Electrical Phenotypes of Calcium Transport Mutant Strains of a Filamentous Fungus, Neurospora crassa
| Autor: | Roger R. Lew, Ahmed Hamam |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Cytoplasm
Vacuolar Proton-Translocating ATPases Genes Fungal Mutant Hyphae Hyphal tip chemistry.chemical_element Calcium Microbiology Membrane Potentials Neurospora crassa Fungal Proteins Culture Techniques Extracellular Homeostasis Calcium Signaling Molecular Biology Fungal protein Cyanides biology Cell Membrane Wild type Articles General Medicine respiratory system biology.organism_classification Molecular biology Culture Media Mitochondria Phenotype chemistry Biochemistry Mechanosensitive channels Microelectrodes |
| Zdroj: | Eukaryotic Cell. 11:694-702 |
| ISSN: | 1535-9786 1535-9778 |
| Popis: | We characterized the electrical phenotypes of mutants with mutations in genes encoding calcium transporters—a mechanosensitive channel homolog ( MscS ), a Ca 2+ /H + exchange protein ( cax ), and Ca 2+ -ATPases ( nca-1 , nca-2 , nca-3 )—as well as those of double mutants (the nca-2 cax , nca-2 nca-3 , and nca-3 cax mutants). The electrical characterization used dual impalements to obtain cable-corrected current-voltage measurements. Only two types of mutants (the MscS mutant; the nca-2 mutant and nca-2 -containing double mutants) exhibited lower resting potentials. For the nca-2 mutant, on the basis of unchanged conductance and cyanide-induced depolarization of the potential, the cause is attenuated H + -ATPase activity. The growth of the nca-2 mutant-containing strains was inhibited by elevated extracellular Ca 2+ levels, indicative of lesions in Ca 2+ homeostasis. However, the net Ca 2+ effluxes of the nca-2 mutant, measured noninvasively with a self-referencing Ca 2+ -selective microelectrode, were similar to those of the wild type. All of the mutants exhibited osmosensitivity similar to that of the wild type (the turgor of the nca-2 mutant was also similar to that of the wild type), suggesting that Ca 2+ signaling does not play a role in osmoregulation. The hyphal tip morphology and tip-localized mitochondria of the nca-2 mutant were similar to those of the wild type, even when the external [Ca 2+ ] was elevated. Thus, although Ca 2+ homeostasis is perturbed in the nca-2 mutant (B. J. Bowman et al., Eukaryot. Cell 10:654–661, 2011), the phenotype does not extend to tip growth or to osmoregulation but is revealed by lower H + -ATPase activity. |
| Databáze: | OpenAIRE |
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