Alistair Jp Brown

University of Exeter | UoE

Microbes rarely exist in isolation, rather, they form intricate multi-species communities that colonise our bodies and inserted medical devices. However, the efficacy of antimicrobials is measured in clinical laboratories exclusively using microbial monocultures. Here, to determine how multi-species interactions mediate selection for resistance dur...

Phagocytosis is an essential component of our immune defence against fungal pathogens. Differences in the dynamics of phagocyte migration, recognition, uptake and phagolysosome maturation are dependent on the characteristics of the fungal cargo, and in particular to differences in cell wall composition and cellular morphology. However, studies that...

Sporothrix brasiliensis is an emerging fungal pathogen frequently associated with zoonotic transmission of sporotrichosis. Although certain virulence factors have been proposed as potential sporotrichosis determinants, the scarcity of molecular tools for reverse genetics studies on Sporothrix has significantly impeded the dissection of mechanisms u...

The immunogenicity of Candida albicans cells is influenced by changes in the exposure of microbe-associated molecular patterns (MAMPs) on the fungal cell surface. Previously, the degree of exposure on the C. albicans cell surface of the immunoinflammatory MAMP β-(1,3)-glucan was shown to correlate inversely with colonisation levels in the gastroint...

Candida albicans exists as a commensal of mucosal surfaces and the gastrointestinal tract without causing pathology. However, this fungus is also a common cause of mucosal and systemic infections when antifungal immune defenses become compromised. The activation of antifungal host defenses depends on the recognition of fungal pathogen-associated mo...

The human gut microbiota protects the host from invading pathogens and the overgrowth of indigenous opportunistic species via a process called colonisation resistance. Here, we investigated the antagonistic activity of human gut bacteria towards Candida albicans, an opportunistic fungal pathogen that can cause severe infections in susceptible indiv...

Aspergillus fumigatus is the leading cause of the fungal invasive disease called aspergillosis, which is associated with a high mortality rate that can reach 50% in some groups of immunocompromised individuals. The increasing prevalence of azole-resistant A. fumigatus isolates, both in clinical settings and the environment, highlights the importanc...

In certain niches, microbes encounter environmental challenges that are temporally linked. In such cases, microbial fitness is enhanced by the evolution of anticipatory responses where the initial challenge simultaneously activates pre-emptive protection against the second impending challenge. The accumulation of anticipatory responses in domestica...

Reactive Oxygen Species (ROS) are highly reactive molecules that can induce oxidative stress. For instance, the oxidative burst of immune cells is well known for its ability to inhibit the growth of invading pathogens. However, ROS also mediate redox signalling, which is important for the regulation of antimicrobial immunity. Here, we report a cruc...

Candida auris is among the most important emerging fungal pathogens, yet mechanistic insights into its immune recognition and control are lacking. Here, we integrate transcriptional and functional immune-cell profiling to uncover innate defence mech- anisms against C. auris. C. auris induces a specific transcriptome in human mononuclear cells, a st...

Despite the importance of fungal cell walls as the principle determinant of fungal morphology and the defining element determining fungal interactions with other cells, few scalar models have been developed that reconcile chemical and microscopic attributes of its structure. The cell wall of the fungal pathogen Candida albicans is comprised of an a...

The immune system plays a critical role in protecting us against potentially fatal fungal infections. However, some fungal pathogens have evolved evasion strategies that reduce the efficacy of our immune defenses. Previously, we reported that the fungal pathogen Candida albicans exploits specific host-derived signals (such as lactate and hypoxia) t...

The human gut microbiota enhances the host’s resistance to enteric pathogens via colonisation resistance, a phenomenon that is driven by multiple mechanisms, such as production of antimicrobial metabolites and activation of host immune responses. However, there is limited information on how individual gut bacterial species, particularly many of the...

We designed experiments to assess whether fungal cell wall mannans function as an immune shield or an immune agonist. Fungal cell wall β-(1,3)-glucan normally plays a major and dominant role in immune activation. The outer mannan layer has been variously described as an immune shield, because it has the potential to mask the underlying β-(1,3)-gluc...

Candida albicans is a normal member of the human microbiome. It is also an opportunistic pathogen, which can cause life-threatening systemic infections in severely immunocompromized individuals. Despite the availability of antifungal drugs, mortality rates of systemic infections are high and new drugs are needed to overcome therapeutic challenges i...

