Biology subjects

McAlister, J. A.

Publications and source records attributed to McAlister, J. A..

5 recordsLinked to original sources

bioRxiv2025

Mycotoxin-driven proteome remodeling reveals limited activation of Triticum aestivum responses to emerging chemotypes integrated with fungal modulation of ergosterols

Fusarium head blight (FHB), mainly caused by Fusarium graminearum, is a globally important wheat disease reducing yield and grain quality. The pathogen produces mycotoxins deoxynivalenol (DON), 3-acetyl DON (3ADON), 15-acetyl DON (15ADON), and nivalenol (NIV), which threaten food and feed safety. During the past 15 years, surveillance has identified nove trichothecenes 3ANX and NX, which show increased virulence compared to DON. In this study, we investigated the effects of 15ADON/3ANX chemotype on both wheat and F. graminearum proteomes to identify proteins and pathways responsive to the emerging mycotoxin chemotype. We defined a core wheat proteome across all strains (15ADON- and 15ADON/3ANX-producing, and untreated controls) to explore changes in protein abundance associated with defense response, grain development, and reduced photosynthesis upon infection. Conversely, we identified 32 wheat proteins exclusively produced in the presence of 15ADON/3ANX strains, providing further insight into chemotype-specific responses of wheat. Additionally, assessment from the fungal perspective, reported 119 proteins exclusive to the 15ADON/3ANX strains, including those associated with virulence and mycotoxin production. Lastly, investigation of strain-specific proteome changes showed a significant reduction in mycotoxin protective mechanisms in wheat upon exposure to two 15ADON/3ANX strains, as well as a novel connection between elevated ergosterol biosynthesis and 15ADON/3ANX producing strains. Together, our study characterizes distinct protein production profiles in wheat and F. graminearum in response to 3ANX and provides evidence that these molecular changes influence fungal virulence and host defense responses.

plant biology↗

bioRxiv2025

Global proteomic analysis of Cryptococcus neoformans clinical strains reveals significant differences between latent and lethal infection

To predict the outcomes of disseminated fungal disease, a deeper understanding of host-pathogen interactions at the site of infection is needed to identify targets for clinical intervention and diagnostic development. Cryptococcus neoformans is the causative agent of cryptococcosis, the largest infectious killer of individuals living with HIV. Cryptococcal infection begins in the lungs, with loss of immunological control leading to disseminated central nervous system disease and death. Using advanced mass spectrometry-based proteomic techniques, in vivo infection models, and patient-derived clinical strains, we explored the proteomic profiles of C. neoformans infections related to differences in strain virulence. Our findings reveal that non-lethal latent infection produces a proteomic response that differs significantly from the response caused by lethal infections, and that the proteomic profiles of typical and hypervirulent infections are markedly similar despite differences in time-to-death. Overall, the mouse pulmonary proteomic response in latent infection is defined by enrichment of proteins and pathways involved in extracellular matrix organization, cell adhesion, and structural changes, while the lethal infection is dominated by host-defense, translation, and metabolic processes. These results provide clinically relevant information on how infections caused by different Cryptococcus strains may produce significantly different outcomes. We also identified abundant fungal proteins that could be future drug targets in latent and lethal cryptococcal infection. IMPORTANCECryptococcus neoformans is a fungal pathogen that causes substantial morbidity and mortality in immunocompromised individuals. The initial infection begins in the lungs after exposure to inhaled spores after which local immune cells respond by either killing or containing the fungal cells. Immunosuppression weakens the immune system and allows fungal cells in the lungs to escape through the circulatory system and invade the central nervous system and cause fatal disease. However, differences between fungal strains influence the severity of disease manifestation. Our group has previously described genetic differences that contribute to strain-specific disease manifestations. In this study, we expanded our analysis to investigate the proteomic differences between strains of C. neoformans to identify candidate proteins and pathways that contribute to disease manifestation. We found that latent infection differs significantly from lethal disease from both the host and pathogen proteomic perspectives and have identified several fungal protein targets for future study.

microbiology↗

bioRxiv2025

Spatiotemporal dynamics of cryptococcal infection reveal novel immune modulatory mechanisms and antifungal targets

