Evidence against the physiological role of acetyl phosphate in the phosphorylation of the ArcA response regulator in Escherichia coli

2009 ◽  
Vol 47 (5) ◽  
pp. 657-662 ◽  
Author(s):  
Xueqiao Liu ◽  
Gabriela R. Peña Sandoval ◽  
Barry L. Wanner ◽  
Won Seok Jung ◽  
Dimitris Georgellis ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Response Regulator ◽  
Physiological Role ◽  
Acetyl Phosphate

scholarly journals Escherichia coli NsrR Regulates a Pathway for the Oxidation of 3-Nitrotyramine to 4-Hydroxy-3-Nitrophenylacetate

2008 ◽  
Vol 190 (18) ◽  
pp. 6170-6177 ◽  
Author(s):  
Linda D. Rankin ◽  
Diane M. Bodenmiller ◽  
Jonathan D. Partridge ◽  
Shirley F. Nishino ◽  
Jim C. Spain ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Physiological Role ◽  
Growth Conditions ◽  
Growth Defect ◽  
E Coli ◽  
Mutant Phenotypes ◽  
Culture Supernatants ◽  
Chip Chip

ABSTRACT Chromatin immunoprecipitation and microarray (ChIP-chip) analysis showed that the nitric oxide (NO)-sensitive repressor NsrR from Escherichia coli binds in vivo to the promoters of the tynA and feaB genes. These genes encode the first two enzymes of a pathway that is required for the catabolism of phenylethylamine (PEA) and its hydroxylated derivatives tyramine and dopamine. Deletion of nsrR caused small increases in the activities of the tynA and feaB promoters in cultures grown on PEA. Overexpression of nsrR severely retarded growth on PEA and caused a marked repression of the tynA and feaB promoters. Both the growth defect and the promoter repression were reversed in the presence of a source of NO. These results are consistent with NsrR mediating repression of the tynA and feaB genes by binding (in an NO-sensitive fashion) to the sites identified by ChIP-chip. E. coli was shown to use 3-nitrotyramine as a nitrogen source for growth, conditions which partially induce the tynA and feaB promoters. Mutation of tynA (but not feaB) prevented growth on 3-nitrotyramine. Growth yields, mutant phenotypes, and analyses of culture supernatants suggested that 3-nitrotyramine is oxidized to 4-hydroxy-3-nitrophenylacetate, with growth occurring at the expense of the amino group of 3-nitrotyramine. Accordingly, enzyme assays showed that 3-nitrotyramine and its oxidation product (4-hydroxy-3-nitrophenylacetaldehyde) could be oxidized by the enzymes encoded by tynA and feaB, respectively. The results suggest that an additional physiological role of the PEA catabolic pathway is to metabolize nitroaromatic compounds that may accumulate in cells exposed to NO.

scholarly journals Survival of uropathogenic Escherichia coli in the murine urinary tract is dependent on OmpR

Microbiology ◽  
2009 ◽  
Vol 155 (6) ◽  
pp. 1832-1839 ◽  
Author(s):  
William R. Schwan
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Phosphorylation Site ◽  
Regulatory System ◽  
Growth Defect ◽  
Wild Type ◽  
Log Reduction

Uropathogenic Escherichia coli (UPEC) can grow in environments with significantly elevated osmolarities, such as murine and human urinary tracts. OmpR is the response regulator part of a two-component OmpR–EnvZ regulatory system that responds to osmotic stresses. To determine the role of OmpR in UPEC survival, a ΔompR mutant was created in the UPEC clinical isolate NU149. The ΔompR mutant had a growth defect compared with the wild-type strain under osmotic stress conditions; this defect was complemented by the full-length ompR gene on a plasmid, but not with a mutant OmpR with an alanine substitution for aspartic acid at the phosphorylation site at position 55. Furthermore, the ΔompR mutant displayed up to 2-log reduction in bacterial cell numbers in murine bladders and kidneys compared with wild-type bacteria after 5 days of infection. The ability of the bacteria to survive was restored to wild-type levels when the ΔompR mutant strain was complemented with wild-type ompR, but not when the alanine-substituted ompR gene was used. This study has fulfilled molecular Koch's postulates by showing the pivotal role OmpR plays in UPEC survival within the murine urinary tract.

