Related Experiment Video
Updated: Jul 6, 2026
10:24
Cytosolic Calcium Measurements in Renal Epithelial Cells by Flow Cytometry
Published on: October 28, 2014
pH and monovalent cations regulate cytosolic free Ca(2+) in E. coli
Riffat Naseem1, I Barry Holland, Annick Jacq
1Department of Medical Biochemistry and Immunology, Tenovus Building, Cardiff University, Heath Park, Cardiff, UK.
Biochimica Et Biophysica Acta
|March 18, 2008
Summary
pH and monovalent cations regulate calcium (Ca2+) in E. coli by controlling influx and efflux. This study reveals novel insights into bacterial ion transport, crucial for adapting to diverse environments like the gut and seawater.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Cytosolic free Ca(2+) is a critical second messenger in many cellular processes.
- Understanding Ca(2+) regulation in bacteria is essential for their adaptation to various environments.
Purpose of the Study:
- To investigate the roles of pH and monovalent cations in regulating cytosolic free Ca(2+) in E. coli.
- To identify the mechanisms and pathways involved in bacterial Ca(2+) transport.
Main Methods:
- Utilized aequorin to monitor cytosolic free Ca(2+) levels in E. coli.
- Performed experiments manipulating external pH, Ca(2+), Na(+), K(+), and osmotic pressure.
- Examined Ca(2+) transport in wild-type and knockout strains (chaA and yrbG).
Main Results:
- pH significantly impacts Ca(2+) influx, with higher levels at alkaline pH.
- Monovalent cations (Na+, K+) stimulate Ca(2+) efflux, suggesting competition for influx channels.
- Neither ChaA nor YrbG appear to be major regulators of cytosolic Ca(2+) in E. coli.
Conclusions:
- Bacterial Ca(2+) transport mechanisms are distinct from eukaryotes, with lower ion flux rates.
- The findings necessitate new mathematical models for bacterial ion movement.
- This research has implications for E. coli's adaptation to environments like the gut and marine settings.
Related Concept Videos
01:27Feedback Regulation of Calcium Concentration
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
01:28pH Regulation in Cells
pH plays a critical role in maintaining normal cellular activities. It helps maintain the structure and function of various proteins, dictates the charge on cellular membranes, and is crucial for metabolic reactions inside the cell. Moreover, cells use the energy from the proton motive force to generate ATP.
Cytosolic pH
Under physiological conditions, the cytosolic pH is slightly more acidic than the extracellular pH. However, cells must prevent further acidification of their cytosol to...
Cytosolic pH
Under physiological conditions, the cytosolic pH is slightly more acidic than the extracellular pH. However, cells must prevent further acidification of their cytosol to...
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
01:33Introduction to Electrolytes
In humans, electrolytes play a vital role in various physiological processes. Balancing electrolyte levels is essential for normal body functions; their imbalance can be life-threatening. The major electrolytes include sodium, potassium, chloride, calcium, phosphate, and bicarbonate. They are primarily involved in physiological processes, such as nerve signal transmission, membrane trafficking, muscle contraction, buffering body fluids, and balancing water levels in the body.
Role of Sodium
One...
Role of Sodium
One...
01:09GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...
01:27Chemotaxis in E. coli
Chemotaxis in Escherichia coli is a sensory-driven motility mechanism that enables bacteria to navigate chemical gradients, moving toward beneficial environments while avoiding harmful conditions. This process relies on a signal transduction system integrating external chemical cues with flagellar motor control.Chemoreceptors and Signal DetectionE. coli detects chemical gradients through methyl-accepting chemotaxis proteins (MCPs), which are membrane-bound chemoreceptors that sense attractants...