SakA MAP kinase is involved in stress signal transduction, sexual development and spore viability in Aspergillus nidulans.
In eukaryotic cells, environmental stress signals are transmitted by evolutionarily conserved MAPKs, such as Hog1 in the budding yeast Saccharomyces cerevisiae, Spc1 in the fission yeast Schizosaccharomyces pombe and p38/JNK in mammalian cells. Here, we report the identification of the Aspergillus nidulans sakA gene, which encodes a member of the stress MAPK family. The sakA gene is able to complement the S. pombe spc1- defects in both osmo-regulation and cell cycle progression. Moreover, SakA MAPK is activated in response to osmotic and oxidative stress in both S. pombe and A. nidulans. However, in contrast to hog1 and spc1 mutants, the sakA null mutant is not sensitive to high osmolarity stress, indicating a different regulation of the osmostress response in this fungus. On the other hand, the DeltasakA mutant shows development and cell-specific phenotypes. First, it displays premature steA-dependent sexual development. Second, DeltasakA mutant produces asexual spores that are highly sensitive to oxidative and heat shock stress and lose viability upon storage. Indeed, SakA is transiently activated early after induction of conidiation. Our results indicate that SakA MAPK is involved in stress signal transduction and repression of sexual development, and is required for spore stress resistance and survival.
Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México.
Laura
L
Kawasaki
Olivia
O
Sánchez
Kazuhiro
K
Shiozaki
Jesús
J
Aguirre
D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary; D018869:Heat-Shock Response; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009994:Osmolar Concentration; D018384:Oxidative Stress; D010766:Phosphorylation; D012568:Schizosaccharomyces / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013172:Spores, Fungal
D017931:DNA Primers; D018076:DNA, Complementary; D006861:Hydrogen Peroxide; D020928:Mitogen-Activated Protein Kinases