Candida glabrata is an important human fungal pathogen known to trigger serious infections in immune-compromised individuals. Its ability to form biofilms, which exhibit high tolerance to antifungal treatments, has been considered as an important virulence factor. However, the mechanisms involving antifungal resistance in biofilms and the impact of...

The model yeasts, Saccharomyces cerevisiae and Schizosaccharomyces pombe, display Core Environmental Responses (CERs) that include the induction of a core set of stress genes in response to diverse environmental stresses. CERs underlie the phenomenon of stress cross-protection, whereby exposure to one type of stress can provide protection against s...

The fungal cell wall is an essential organelle that maintains cellular morphology and protects the fungus from environmental insults. For fungal pathogens such as Candida albicans, it provides a degree of protection against attack by host immune defences. However, the cell wall also presents key epitopes that trigger host immunity and attractive ta...

To colonise their host, pathogens must counter local environmental and immunological challenges. Here, we reveal that the fungal pathogen Candida albicans exploits diverse host-associated signals to promote immune evasion by masking of a major pathogen-associated molecular pattern (PAMP), β-glucan. Certain nutrients, stresses and antifungal drugs t...

In human hosts, the opportunistic fungal pathogen Candida albicans primarily proliferates in nutrient diverse niches. Environmental condition sensing regulates several fungal cellular features including, but not limited to, metabolism, cell wall elasticity, and virulence. In addition, yeast cell division exposes pathogen-associated molecular patter...

Animal, plant, and fungal cells occupy environments that impose changes in oxygen tension. Consequently, many species have evolved mechanisms that permit robust adaptation to these changes. The fungal pathogen Candida albicans can colonize hypoxic (low oxygen) niches in its human host, such as the lower gastrointestinal tract and inflamed tissues,...

In the version of this Article originally published, the following sentence was missing from the Acknowledgements: "R.E.B. is an EPSRC Healthcare Technologies Impact Fellow EP/N033671/1; I.G. is funded by ERC Consolidator grant 647292 MathModExp; A.J.P.B., N.A.R.G. and A.T. were funded by BBSRC grant BB/F00513X/1; K.H., I.G., S.N. and E.C. were fun...

Microbes rarely exist in isolation, rather, they form intricate multi-species communities that colonize our bodies and inserted medical devices. However, the efficacy of antimicrobials is measured in clinical laboratories exclusively using microbial monocultures. Here, to determine how multi-species interactions mediate selection for resistance dur...

In all eukaryotic kingdoms, mitogen-activated protein kinases (MAPKs) play critical roles in cellular responses to environmental cues. These MAPKs are activated by phosphorylation at highly conserved threonine and tyrosine residues in response to specific inputs, leading to their accumulation in the nucleus and the activation of their downstream ta...

Stress-activated protein kinase (SAPK) pathways are evolutionarily conserved eukaryotic signalling modules that are essential for the virulence of human pathogenic fungi. The Hog1 SAPK in Candida albicans is robustly phosphorylated in response to a number of host-imposed stresses, and is essential for virulence. The current dogma is that stress-ind...

The pathogenicity of the clinically important yeast, Candida albicans, is dependent on robust responses to host-imposed stresses. These stress responses have generally been dissected in vitro at 30°C on artificial growth media that do not mimic host niches. Yet host inputs, such as changes in carbon source or temperature, are known to affect C. alb...

The pathogenic yeast Candida albicans faces multiple challenges within its human host. These include the need to protect itself against the toxic oxidants used by the host to kill invading microbes, and the need to scavenge iron, an essential micronutrient that is limiting in certain tissues. The iron-containing enzyme, catalase, detoxifies hydroge...

Stress resistance of C. albicans tetON-CAT1 and ACT1-CAT1 strains. C. albicans cultures were pre-grown in YPD with 20 μM doxycycline, dilutions spotted onto YPD plates containing H2O2 and/or NaCl stresses at the specified concentrations, and photographed after 24 h growth at 30°C: CAT1/CAT1, Ca674; CAT1/cat1Δ, Ca1862; cat1Δ/cat1Δ, Ca1864; ACT1p-CAT...

