Nucleotide pool in pho regulon mutants and alkaline phosphatase synthesis in Escherichia coli

Rao, Narayana N.; E, Wang; Yashphe, Jacob; Torriani, Annamaria

doi:10.1128/jb.166.1.205-211.1986

Cited by 24 publications

(16 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Given that ppGpp levels increase following depletion of nutrients, it would be surprising if ppGpp levels remained unchanged as cells enter stationary phase in LB medium. In addition, phosphate starvation has been reported to result in no increase in ppGpp (8,26). The us accumulation reported here has led us to reexamine ppGpp accumulation following phosphate starvation.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis of the stationary-phase sigma factor sigma s is positively regulated by ppGpp

et al. 1993

View full text Add to dashboard Cite

Strains of Escherichia coli which lack detectable guanosine 3',5'-bispyrophosphate (ppGpp) display a pleiotropic phenotype that in some respects resembles that of rpoS (katF) mutants. This led us to examine whether ppGpp is a positive regulator of sigma s synthesis. sigma s is a stationary-phase-specific sigma factor that is encoded by the rpoS gene. We found that a ppGpp-deficient strain is defective in sigma s synthesis as cells enter stationary phase in a rich medium, as judged by immunoblots. Under more-defined conditions we found that the stimulation of sigma s synthesis following glucose, phosphate, or amino acid starvation of wild-type strains is greatly reduced in a strain lacking ppGpp. The failure of ppGpp-deficient strains to synthesize sigma s in response to these starvation regimens could indicate a general defect in gene expression rather than a specific dependence of rpoS expression on ppGpp. We therefore tested the effect of artificially elevated ppGpp levels on sigma s synthesis either with mutations that impair ppGpp decay or by gratuitously inducing ppGpp synthesis with a Ptac::relA fusion. In both instances, we observed enhanced sigma s synthesis. Apparently, ppGpp can activate sigma s synthesis under conditions of nutrient sufficiency as well as during entry into stationary phase. This finding suggests that changes in ppGpp levels function both as a signal of imminent stationary phase and as a signal of perturbations in steady-state growth.

show abstract

Section: Methodsmentioning

confidence: 99%

“…Phosphate limitation is, however, reported as having at most only mild effects on ppGpp levels (16,18,26).…”

mentioning

confidence: 99%

Synthesis of the stationary-phase sigma factor sigma s is positively regulated by ppGpp

et al. 1993

View full text Add to dashboard Cite

show abstract

“…We named it ugpQ. It is interesting that the last genes of other binding proteindependent transport system operons, such as the rbs (ribose [16]) and pst (phosphate [34,42]) systems, also code for an enzyme whose activity is dispensable for transport. Isolation of lacZ fusions in the ugp operon leads us to the following conclusions.…”

Section: Fig 2 Hydrolysis Of Different Glycerophosphoryl Diesters mentioning

confidence: 99%

Characteristics of a ugp-encoded and phoB-dependent glycerophosphoryl diester phosphodiesterase which is physically dependent on the ugp transport system of Escherichia coli

Brzoska

Boos

1988

J Bacteriol

View full text Add to dashboard Cite

The ugp-encoded transport system ofEscherichia coli accumulates sn-glycerol-3-phosphate with high affinity; it is binding protein mediated and part of the pho regulon. Here, we report that glycerophosphoryl diesters (deacylated phospholipids) are also high-affinity substrates for the ugp-encoded system. The diesters are not taken up in an unaltered form but are hydrolyzed during transport to sn-glycerol-3-phosphate plus the corresponding alcohols. The enzyme responsible for this reaction is not essential for the translocation of sn-glycerol-3-pbosphate or for the glycerophosphoryl diesters but can only hydrolyze diesters that are in the process of being transported. Diesters in the periplasm or in the cytoplasm were not recognized, and no enzymatic activity could be detected in cellular extracts. The enzyme is encoded by the last gene in the ugp operon, termed ugpQ. The product of the ugpQ gene, expressed in mniiicells, has an apparent molecular weight of 17,500. We present evidence that only one major phoB-dependent promoter controls afl ugp genes.sn-Glycerol-3-phosphate (G3P) can be utilized by Escherichia coli as the sole source of carbon (24) and of phosphate (36). Being an essential precursor for phospholipids, a sufficient concentration of G3P must be maintained by the cell (6, 33). In the absence of exogenous G3P, this essential intermediate is supplied by the reduction of dihydroxyacetone phosphate via an NADH-linked dehydrogenase, an enzyme that is tightly regulated by G3P (7). The major uptake system for G3P in the presence of Pi, which represses (43) the pho regulon, is the glpT-dependent transport system (22). G3P transport via the glpT-dependent transport system is mediated by exchange against intracellular Pi (1,13). glpT is a member of the glp regulon, which consists of several genes organized into several operons, the products of which are responsible for uptake and catabolism of glycerol and G3P (24). The operon containing glpT harbors a second gene, glpQ, distal to glpT, that codes for a periplasmic glycerophosphoryl diester phosphodiesterase, an enzyme that hydrolyzes deacylated phospholipids to G3P and the corresponding alcohols (20). The glp regulon is induced by elevated levels of cytoplasmic G3P, the induction being controlled by a cytoplasmic repressor, the product of the glpR gene (23). The catabolic nature of the glp regulon is demonstrated by its dependence on the cAMP-catabolite gene activator protein regulatory circuit (24).

show abstract

“…In mutants with a defective phosphate-specific transport system, a high intracellular Pi level can also be maintained by another uptake system, the phosphate inorganic transport system [86], while these mutants are still derepressed for the pho regulon. It was recently shown that the intracellular nucleotide pools are changed upon Pi limitation and that the phoU gene is involved in these alterations [87]. These nucleotides are most likely the actual effectors of thephoR gene product [88].…”

Section: Inducible Major Outer Membrane Proteinsmentioning

confidence: 99%

Permeation of hydrophilic molecules through the outer membrane of gram‐negativ bacteria

Benz

Bauer

1988

European Journal of Biochemistry

274

179

View full text Add to dashboard Cite

Nucleotide pool in pho regulon mutants and alkaline phosphatase synthesis in Escherichia coli

Cited by 24 publications

References 16 publications

Synthesis of the stationary-phase sigma factor sigma s is positively regulated by ppGpp

Synthesis of the stationary-phase sigma factor sigma s is positively regulated by ppGpp

Characteristics of a ugp-encoded and phoB-dependent glycerophosphoryl diester phosphodiesterase which is physically dependent on the ugp transport system of Escherichia coli

Permeation of hydrophilic molecules through the outer membrane of gram‐negativ bacteria

Contact Info

Product

Resources

About