Project description:The yeast-filament transition is essential for the virulence of a variety of fungi that are pathogenic to humans. N-acetylglucosamine (GlcNAc), a ubiquitous molecule in both the environment and host, is one of the most potent inducers of filamentation in Candida albicans and thermally dimorphic fungi such as Histoplasma capsulatum and Blastomyces dermatitidis. However, GlcNAc suppresses rather than promotes filamentation in Candida tropicalis, a fungal species that is closely related to C. albicans. Furthermore, we discover that glucose induces filamentous growth in C. tropicalis. Mutation and overexpression assays demonstrate that the conserved cAMP signaling pathway plays a central role in the regulation of filamentation in C. tropicalis. Activation of this pathway promotes filamentation in C. tropicalis, while inactivation of this pathway results in a serious growth defect in filamentation. By screening an overexpression library of 154 transcription factors, we have identified approximately 40 regulators of filamentous growth in C. tropicalis. Although most of the regulators (e.g., Tec1, Gat2, Nrg1, Sfl1, Sfl2, and Ash1) demonstrate a conserved role in the regulation of filamentation, similar to their homologs in C. albicans or S. cerevisiae, some of them are specific to C. tropicalis. For example, Czf1 and Efh1 repress filamentation, while Wor1, Zcf3, and Hcm1 promote filamentation in C. tropicalis. Bcr1, Aaf1, and Csr1 play a specific role in the process of GlcNAc-regulated filamentation. Our findings indicate that multiple interconnected signaling pathways are involved in the regulation of filamentation in C. tropicalis. These mechanisms have conserved and divergent features among different Candida species. Total RNA profiles of cells grown in Lee's glucose or Lee's GlcNAc medium.
Project description:The yeast-filament transition is essential for the virulence of a variety of fungi that are pathogenic to humans. N-acetylglucosamine (GlcNAc), a ubiquitous molecule in both the environment and host, is one of the most potent inducers of filamentation in Candida albicans and thermally dimorphic fungi such as Histoplasma capsulatum and Blastomyces dermatitidis. However, GlcNAc suppresses rather than promotes filamentation in Candida tropicalis, a fungal species that is closely related to C. albicans. Furthermore, we discover that glucose induces filamentous growth in C. tropicalis. Mutation and overexpression assays demonstrate that the conserved cAMP signaling pathway plays a central role in the regulation of filamentation in C. tropicalis. Activation of this pathway promotes filamentation in C. tropicalis, while inactivation of this pathway results in a serious growth defect in filamentation. By screening an overexpression library of 154 transcription factors, we have identified approximately 40 regulators of filamentous growth in C. tropicalis. Although most of the regulators (e.g., Tec1, Gat2, Nrg1, Sfl1, Sfl2, and Ash1) demonstrate a conserved role in the regulation of filamentation, similar to their homologs in C. albicans or S. cerevisiae, some of them are specific to C. tropicalis. For example, Czf1 and Efh1 repress filamentation, while Wor1, Zcf3, and Hcm1 promote filamentation in C. tropicalis. Bcr1, Aaf1, and Csr1 play a specific role in the process of GlcNAc-regulated filamentation. Our findings indicate that multiple interconnected signaling pathways are involved in the regulation of filamentation in C. tropicalis. These mechanisms have conserved and divergent features among different Candida species.
Project description:In filamentous fungi, arginine methylation has been implicated in morphogenesis, mycotoxin biosynthesis, pathogenicity, and stress response although the exact role of this posttranslational modification in these processes remains obscure. Here, we present the first genome-wide transcriptome analysis in filamentous fungi that compared expression levels of genes regulated by type I and type II protein arginine methyltransferases (PRMTs).