Gating strategy for the analysis of C. albicans Cat1-GFP expressing cells. Exponential populations of C. albicans CAT1-GFP cells (Ca2213: S1 Table) growing in YPD at 30°C were subjected to fluorescence activated cell sorting. (A) First, singlets were selected and doublets excluded by analysing the FSC signals height versus area. (B) Next, cells of...

Iron suppresses the fitness defect of doxycycline-treated tetON-CAT1 C. albicans cells. (A) Iron supplementation restores the growth of doxycycline-treated tetON-CAT1 C. albicans cells to normal, while reducing the growth of wild type and cat1Δ null cells. The growth of new C. albicans isolates was monitored (OD600) in YPD containing 0 or 20 μM dox...

Strains used in this study. (PDF)

Analysis of C. albicans ACT1-GFP expressing cells. Exponential C. albicans ACT1-GFP cells (Ca230: S1 Table) were grown in the same way as for S2 Fig, and then subjected to fluorescence activated cell sorting, as before. (A) Singlets were selected and doublets excluded by analysing the FSC signals height versus area. (B) Cells of similar size were t...

Loss of phenotype in some tetON-CAT1 isolates. TetON-CAT1 isolates 1, 4 and 10 (Ca2038, Ca2041, Ca2044: S1 Table) behaved differently in vivo: isolate 1 displayed decreased colonisation in certain tissues (Fig 5), whereas isolates 4 and 10 did not (see text). Therefore, we tested whether isolates 4 and 10 had lost their phenotype over time. To achi...

Primers used in this study. (PDF)

Barcodes used in this study. (PDF)

The Ypd1 phosphorelay protein is a central constituent of fungal two-component signal transduction pathways. Inhibition of Ypd1 in Saccharomyces cerevisiae and Cryptococcus neoformans is lethal due to the sustained activation of the 'p38-related' Hog1 stress-activated protein kinase (SAPK). As two-component signalling proteins are not found in anim...

Effect of deleting Hog1, or Hog1 and Ypd1, on experimental infection outcome. Infection with either hog1Δ or hog1Δ ypd1Δ cells resulted in weight increases, lower kidney fungal burdens and, thus, lower outcome scores compared to that observed with wild-type cells. Statistical analysis revealed that for all parameters; weight loss, kidney fungal bur...

Oligonucleotides used in this study. (DOCX)

Doxycycline does not stimulate Hog1 phosphorylation. The indicated strains were treated or not with 20μg/ml doxycycline (DOX) for 1 h, and cell extracts were analysed for phosphorylated Hog1 by western blotting. Blots were probed for phosphorylated Hog1 (Hog1-P), stripped and reprobed for total Hog1 (Hog1). Hog1 phosphorylation is stimulated upon d...

Doxycycline treatment does not affect rate of uptake of C. albicans tetO-YPD1 cells. (A) Percentage uptake of tetOYPD1 cells grown in the presence (+DOX) or absence (-DOX) of doxycycline. No significant difference between uptake events + or − minus Dox by J774.1 macrophages after 6h co incubation was detected. (B) Engulfment time required for the i...

HOG1 is regulated differently at the RPS10 locus in response to sustained Hog1 activation. (A) Hog1 phosphorylation is not sustained in hog1Δypd1Δ+HOG1 cells over time and this is accompanied by a reduction in total Hog1 protein levels. Western blot analysis of whole cell extracts isolated from exponentially growing hog1Δ+HOG1 (JC52) and hog1Δypd1Δ...

Doxycycline treatment does not affect C. albicans virulence in a murine infection model. Kidney fungal burden measurements, percentage weight loss, and outcome score measurements of mice infected with wild-type C. albicans cells (SC5314) and administered doxycycline (+DOX) or not (-DOX). Comparison of +DOX and -DOX treated groups by Kruskal-Wallis...

Doxycycline treatment does not affect C. albicans virulence in a C. elegans model of infection. Nematodes were infected with wild-type THE1 or wild-type JC806 cells and transferred to liquid medium either with (+DOX) or without (-DOX) doxycycline. Doxycycline had no significant impact on nematode killing infected with either wild-type strain in (P>...

As they proliferate, fungi expose antigens at their cell surface that are potent stimulators of the innate immune response, and yet the commensal fungus Candida albicans is able to colonize immuno competent individuals. We show that C. albicans may evade immune detection by presenting a moving immunological target. We report that the exposure of β-...

