Project description:The DOM-A complex regulates cell growth and proliferation in Drosophila. Analogous to the mammalian Tip60–p400 complex, DOM-A integrates two epigenetic effectors: a SWR1-type ATPase (Domino-A) that mediates histone exchange and the Tip60/KAT5 acetyltransferase. We identified Xbp1, a conserved transcriptional regulator of the unfolded protein response (UPR), as a tight interactor of the immunopurified DOM-A complex and explored the functional consequences of this association. Integrative analysis of Xbp1 and DOM-A occupancy in proliferating cells, together with reciprocal protein depletion, revealed two distinct modes of Xbp1 chromatin binding. In a sequence-specific mode, Xbp1 recruits DOM-A to motif-bearing promoters of UPR genes. In a second, motif-independent mode, Xbp1 localizes to hundreds of high-confidence DOM-A binding sites that lack Xbp1 recognition motifs; these interactions depend on DOM-A, consistent with a “reverse targeting” mechanism. Consistent with functional coupling, depletion of DOM-A reduces Xbp1 protein abundance without affecting Xbp1 mRNA levels, suggesting post-translational stabilization of Xbp1 upon association with DOM-A. Together, these findings indicate that the genome-wide interplay between Xbp1 and DOM-A may integrate UPR signaling with the broader, DOM-mediated regulation of cell growth and proliferation.
Project description:Diazotrophs provide the main source of reactive nitrogen to the ocean, sustaining primary productivity and CO2 uptake. Climate change is raising temperatures, decreasing pH and reducing nutrient availability. How microbes respond to these changes is largely unexplained. Similarly, the role of DOM in the growth and survival of certain diazotrophic organisms is poorly understood. Moreover, growing evidence indicates some diazotrophs are capable of utilizing distinct DOM compounds via osmotrophy providing them with additional metabolic plasticity and ecological advantages compared to other non-diazotrophic microbes. We aimed to understand how osmotrophy could modify carbon uptake and alleviate energy stress in diazotrophs under ongoing climate change perturbations. We hypothesized that Crocosphaera preferentially uses DOM when labile as a carbon source in present pH conditions, as compared to future more acidic scenarios with higher access to inorganic carbon. Alternatively, the lower pH may cause Crocosphaera to be energy limited when trying to maintain intracellular homeostasis which would favour DOM uptake as an extra source of energy.
Project description:Transcriptome response of the yeasts C. glabrata and S. cerevisiae treated by an antifungal agent, benomyl Keywords: time course; stress response
Project description:Xylanolytic enzyme systems in ascomycetous yeasts remain underexplored, despite the presence of yeasts in various xylan-rich ecological niches. In this study, we investigated the secreted xylanolytic machineries of three Blastobotrys species—B. mokoenaii, B. illinoisensis, and B. malaysiensis—by integrating genome annotation, bioinformatics, and secretome analyses of cultures grown on beechwood glucuronoxylan. Our findings demonstrate that these yeasts effectively hydrolyze xylan through the secretion of xylanases from the glycoside hydrolase (GH) family 11, which play a central role in cleaving the xylan backbone. Additionally, the yeasts produce a diverse array of other CAZymes, including members of GH families 3, 5, 30_7, and 67, with putative roles in xylan degradation. We also report on the heterologous expression and functional characterization of the GH30_7 xylanase BmXyn30A from B. mokoenaii, which exhibits both glucoronoxylanase and xylobiohydrolase activities. Distinct differences were observed in the xylooligosaccharide profiles generated by BmXyn30A compared to the previously characterized GH11 xylanase BmXyn11A. Furthermore, we demonstrate the synergistic effects between BmXyn30A and BmXyn11A during the hydrolysis of beechwood glucuronoxylan, where the enzymes exhibited complementary roles that enhanced the deconstruction of this complex hemicellulose substrate. These findings broaden our understanding of the xylanolytic systems in yeasts and underscore the potential of Blastobotrys species as cell factories and natural xylanase producers. The enzymes they produce hold promise for biorefining applications, enabling efficient utilization of renewable, xylan-rich plant biomass resources.