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Imaging G-protein Coupled Receptor (GPCR)-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum
Published on: September 20, 2011
Phosphodiesterase in Dictyostelium discoideum and the chemotactic response to cyclic adenosine monophosphate
Science (New York, N.Y.)
|March 3, 1972
Abstract:
A phosphodiesterase with a low Michaelis constant for cyclic adenosine monophosphate was found in the membrane fraction of the cellular slime mold. This activity was highest during the aggregation stage. Enzyme with similar properties was also secreted by the cells. Dithiothreitol inhibited both enzymes and potentiated the cellular response to cyclic adenosine monophosphate.
Insights
Cellular slime molds possess a phosphodiesterase enzyme that breaks down cyclic adenosine monophosphate, particularly during aggregation. This enzyme, also secreted by cells, is affected by dithiothreitol.
Area of Science:
- Biochemistry
- Cell Biology
- Developmental Biology
Background:
- Cyclic adenosine monophosphate (cAMP) is a crucial second messenger in cellular signaling.
- Phosphodiesterases (PDEs) regulate intracellular cAMP levels by catalyzing its hydrolysis.
- Cellular slime molds exhibit complex developmental behaviors, including aggregation, regulated by cAMP.
Purpose of the Study:
- To identify and characterize phosphodiesterase activity in cellular slime molds.
- To investigate the role of this enzyme during the aggregation stage.
- To examine the effect of dithiothreitol on enzyme activity and cellular response.
Main Methods:
- Enzyme assays were performed on membrane fractions of cellular slime molds.
- Analysis of enzyme activity during different developmental stages, focusing on aggregation.
- Investigation of secreted enzyme activity.
- Dithiothreitol treatment to assess its modulatory effects.
Main Results:
- A phosphodiesterase with a low Michaelis constant for cAMP was identified in the membrane fraction.
- Enzyme activity peaked during the aggregation stage of cellular slime mold development.
- Similar phosphodiesterase activity was detected in the extracellular medium, indicating secretion.
- Dithiothreitol inhibited both membrane-bound and secreted enzymes and enhanced cellular responsiveness to cAMP.
Conclusions:
- Cellular slime molds possess a cAMP-specific phosphodiesterase that plays a significant role during aggregation.
- The enzyme is both intracellular (membrane-bound) and extracellular (secreted).
- Dithiothreitol modulates both enzyme activity and cAMP-mediated cellular responses, suggesting a regulatory mechanism.
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