scholarly journals Steady-state measurements of Escherichia coli sodium and proton potentials at alkaline pH support the hypothesis of electrogenic antiport.

1990 ◽  
Vol 265 (16) ◽  
pp. 9247-9250
Author(s):  
J W Pan ◽  
R M Macnab
Keyword(s):  
Escherichia Coli ◽  
Steady State ◽  
Alkaline Ph

scholarly journals CpxP, a Stress-Combative Member of the Cpx Regulon

1998 ◽  
Vol 180 (4) ◽  
pp. 831-839 ◽  
Author(s):  
Paul N. Danese ◽  
Thomas J. Silhavy
Keyword(s):  
Escherichia Coli ◽  
Envelope Protein ◽  
Periplasmic Protein ◽  
Dependent Manner ◽  
Alkaline Ph ◽  
Signal Transduction System ◽  
Two Component ◽  
Mutant Strains ◽  
Alkaline Conditions ◽  
Two Component Signal Transduction

ABSTRACT The CpxA/R two-component signal transduction system ofEscherichia coli can combat a variety of extracytoplasmic protein-mediated toxicities. The Cpx system performs this function, in part, by increasing the synthesis of the periplasmic protease, DegP. However, other factors are also employed by the Cpx system for this stress-combative function. In an effort to identify these remaining factors, we screened a collection of random lacZ operon fusions for those fusions whose transcription is regulated by CpxA/R. Through this approach, we have identified a new locus,cpxP, whose transcription is stimulated by activation of the Cpx pathway. cpxP specifies a periplasmic protein that can combat the lethal phenotype associated with the synthesis of a toxic envelope protein. In addition, we show that cpxPtranscription is strongly induced by alkaline pH in a CpxA-dependent manner and that cpxP and cpx mutant strains display hypersensitivity to growth in alkaline conditions.

Effects of E. coli sepsis and myocardial depressant factor on interval-force relations in dog ventricle

1993 ◽  
Vol 264 (5) ◽  
pp. H1402-H1410 ◽  
Author(s):  
P. Jha ◽  
H. Jacobs ◽  
D. Bose ◽  
R. Wang ◽  
J. Yang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Steady State ◽  
Sarcoplasmic Reticulum ◽  
Calcium Metabolism ◽  
Calcium Content ◽  
Left Ventricular ◽  
Muscle Preparation ◽  
E Coli ◽  
Calcium Availability ◽  
Fractional Release

We examined whether depressed left ventricular (LV) contractility during Escherichia coli sepsis in dogs was due to a decrease in the fractional release of calcium from the sarcoplasmic reticulum (SR) or a reduction in calcium content in this organelle. To indirectly assess SR calcium availability in a right ventricular (RV) trabecular muscle preparation, we utilized functional indexes of cellular myocardial calcium metabolism, which included rapid-cooling contracture (RCC), an indicator of SR calcium content, and postrest contraction (PRC), an index of calcium availability from the release compartment of the SR. Measurements were made during steady-state stimulation at 0.5 and 1.5 Hz, during which time rest intervals of 30-240 s were periodically imposed. SR calcium availability was measured in RV trabeculae of dogs subjected to 4 h of E. coli sepsis and was compared with calcium availability measured in nonseptic dogs. We further characterized a filterable cardiodepressant substance (FCS), which has been previously shown to be associated with LV depression in this model, to determine whether it produced changes in calcium metabolism similar to those found in sepsis. The results showed that calcium availability from the SR of septic dogs was not impaired. Furthermore, FCS was found in the 10,000- to 30,000-mol wt fraction of plasma and produced changes in PRC in canine trabeculae that were similar to those produced during sepsis. We conclude that, as assessed by PRC and RCC, SR calcium content and release are not impaired in sepsis.

scholarly journals Gene activities for ribosomal components in Escherichia coli B/r

1975 ◽  
Vol 150 (3) ◽  
pp. 469-475 ◽  
Author(s):  
H Bremer ◽  
P P Dennis
Keyword(s):  
Escherichia Coli ◽  
Steady State ◽  
Ribosomal Rna ◽  
Growth Rates ◽  
Ribosomal Proteins ◽  
Rrna Genes ◽  
Steady State Growth ◽  
State Growth ◽  
Escherichia Coli B

The relative transcriptional activities of genes coding for ribosomal RNA (rRNA) and ribosomal proteins (r-proteins) at a steady-state growth rates ranging from 0.65 to 2.1 doublings/h can be estimated from previous measurements of the synthesis rates of stable and unstable RNA (Pato & von Meyenburg, 1970; Nierlich, 1972a,b; Bremer et al., 1973; Dennis & Bremer, 1973b, 1974b) and ribosomal proteins (Schleif, 1967; Dennis & Bremer, 1974a). Comparison of these transcriptional activities suggests that the expression of the r-protein genes and rRNA genes is controlled seperately.

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