Candida glabrata is considered a major opportunistic fungal pathogen of humans and has emerged as a leading cause of nosocomial fungal infections. The capacity of this yeast species to cause infections is dependent on the ability to grow within the human host environment and to assimilate the carbon sources available. Previous studies have suggeste...

Candida spp. often inhabit niches that are glucose-limited but rich in alternative carbon sources, such as lactate or acetate, an ability that contributes to cells’ virulence. In glucose-poor niches, Candida albicans cells express JEN1 and JEN2 genes encoding the carboxylic acids transporters Jen1 and Jen2, respectively, which have been reported to...

Subcellular localisation of splenic copper trans-Golgi transporting ATPase ATP7B is unchanged during C. albicans infection. As the infection progresses, ATP7B protein decreases in the red pulp of the spleen, as determined by immunoflourescent probing with Alexa Fluor 674 labelled antibodies. The subcellular localisation of the protein does not chan...

C. albicans CRP1 copper efflux gene and CTR1 copper importer gene are conversely regulated with changing copper concentrations. Fungal cells were incubated at 30°C for 1h in YPD supplemented with increasing concentrations of CuSO4. The relative transcript abundances are normalised to ACT1. The values are averages of duplicate measurements performed...

The effect of copper and iron chelation on the expression of C. albicans genes encoding core metabolism and metal homeostatic functions. Early exponential phase C. albicans SC5314 cells grown at 30°C in YNB-Glucose medium were exposed to 170 μM iron chelator BPS or 250 μM copper chelator BCS for 30 min, before fixing in RNAlater. Gene expression wa...

During development of systemic candidiasis, renal superoxide dismutase SOD1 localises to fungal lesion sites (black arrows). The SOD1-positive regions correspond to areas occupied by the immune infiltrates, suggesting staining of mouse and not fungal SOD1. The staining is representative of transverse kidney sections from three biological replicates...

Oligonucleotide primers used in construction of C. albicans mutant strains. (DOCX)

Oligonucleotide primers and UPL probes for fungal and mammalian gene expression analyses. (DOCX)

Normalised qRT-PCR data for Fig 3B. (XLSX)

Normalised qRT-PCR data for Fig 3C. (XLSX)

Oligonucleotide primers and UPL probes for ploidy verification of C. albicans mutant strains. (DOCX)

Normalised qRT-PCR data for Fig 2D. (XLSX)

Normalised qRT-PCR data for Fig 1A. (XLSX)

Normalised qRT-PCR data for S4 Fig. (XLSX)

Normalised qRT-PCR data for Fig 5E. (XLSX)

Normalised qRT-PCR data for Fig 5F. (XLSX)

Normalised qRT-PCR data for Fig 3A. (XLSX)

A network of conserved proteases known as the intramitochondrial quality control (IMQC) system is central to mitochondrial protein homeostasis and cellular health. IMQC proteases also appear to participate in establishment of signaling cues for mitochondria-to-nucleus communication. However, little is known about this process. Here we show that in...

Fever is a universal response to infection, and opportunistic pathogens such as Candida albicans have evolved complex circuitry to sense and respond to heat. Here we harness RNA-seq and ChIP-seq to discover that the heat shock transcription factor, Hsf1, binds distinct motifs in nucleosome-depleted promoter regions to regulate heat shock genes and...

Supplementary Figures 1-7, Supplementary Tables 1-4, Supplementary References

Constitutively bound and heat shock bound Hsf1 targets identified by ChIP-seq.

RNA-seq of wild-type and HSP90 depleted cells in the absence and presence of heat shock. Log2 Fold change between conditions tested and transcript levels of each sample for three biological replicates included.

GO terms of Hsf1 bound genes grouped by specific catagories using Candida Genome Database GO Term Finder function.

Hsf1 motif analysis. Bioinformatic analysis of C. albicans genome to identify the common Hsf1 motifs identified by ChIP-seq analysis in promoters (1 kb upstream of ATG) of all genes.

GO terms of HSP90 depleted genes in the absence of any stress grouped by specific catagories using Candida Genome Database GO Term Finder function.

GO term processes of all Hsf1 bound genes. Hsf1 targets were catagorised into processes using Candida Genome Database GO Slim Mapper function.