Heterotrimeric G-proteins of a filamentous fungus regulate cell wall composition and susceptibility to a plant PR-5 protein.
Membrane permeabilizing plant defensive proteins first encounter the fungal cell wall that can harbor specific components that facilitate or prevent access to the plasma membrane. However, signal transduction pathways controlling cell wall composition in filamentous fungi are largely unknown. We report here that the deposition of cell wall constituents that block the action of osmotin (PR-5), an antifungal plant defense protein, against Aspergillus nidulans requires the activity of a heterotrimeric G-protein mediated signaling pathway. The guanidine nucleotide GDPbetaS, that locks G-proteins in a GDP-bound inactive form, inhibits osmotin-induced conidial lysis. A dominant interfering mutation in FadA, the alpha-subunit of a heterotrimeric G-protein, confers resistance to osmotin. A deletion mutation in SfaD, the beta-subunit of a heterotrimeric G-protein also increases osmotin resistance. Aspergillus nidulans strains bearing these mutations also have increased tolerance to SDS, reduced cell wall porosity and increased chitin content in the cell wall.
Coca
M A
MA
Center for Plant Environmental Stress Physiology, 1165 Horticulture Building, Purdue University, West Lafayette, IN 47907-1165, USA.
Damsz
B
B
Yun
D J
DJ
Hasegawa
P M
PM
Bressan
R A
RA
Narasimhan
M L
ML
D001233:Aspergillus nidulans / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D005656:Fungal Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019204:GTP-Binding Proteins; D005800:Genes, Fungal; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010940:Plant Proteins / Q000378:metabolism* / Q000494:pharmacology; D010947:Plants, Toxic; D015398:Signal Transduction; D013873:Thionucleotides / Q000494:pharmacology; D014026:Nicotiana
C102142:FADA protein, Emericella nidulans; D005656:Fungal Proteins; D010940:Plant Proteins; D013873:Thionucleotides; C091553:flbA protein, Aspergillus nidulans; C053376:pathogenesis-related proteins, plant; C073139:osmotin protein, Nicotiana tabacum; D006153:Guanosine Diphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins