The SEB-1 Transcription Factor Binds to the STRE Motif in Neurospora crassa and Regulates a Variety of Cellular Processes Including the Stress Response and Reserve Carbohydrate Metabolism

Abstract

When exposed to stress conditions, all cells induce mechanisms resulting in an attempt to adapt to stress that involve proteins which, once activated, trigger cell responses by modulating specific signaling pathways. In this work, using a combination of pulldown assays and mass spectrometry analyses, we identified the Neurospora crassa SEB-1 transcription factor that binds to the Stress Response Element (STRE) under heat stress. Orthologs of SEB-1 have been functionally characterized in a few filamentous fungi as being involved in stress responses; however, the molecular mechanisms mediated by this transcription factor may not be conserved. Here, we provide evidences for the involvement of N. crassa SEB-1 in multiple cellular processes, including response to heat, as well as osmotic and oxidative stress. The Δseb-1 strain displayed reduced growth under these conditions, and genes encoding stress-responsive proteins were differentially regulated in the Δseb-1 strain grown under the same conditions. In addition, the SEB-1-GFP protein translocated from the cytosol to the nucleus under heat, osmotic, and oxidative stress conditions. SEB-1 also regulates the metabolism of the reserve carbohydrates glycogen and trehalose under heat stress, suggesting an interconnection between metabolism control and this environmental condition. We demonstrated that SEB-1 binds in vivo to the promoters of genes encoding glycogen metabolism enzymes and regulates their expression. A genome-wide transcriptional profile of the Δseb-1 strain under heat stress was determined by RNA-seq, and a broad range of cellular processes was identified that suggests a role for SEB-1 as a protein interconnecting these mechanisms.

Chitin and chitosan remodeling defines vegetative development and Trichoderma biocontrol

“…Strong response to ROS and mycoparasitism related stresses coincided with a higher enrichment of such elements. Interestingly, among the binding motives that were found highly enriched was also the Msn2/Msn4 homologous AGGGG-binding element that is recognized in T. atroviride and N. crassa by the transcription factor Seb1 [81,103] and is related to HOGstress and nutrient availability. Moreover, a highly conserved enrichment of the TEC1 binding motif in the promoters of chs5 and chs7 was identified.…”

Functional diversity in the pH signaling pathway: an overview of the pathway regulation in Neurospora crassa

“…We demonstrated, in N. crassa, that glycogen and/or trehalose metabolism is regulated by the CRE-1 (Cupertino et al 2015), PAC-3 (Cupertino et al 2012) and SEB-1 (Freitas et al 2016) transcription factors. In addition, we described that the CRZ-1 transcription factor cooperates with PAC-3 to regulate the metabolism of both these carbohydrates under pH stress (Virgilio et al 2017).…”

“…The production of cellulolytic and xylanolytic enzymes is regulated by glucose through the action of the CreA (A. nidulans), CRE-1 (N. crassa) or CRE1 (T. reesei) transcription factors. An in silico analysis of the pac-3 promoter revealed the existence of numerous putative DNA binding sites for transcription factors including the PAC-3 site itself (5′-BGCCVAGV-3′), the CRZ-1 (5′-RDGGCKNWR-3′) (Weirauch et al 2014), the CRE-1 (5′-SYGGRG-3′) (Sun and Glass 2011;Cupertino et al 2015), and the SEB-1 (5′-CCCCT-3′) sites (Freitas et al 2016) (Fig. 1a).…”

Neurospora crassa developmental control mediated by the FLB-3 transcription factor

“…Briefly, 10 8 conidia from the flb-3 þ strain were grown in different flasks containing 125 ml of VM liquid medium with 2 % sucrose, pH 5.8, and incubated at 30 C and 200 rpm during 12, 24, 48 and 60 h. Samples were fixed by adding formaldehyde (Sigma) to a final concentration of 1 %, and the formaldehyde was quenched with glycine. Samples were suspended in ChIP lysis buffer and the procedure followed the conditions previously described (Freitas et al, 2016). The DNA was quantified using Nanovue Plus (GE Healthcare) and 200 ng of Input DNA (IN), no Ab (N, reaction without antibody) and IP [immunoprecipitated DNAs with anti-GFP antibody (Sigma)] samples were amplified by PCR using primers specific for each promoter (Table S1, ChIP-PCR).…”