OS-4 — Aspergillus fumigatus

Summary

AFU1G10940 (symbol OS-4, preferred name AfOS-4) on chromosome 1 of Aspergillus fumigatus encodes a MAP kinase kinase kinase (MAPKKK) of the Ssk2/Ssk22 family, possessing protein serine/threonine kinase activity and MEKK activity (EC 2.7.11.-). The gene is associated with multiple MAPK cascades, including stress-activated, p38, JNK, cell integrity, and pheromone response pathways, as well as calcium signaling, conidia and spore formation, morphogenesis, cell division, contractile ring assembly, and fungal-type cell wall organization. It localizes to the Mcs4 RR-MAPKKK complex, division septum, cell tip, division site, plasmalemma, cytoplasm, and cytosol. AfOS-4 is linked to invasive pulmonary aspergillosis and has been connected to numerous phenotypes including absent osmotic stress resistance, decreased cell cycle progression, abnormal bipolar budding, absent innate thermotolerance, and sterile mating. Studies of related genes in other species link the family to virulence modulation and oxidative stress responses.