Heterotrimeric G-protein and signal transduction in the nematode-trapping fungus Arthrobotrys dactyloides
| Autor: | Pui-Jen Tsai, Chan-San Hsu, Tsung-Hsien Chen, Yi-Feng Ho, Na-Sheng Lin |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Calmodulin
G protein Hydrostatic pressure Wasp Venoms Plant Science Inositol 1 4 5-Trisphosphate Pertussis toxin Aquaporins Heterotrimeric G protein Microsomes Genetics Hydrostatic Pressure Virulence Factors Bordetella Antibodies Fungal biology Activator (genetics) ADP-Ribosylation Factors Neomycin Heterotrimeric GTP-Binding Proteins Immunohistochemistry Cell biology Biochemistry Pertussis Toxin Mastoparan Mercuric Chloride biology.protein Intercellular Signaling Peptides and Proteins Calcium Mitosporic Fungi Signal transduction Peptides Signal Transduction |
| Zdroj: | Planta. 212(5-6) |
| ISSN: | 0032-0935 |
| Popis: | The fungus Arthrobotrys dactyloides produces specialized constricting rings to trap and then consume nematodes. The signal transduction pathway involved in the nematode-trapping process was examined. Mastoparan, an activator of G-protein, had a stimulatory effect on the inflation of ring cells, whereas a G-protein inhibitor, pertussis toxin, prevented ring-cell expansion. The 40-kDa G alpha of heterotrimeric G-proteins was specifically ADP-ribosylated by pertussis toxin. Using an antibody specific to the 35-kDa subunit G beta, we showed that immunogold-labeled G beta was more concentrated in ring cells than in the hyphae. In the absence of nematodes, the rings could be inflated by either pressurizing the culture in a syringe, raising intracellular Ca2+ concentrations, or adding warm water. We used these methods to reveal differences in responses to antagonists. The results support a model in which the pressure exerted by a nematode on the ring activates G-proteins in the ring cells. The activation leads to an increase in cytoplasmic Ca2+, activation of calmodulin, and finally the opening of water channels. The ring cells expand to constrict the ring and thus immobilize the nematode. |
| Databáze: | OpenAIRE |
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