ROS signal transduction and cell differentiation in filamentous fungi

Fernando Lara-Rojas, Olivia Sánchez, Jesús Aguirre

Author address: 

Instituto de Fisiologí­a Celular, Universidad Nacional Autónoma de México

Abstract: 

A phosphorelay system coupled to a MAP kinase module is involved in sensing and processing environmental signals in Fungi. In Aspergillus nidulans, response regulator (RR) SskA transmits oxidative stress signals to the stress MAPK (SAPK) SakA, which in turns physically interacts with ATF/CREB transcription factor AtfA in the nucleus. This defines a general stress8208;signalling pathway, which plays differential roles in oxidative stress responses during growth and development. AtfA is needed for the expression of several genes, the conidial accumulation of SakA and the viability of conidia. Furthermore, SakA is active (phosphorylated) in asexual spores, remaining phosphorylated in dormant conidia and becoming dephosphorylated during germination. SakA phosphorylation in spores depends on certain (SskA) but not other (SrrA and NikA) components of the phosphorelay system. Constitutive phosphorylation of SakA prevents both, germ tube formation and nuclear division. Similarly, Neurospora crassa SakA orthologue OS8208;2 is phosphorylated in intact conidia and gets dephosphorylated during germination. We propose that SAPK phosphorylation is a conserved mechanism to regulate transitions between non8208;growing (spore) and growing (mycelia) states. The Aspergilli contain a second SAPK called MpkC. Although mpkC mutants are not sensitive to oxidative or osmotic stress, they produce more spores that the wild type strain, suggesting that SakA and MpkC regulate processes related to the production and germination of spores. In addition, to the SakA pathway, RR SrrA and the AP8208;1 trancription factor NapA are differentially involved in ROS signalling and cell differentiation.  Â 
2012

abstract No: 

PS6.1

Full conference title: 

11 th European Conference on Fungal Genetics
    • ECFG 11th (2012)