic Binding Proteins; D028044:Phosphate-Binding Proteins; D010710:Phosphates; D018272:Porins; C090133:PstS protein, E coli; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C061278:PhoB protein, Bacteria; C061279:PhoR protein, Bacteria; C082922:PhoE protein, E coli; D011494:Protein Kinases; D000469:Alkaline Phosphatase