scholarly journals The nrfA and nirB Nitrite Reductase Operons in Escherichia coli Are Expressed Differently in Response to Nitrate than to Nitrite

2000 ◽  
Vol 182 (20) ◽  
pp. 5813-5822 ◽  
Author(s):  
Henian Wang ◽  
Robert P. Gunsalus
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Nitrite Reductase ◽  
Transcriptional Activation ◽  
Response Regulator ◽  
Physiological Role ◽  
Growth Conditions ◽  
Potent Inducer ◽  
Culture Techniques ◽  
Nitrite Reductase Gene

ABSTRACT Escherichia coli possesses two distinct nitrite reductase enzymes encoded by the nrfA and nirBoperons. The expression of each operon is induced during anaerobic cell growth conditions and is further modulated by the presence of either nitrite or nitrate in the cells' environment. To examine how each operon is expressed at low, intermediate, and high levels of either nitrate or nitrite, anaerobic chemostat culture techniques were employed using nrfA-lacZ and nirB-lacZ reporter fusions. Steady-state gene expression studies revealed a differential pattern of nitrite reductase gene expression where optimalnrfA-lacZ expression occurred only at low to intermediate levels of nitrate and where nirB-lacZ expression was induced only by high nitrate conditions. Under these conditions, the presence of high levels of nitrate suppressed nrfA gene expression. While either NarL or NarP was able to inducenrfA-lacZ expression in response to low levels of nitrate, only NarL could repress at high nitrate levels. The different expression profile for the alternative nitrite reductase operon encoded by nirBDC under high-nitrate conditions was due to transcriptional activation by either NarL or NarP. Neither response regulator could repress nirB expression. Nitrite was also an inducer of nirB and nrfA gene expression, but nitrate was always the more potent inducer by >100-fold. Lastly, since nrfA operon expression is only induced under low-nitrate concentrations, the NrfA enzyme is predicted to have a physiological role only where nitrate (or nitrite) is limiting in the cell environment. In contrast, the nirB nitrite reductase is optimally synthesized only when nitrate or nitrite is in excess of the cell's capacity to consume it. Revised regulatory schemes are presented for NarL and NarP in control of the two operons.

scholarly journals Role of the response regulator RssB in sigmaS recognition and initiation of sigmaS proteolysis in Escherichia coli

2001 ◽  
Vol 40 (6) ◽  
pp. 1381-1390 ◽  
Author(s):  
Eberhard Klauck ◽  
Maren Lingnau ◽  
Regine Hengge-Aronis
Keyword(s):  
Escherichia Coli ◽  
Response Regulator

The direct synthesis of phospho enol pyruvate from pyruvate by Escherichia coli

1967 ◽  
Vol 168 (1012) ◽  
pp. 263-280 ◽  
Keyword(s):  
Escherichia Coli ◽  
Inorganic Phosphate ◽  
Direct Synthesis ◽  
Physiological Role ◽  
Wild Type ◽  
Pyruvate Kinase Activity ◽  
Ph Values ◽  
Direct Formation ◽  
Pyruvate Synthase

Extracts of Escherichia coli are shown to contain an enzyme system which in the presence of Mg 2+ catalyses the direct formation of phospho enol pyruvate from pyruvate and ATP with concomitant formation of AMP and inorganic phosphate. This enzyme, which has been designated 'phospho enol pyruvate synthase' ( PEP -synthase) has been purified 80-fold and is free of pyruvate kinase activity; PEP synthesis proceeded most rapidly at pH 8 to 8.5. At pH values between 6.2 and 7.5 the enzyme can catalyse the formation of ATP and pyruvate from PEP , AMP and inorganic phosphate; if arsenate is used instead of phosphate, pyruvate and ADP are produced instead. Studies of the enzymic formation of PEP with ATP specifically labelled with 32 P, and of the reverse reaction with [U -14 C] AMP , suggest that the PEP -synthase reaction involves the transfer of a pyrophosphoryl-group. The physiological role of PEP -synthase has been demonstrated with mutants of E. coli devoid of the enzyme: in contrast to wild-type organisms, such mutants neither grow on pyruvate, lactate or alanine, nor form glycogen from lactate. It is thus concluded that PEP -synthase plays an important role in the anaplerotic and the biosynthetic reactions which enable the organisms to grow on pyruvate as sole carbon source.

