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Structure/function studies on the pH-dependent actin-binding protein hisactophilin in Dictyostelium mutants
M Stoeckelhuber1, A A Noegel, C Eckerskorn
1Adolf-Butenandt-Institut/Zellbiologie, Ludwig-Maximilians-Universität, München, Germany.
Journal of Cell Science
|July 1, 1996
Summary
Hisactophilin protein in Dictyostelium discoideum organizes the actin cytoskeleton at the plasma membrane. Overexpression mutants showed resistance to pH changes, suggesting hisactophilin acts as a pH sensor.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Hisactophilin is an actin-binding protein in Dictyostelium discoideum.
- It is a candidate for pH-dependent organization of the actin cytoskeleton at the plasma membrane.
Purpose of the Study:
- To characterize the interaction of hisactophilin with the actin cytoskeleton.
- To investigate the role of hisactophilin in pH-dependent cellular processes.
Main Methods:
- Isolation of hisactophilin overexpression (hisII+) and hisactophilin minus (his-) mutants in Dictyostelium discoideum.
- Gene inactivation and overexpression strategies were employed.
- Biochemical analysis, mass spectrometry, and cellular phenotype assessments under varying pH conditions.
Main Results:
- Hisactophilin II overexpression (hisII+) and gene knockout (his-) mutants were successfully generated.
- Overexpression of hisactophilin II did not affect normal cellular growth, development, or morphology.
- HisII+ cells exhibited increased resistance to cytoplasmic acidification induced by diethylstilbestrol, showing altered F-actin dynamics and plasma membrane behavior.
Conclusions:
- Hisactophilin functions as a pH sensor at the plasma membrane.
- It reversibly connects the membrane with the actin cortical network in response to proton concentration changes.
- Hisactophilin plays a crucial role in cellular adaptation to acidic environments.