title: Protein phosphatase 2A is involved in hyphal growth of Neurospora crassa.
abstract: Cantharidin and calyculin A, natural toxins that are inhibitors of protein phosphatases 1 and 2A (PPI and PP2A, respectively). inhibit Neurospora crassa hyphal growth. When N. crassa was grown in the presence of either drug, abnormalities were observed at hyphal tips. In addition, both drugs induced an increase in hyphal branching. Cantharidin inhibited N. crassa hyphal growth in a temperature-dependent manner, as the effect of the drug was more pronounced at 34 degrees C than at 25 degrees C. In addition to the drug-mediated inhibition of phosphatase activity, a genetic approach was used to determine the phenotypic consequences of reduced PP2A activity. Two strains with subnormal PP2A activity were constructed. The first, in which the original pph-1 gene (encoding the PP2A catalytic subunit) was replaced with an ectopically integrated copy of pph-1, exhibited lower levels of pph-1 transcript, lower PP2A activity and increased sensitivity to cantharidin. Similarly, in a second strain, in which the pph-1 gene was cloned in an antisense orientation downstream of the inducible isocitrate lyase promoter, lower levels of pph-1 transcript, as well as of PP2A activity, and a reduction in hyphal growth were observed. The results of this study indicate that PP2A, and probably other Ser/Thr phosphatases, are involved in the regulation of hyphal growth in N. crassa.
authors.affiliation: Department of Plant Pathology and Microbiology, Otto Warburg Center for Agricultural Biotechnology, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: E
authors.initials: E
authors.lastname: Yatzkan
authors.forename: B
authors.initials: B
authors.lastname: Szöor
authors.forename: Z
authors.initials: Z
authors.lastname: Fehér
authors.forename: V
authors.initials: V
authors.lastname: Dombrádi
authors.forename: O
authors.initials: O
authors.lastname: Yarden
mesh_terms: D016375:Antisense Elements (Genetics); D015152:Blotting, Northern; D015139:Blotting, Southern; D002193:Cantharidin / Q000494:pharmacology*; D020134:Catalytic Domain / Q000235:genetics / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007522:Isocitrate Lyase / Q000235:genetics; D008387:Marine Toxins; D016254:Mutagenesis, Insertional; D009492:Neurospora crassa / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development*; D010080:Oxazoles / Q000494:pharmacology*; D010641:Phenotype; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D054648:Protein Phosphatase 2; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature
chemical_list: D016375:Antisense Elements (Genetics); D004791:Enzyme Inhibitors; D008387:Marine Toxins; D010080:Oxazoles; D011500:Protein Synthesis Inhibitors; C059041:calyculin A; D003513:Cycloheximide; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D007522:Isocitrate Lyase; D002193:Cantharidin