scholarly journals RpoS Proteolysis Is Regulated by a Mechanism That Does Not Require the SprE (RssB) Response Regulator Phosphorylation Site

2004 ◽  
Vol 186 (21) ◽  
pp. 7403-7410 ◽  
Author(s):  
Celeste N. Peterson ◽  
Natividad Ruiz ◽  
Thomas J. Silhavy
Keyword(s):  
Escherichia Coli ◽  
Sigma Factor ◽  
Response Regulator ◽  
Phosphorylation Site ◽  
Carbon Starvation ◽  
Logarithmic Phase ◽  
Acetyl Phosphate ◽  
Wild Type ◽  
Basal Activity ◽  
Sigma Factor Rpos

ABSTRACT In Escherichia coli the response regulator SprE (RssB) facilitates degradation of the sigma factor RpoS by delivering it to the ClpXP protease. This process is regulated: RpoS is degraded in logarithmic phase but becomes stable upon carbon starvation, resulting in its accumulation. Because SprE contains a CheY domain with a conserved phosphorylation site (D58), the prevailing model posits that this control is mediated by phosphorylation. To test this model, we mutated the conserved response regulator phosphorylation site (D58A) of the chromosomal allele of sprE and monitored RpoS levels in response to carbon starvation. Though phosphorylation contributed to the SprE basal activity, we found that RpoS proteolysis was still regulated upon carbon starvation. Furthermore, our results indicate that phosphorylation of wild-type SprE occurs by a mechanism that is independent of acetyl phosphate.

scholarly journals Role of RcsF in Signaling to the Rcs Phosphorelay Pathway in Escherichia coli

2005 ◽  
Vol 187 (19) ◽  
pp. 6770-6778 ◽  
Author(s):  
Nadim Majdalani ◽  
Michael Heck ◽  
Valerie Stout ◽  
Susan Gottesman
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Small Rna ◽  
Kinase Activity ◽  
Response Regulator ◽  
Constitutive Expression ◽  
Activation Mechanism ◽  
Sensor Kinase ◽  
High Level

ABSTRACT The rcs phosphorelay pathway components were originally identified as regulators of capsule synthesis. In addition to the transmembrane sensor kinase RcsC, the RcsA coregulator, and the response regulator RcsB, two new components have been characterized, RcsD and RcsF. RcsD, the product of the yojN gene, now renamed rcsD, acts as a phosphorelay between RcsC and RcsB. Transcription of genes for capsule synthesis (cps) requires both RcsA and RcsB; transcription of other promoters, including that for the small RNA RprA, requires only RcsB. RcsF was described as an alternative sensor kinase for RcsB. We have examined the role of RcsF in the activation of both the rprA and cps promoters. We find that a number of signals that lead to activation of the phosphorelay require both RcsF and RcsC; epistasis experiments place RcsF upstream of RcsC. The RcsF sequence is characteristic of lipoproteins, consistent with a role in sensing cell surface perturbation and transmitting this signal to RcsC. Activation of RcsF does not require increased transcription of the gene, suggesting that modification of the RcsF protein may act as an activating signal. Signals from RcsC require RcsD to activate RcsB. Sequencing of an rcsC allele, rcsC137, that leads to high-level constitutive expression of both cps and rprA suggests that the response regulator domain of RcsC plays a role in negatively regulating the kinase activity of RcsC. The phosphorelay and the variation in the activation mechanism (dependent upon or independent of RcsA) provide multiple steps for modulating the output from this system.

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