bZIP transcription factors affecting secondary metabolism, sexual development and stress responses in Aspergillus nidulans

Abstract

The eukaryotic basic leucine zipper (bZIP) transcription factors play critical roles in the organismal response to the environment. Recently, a novel YAP-like bZIP, restorer of secondary metabolism A (RsmA), was found in a suppressor screen of an Aspergillus nidulans secondary metabolism (SM) mutant in which overexpression of rsmA was found to partially remediate loss of SM in Velvet Complex mutants. The Velvet Complex is a conserved fungal transcriptional heteromer that couples SM with sexual development in fungi. Here we characterized and contrasted SM in mutants of RsmA and four other A. nidulans bZIP proteins (NapA, ZipA, ZipB and ZipC) with predicted DNA binding motifs similar to RsmA. Only two overexpression mutants exhibited both SM and sexual abnormalities that were noteworthy: OE : : rsmA resulted in a 100-fold increase in sterigmatocystin and a near loss of meiotic spore production. OE : : napA displayed decreased production of sterigmatocystin, emericellin, asperthecin, shamixanthone and epishamixanthone, coupled with a shift from sexual to asexual development. Quantification of bZIP homodimer and heterodimer formation using fluorescence resonance energy transfer (FRET) suggested that these proteins preferentially self-associate.

bZIP Transcription Factors in the Oomycete Phytophthora infestans with Novel DNA-Binding Domains Are Involved in Defense against Oxidative Stress

“…Genes regulated by fungal bZIPs that help detoxify the cell include catalases, peroxidases, oxidoreductases, and glutathione synthases (20,21,65,66). Genome-wide expression analysis of the P. infestans strains with silenced bZIPs will help understand the mechanisms that govern oxidative stress response in P. infestans.…”

Basic Leucine Zipper (bZIP) Domain Transcription Factor MBZ1 Regulates Cell Wall Integrity, Spore Adherence, and Virulence in Metarhizium robertsii

“…Different bZIP-type TFs have also been characterized in various filamentous fungal species, including Aspergillus nidulans (7,8), Neurospora crassa (9), and the plant pathogens Fusarium graminearum (10 -12) and Magnaporthe oryzae (13)(14)(15). Deletions and functional characterizations of these genes revealed that bZIP-type TFs are involved in mediating fungal development, sexuality, stress responses, secondary metabolisms, and especially the virulence of plant pathogens.…”

Further characterization of the role of the mitochondrial high-mobility group box protein in the intracellular redox environment of Aspergillus nidulans

“…In A. nidulans, the stress response proteins NapA and DlpA have been shown to play a role in developmental processes and sterigmatocystin production (Wartenberg et al, 2012;Yin et al, 2013). In this work, we outlined the importance of HmbB -a protein that seriously affects vegetative and sexual spore viability and sterigmatocystin production (Karácsony et al, 2014) -in maintaining the cellular redox environment.…”

“…An intriguing relation between oxidative stress, secondary metabolite production and sexual development has been unfolding during the last few years in Aspergillus, which was initiated by the work of Reverberi et al (2007) on Aspergillus parasiticus and Aspergillus ochraceus, and further studied by many others (Baidya et al, 2014;Grintzalis et al, 2014;Reverberi et al, 2012;Wartenberg et al, 2012;Yin et al, 2013). In A. nidulans, the stress response proteins NapA and DlpA have been shown to play a role in developmental processes and sterigmatocystin production (Wartenberg et al, 2012;Yin et al, 2013).…”