bZIP transcription factors PcYap1 and PcRsmA link oxidative stress response to secondary metabolism and development in Penicillium chrysogenum

Abstract

Background Reactive oxygen species (ROS) trigger different morphogenic processes in filamentous fungi and have been shown to play a role in the regulation of the biosynthesis of some secondary metabolites. Some bZIP transcription factors, such as Yap1, AtfA and AtfB, mediate resistance to oxidative stress and have a role in secondary metabolism regulation. In this work we aimed to get insight into the molecular basis of this regulation in the industrially important fungus Penicillium chrysogenum through the characterization of the role played by two effectors that mediate the oxidative stress response in development and secondary metabolism. Results In P. chrysogenum, penicillin biosynthesis and conidiation are stimulated by the addition of H2O2 to the culture medium, and this effect is mediated by the bZIP transcription factors PcYap1 and PcRsmA. Silencing of expression of both proteins by RNAi resulted in similar phenotypes, characterized by increased levels of ROS in the cell, reduced conidiation, higher sensitivity of conidia to H2O2 and a decrease in penicillin production. Both PcYap1 and PcRsmA are able to sense H2O2-generated ROS in vitro and change its conformation in response to this stimulus. PcYap1 and PcRsmA positively regulate the expression of brlA, the first gene of the conidiation central regulatory pathway. PcYap1 binds in vitro to a previously identified regulatory sequence in the promoter of the penicillin gene pcbAB: TTAGTAA, and to a TTACTAA sequence in the promoter of the brlA gene, whereas PcRsmA binds to the sequences TGAGACA and TTACGTAA (CRE motif) in the promoters of the pcbAB and penDE genes, respectively. Conclusions bZIP transcription factors PcYap1 and PcRsmA respond to the presence of H2O2-generated ROS and regulate oxidative stress response in the cell. Both proteins mediate ROS regulation of penicillin biosynthesis and conidiation by binding to specific regulatory elements in the promoters of key genes. PcYap1 is identified as the previously proposed transcription factor PTA1 (Penicillin Transcriptional Activator 1), which binds to the regulatory sequence TTAGTAA in the pcbAB gene promoter. This is the first report of a Yap1 protein directly regulating transcription of a secondary metabolism gene. A model describing the regulatory network mediated by PcYap1 and PcRsmA is proposed.

Promoter screening and identification for metabolic regulation in Acremonium chrysogenum

“…The ROS‐responsive transcriptional factors PcYap1 and PcRsmA interact with specific sequences on the promoter of the penicillin biosynthesis gene PcpcbAB , with the DNA‐Binding sites of PcYap1 and PcRsmA being TTAGTAA and TTAGACA, respectively. [ 34 ] The fermentation processes in both Penicillium chrysogenum and A. chrysogenum might have been regulated by ROS at transcriptional level. [ 44 ] The transcription regulatory factors yap1 and rsm2 may influence the transcription of crucial genes by interacting with specific promoter motifs, ultimately impacting CPC production.…”

“…[ 35 ] The transcription factors PcYap1 and PcRsmA responsive to ROS can bind to the specific sequence of PcpcbAB , thereby affecting penicillin biosynthesis. [ 34 ] The forkhead transcription factor AcFKH1 interacts with CPCR1, [ 35 ] and in the absence of Acfkh1 , the overexpression of cpcr1 no longer affects conidiospore production. [ 36 ] It is worth exploring the combination of homologous genes encoding these transcriptional factors with different promoters in A. chrysogenum , as this approach might have a significant impact on CPC biosynthesis and could serve as candidate genes for Golden Gate assembly.…”

“…The terminators used were T trpC and T A1 , and a total of 60 combinations were utilized. Among them, rsm1 , rsm2 , yap1 , and yap3 are transcription factors related to stress response in filamentous fungi, [ 34 ] and fkh1 is a global regulatory factor reported in A. chrysogenum . [ 35 ] The transcription factors PcYap1 and PcRsmA responsive to ROS can bind to the specific sequence of PcpcbAB , thereby affecting penicillin biosynthesis.…”

Ena Proteins Respond to PacC-Mediated pH Signaling Pathway and Play a Crucial Role in Patulin Biosynthesis

“…In addition, the expressions of several well-known regulators, AP1 , CreA , Sge1 , and Hog1 genes, were significantly downregulated in PeEnas deletion mutants compared to WT , while global Velvet complex transcription factors were not affected. In fungi, AP1-like bZIP factor AP1 regulates oxidative stress-responsive genes and is involved in secondary metabolism [ 36 , 37 ]. Hog1 functions in oxidative stress tolerance and is involved in trichothecene biosynthesis [ 38 , 39 ].…”

Genome-Wide Identification and Functional Analysis of the bZIP Transcription Factor Family in Rice Bakanae Disease Pathogen, Fusarium fujikuroi

“…In recent years, with the continuous improvement of genome databases, more and more TF families have been identified, such as bZIP [ 22 ], MYB [ 23 ], GATA [ 24 ], and PacC [ 25 ]. bZIP TFs are one of the most widely distributed and conserved proteins of eukaryotes.…”