Biology subjects

de Vroet, T.

Publications and source records attributed to de Vroet, T..

2 recordsLinked to original sources

bioRxiv2026

The transcription factor Ste12(1) from Nakaseomyces glabratus acts pheromone-responsive in S. cerevisiae but seems decoupled from its cognate upstream GPCR in its native host.

G-protein-coupled receptor (GPCR)-mediated signalling pathways govern critical cellular responses in fungi, including mating, biofilm formation, and virulence. The mating pathway of Saccharomyces cerevisiae, in which peptide-sensing GPCRs (peptide GPCRs) activate a MAP kinase cascade and the transcription factor Ste12, has thereby served as the canonical model for fungal peptide GPCR signalling. Homologues of this pathway are conserved across many fungi, including the high-priority pathogen Nakaseomyces glabratus. Yet the function of this pathway in this mating-incompetent pathogen remains unclear. Here, we investigated whether the central transcription factor Ste12 of N. glabratus (NgSte12(1)) can act as a peptide GPCR-coupled transcription factor using a component-swapping strategy in which pathway elements from N. glabratus and S. cerevisiae were reciprocally exchanged and assessed using fluorescent and growth arrest readouts. We show that NgSte12(1) is in principle capable of supporting peptide-GPCR-dependent activation in S. cerevisiae, however, subtle and dependent on promoter identity. Ste12 chimaeras further demonstrate that all three NgSte12(1) subdomains are individually functional and compatible with their S. cerevisiae counterparts. Heterologous expression of ScSte12 in N. glabratus shows constitutive pathway activation, while NgSte12(1) does not show pathway activation in N. glabratus. Peptide-GPCR expression experiments indicate a block in N. glabratus signalling upstream of Ste12 (1): the S. cerevisiae peptide-GPCR Ste2 (ScSte2) activated the N. glabratus Ste12 GPCR-dependent downstream signalling constitutively, while NgSte2 failed to activate signalling in its native environment. Together, these results indicate that NgSte12(1) is a competent pheromone-responsive transcription factor that can couple to a heterologous GPCR in a heterologous context but is unresponsive to its own cognate upstream peptide/GPCR pair, either because it binds a yet unknown ligand or the signalling is rewired in this pathogen.

microbiology↗

bioRxiv2022

Genome-scale metabolic modelling enables deciphering ethanol metabolism via the acrylate pathway in the propionate-producer Anaerotignum neopropionicum

BackgroundMicrobial production of propionate from diluted streams of ethanol (e.g., deriving from syngas fermentation) is a sustainable alternative to the petrochemical production route. Yet, few ethanol-fermenting propionigenic bacteria are known, and understanding of their metabolism is limited. Anaerotignum neopropionicum is a propionate-producing bacterium that uses the acrylate pathway to ferment ethanol and CO2 to propionate and acetate. In this work, we used computational and experimental methods to study the metabolism of A. neopropionicum and, in particular, the pathway for conversion of ethanol into propionate. ResultsOur work describes iANEO_SB607, the first genome-scale metabolic model (GEM) of A. neopropionicum. The model was built combining the use of automatic tools with an extensive manual curation process, and it was validated with experimental data from this and published studies. The model predicted growth of A. neopropionicum on ethanol, lactate, sugars and amino acids, matching observed phenotypes. In addition, the model was used to implement a dynamic flux balance analysis (dFBA) approach that accurately predicted the fermentation profile of A. neopropionicum during batch growth on ethanol. A systematic analysis of the metabolism of A. neopropionicum combined with model simulations shed light into the mechanism of ethanol fermentation via the acrylate pathway, and revealed the presence of the electron-transferring complexes NADH-dependent reduced ferredoxin:NADP+ oxidoreductase (Nfn) and acryloyl-CoA reductase-EtfAB, identified for the first time in this bacterium. ConclusionsThe realisation of the GEM iANEO_SB607 is a stepping stone towards the understanding of the metabolism of the propionate-producer A. neopropionicum. With it, we have gained insight into the functioning of the acrylate pathway and energetic aspects of the cell, with focus on the fermentation of ethanol. Overall, this study provides a basis to further exploit the potential of propionigenic bacteria as microbial cell factories.

systems biology↗