Project description:Chromatin complexes control a vast number of epigenetic developmental processes. Filamentous fungi present an important clade of microbes with poor understanding of underlying epigenetic mechanisms. Here, we describe a chromatin binding complex in the fungus Aspergillus nidulans composing of a H3K4 histone demethylase KdmB, a cohesin acetyltransferase (EcoA), a histone deacetylase (RpdA) and a histone reader/E3 ligase protein (SntB). In vitro and in vivo evidence demonstrate that this KERS complex is assembled from the EcoA-KdmB and SntB-RpdA heterodimers. KdmB and SntB play opposing roles in regulating the cellular levels and stability of EcoA, as KdmB prevents SntB-mediated degradation of EcoA. The KERS complex is recruited to transcription initiation start sites at active core promoters exerting promoter-specific transcriptional effects. Interestingly, deletion of any one of the KERS subunits results in a common negative effect on morphogenesis and production of secondary metabolites, molecules important for niche securement in filamentous fungi. Consequently, the entire mycotoxin sterigmatocystin gene cluster is downregulated and asexual development is reduced in the four KERS mutants. The elucidation of the recruitment of epigenetic regulators to chromatin via the KERS complex provides the first mechanistic, chromatin-based understanding of how development is connected with small molecule synthesis in fungi.
Project description:Copper (Cu) homeostasis has not been well-documented in filamentous fungi, especially extremophiles. Acidophilic fungus Acidomyces richmondensis MEY-1 has extremely high Cu tolerance among filamentous fungi, and the transcription factor ArAceA has been shown to be involved in this process. The ArAceA deletion mutant (ΔArAceA) exhibits specific growth defects at Cu concentrations of ≥ 10 mM. To gain genomic insight into the Cu tolerance mechanism and the role of ArAceA in Cu tolerance, we treated the ΔArAceA mutant and WT strains with or without 15 mM CuCl2 for 6 h. Transcriptional profiling analysis revealed that ΔArAceA mutant is transcriptionally more sensitive to Cu than the wild-type strain. Our findings provide insights into the molecular basis of Cu tolerance in acidophilic filamentous fungi.
Project description:The ability to grow at host temperature is a critical trait for most pathogenic microbes of humans. Thermally dimorphic fungal pathogens, including Histoplasma capsulatum, are a class of soil fungi that undergo a dramatic change in cell shape and virulence gene expression in response to host temperature. Here we elucidate a complex temperature-responsive network in H. capsulatum, which switches from an environmental filamentous form to a pathogenic yeast form. We dissect the circuit driven by three regulators that control yeast-phase growth, and demonstrate that these factors, including two deeply conserved Velvet family proteins of unknown function, associate with DNA. We identify and characterize a fourth regulator of this pathway, and define cis-acting motifs that recruit these transcription factors to a tightly interwoven network of temperature-responsive target genes. Our results provide the first comprehensive analysis of the complex transcriptional network that links temperature to morphology and virulence in thermally dimorphic fungi. This submission gives the chromatin immunoprecipitation results.
Project description:The ability to grow at host temperature is a critical trait for most pathogenic microbes of humans. Thermally dimorphic fungal pathogens, including Histoplasma capsulatum, are a class of soil fungi that undergo a dramatic change in cell shape and virulence gene expression in response to host temperature. Here we elucidate a complex temperature-responsive network in H. capsulatum, which switches from an environmental filamentous form to a pathogenic yeast form. We dissect the circuit driven by three regulators that control yeast-phase growth, and demonstrate that these factors, including two deeply conserved Velvet family proteins of unknown function, associate with DNA. We identify and characterize a fourth regulator of this pathway, and define cis-acting motifs that recruit these transcription factors to a tightly interwoven network of temperature-responsive target genes. Our results provide the first comprehensive analysis of the complex transcriptional network that links temperature to morphology and virulence in thermally dimorphic fungi. This submission gives the chromatin immunoprecipitation results. For each of the four Ryp proteins, ChIP vs. input hybridizations were performed for three replicate immunoprecipitations from the wild-type strain and two negative control replicates from the corresponding mutant strain.