The threat and incidence of fungal diseases are increasing, as is the severity and mortality rates associated with these infections. New strategies to combat fungal infections are urgently needed to overcome rising rates of resistance and the emergence of new pathogens. To promote invasion within a host, fungi use highly adapted and regulated virulence factors, and, in turn, the host adopts an active and dynamic immune response to suppress infection. Understanding the interplay between these processes is crucial to move fungal disease management and treatment forward and improve global health outcomes. Within the present study, we tackle these challenges using state-of-the-art mass spectrometry instrumentation to explore proteome remodeling during active infection of Cryptococcus neoformans at an unprecedented depth with spatiotemporal resolution. Our prioritization of three host organs (i.e., lungs, brain, spleen) critical to initiation, progression, and response of disease discovers tissue-specific remodeling across time. Within the lungs, we revealed early and sustained activation of the host immune response integrated with characterization of a promising new antifungal target, and we propose the discovery of a competitive inhibitor for functional target disruption. Within the brain, proteome remodeling aligns with disease progression, and we define a new mechanistic role for haptoglobin in fungal cell modulation, as well as showcasing an adaptive survival response of C. neoformans within an hypoxic environment. Within the spleen, we reveal new dynamics of immune system activation upon cryptococcal infection. Overall, we provide the deepest integrated view of cryptococcal disease dynamics across temporal and spatial scales, revealing unrecognized mechanisms of host immunity and fungal pathogenesis that offer new avenues for targeted therapeutic intervention and disease management.

microbiology↗

bioRxiv2025

Whole blood proteome dynamics defines predictive diagnostic and prognostic signatures of cryptococcal infection

Across the globe, fungi are impacting the lives of millions of people through the development of infections ranging from superficial to systemic with limited treatment options. To effectively combat fungal disease, rapid and reliable diagnostic methods are required, including current methodologies using antigen detection, culturing, microscopy, and molecular tools. However, the flexibility of these platforms to diagnose infection using non-invasive methods and predict the outcome of disease are limited. In this study, we apply state-of-the-art mass spectrometry-based proteomics to perform dual perspective (i.e., host and pathogen) profiling of cryptococcal infection. Whole blood collected over a temporal scale following murine model challenged with the human fungal pathogen, Cryptococcus neoformans, detected >3,000 host proteins and 160 fungal proteins. From the host perspective, temporal regulation of known immune-associated proteins, including eosinophil peroxidase and lipocalin-2, along with suppression of lipoproteins, demonstrated infection- and time-dependent host remodeling. Conversely, from the pathogen perspective, known and putative virulence-associated proteins were detected, including proteins associated with fungal extracellular vesicles and host immune modulation. We also observed and validated a new mechanism of immune system response to C. neoformans through modulation of haptoglobin. Further, we assessed the predictive power of dual perspective proteome profiling toward prognostics of cryptococcal infection and report a previously undisclosed integration among virulence factor production, immune system modulation, and individual model survival. Together, our findings pose novel biomarkers of cryptococcal infection from whole blood and highlight the potential of personal proteome profiles to determine the prognosis of cryptococcal infection, a new parameter in fungal disease management.

microbiology↗

bioRxiv2024

HEPN-AbiV is an RNase in the antiphage system AbiV

Prokaryotes and eukaryotes possess defense systems, which can be either innate or acquired, to protect against viral infections. At the bacterial population level, abortive infection (Abi) serves as an innate immune defense mechanism against phage invasion. The AbiV antiviral system is prevalent in several bacterial genomes and exhibits diverse characteristics in terms of gene composition and evolution. Our investigation into the Lactococcus AbiV system revealed a novel two-component system, abiV1 and abiV2, both of which are essential for its function as a type III toxin-antitoxin system. The toxin component AbiV (product of abiV1) is an RNase belonging to the HEPN (Higher Eukaryotes and Prokaryotes Nucleotide-binding) superfamily as it carries the consensus Rx4-6H motif. In vivo assays coupled with mass spectrometry showed that the lactococcal AbiV was expressed in the presence or absence of phages while in vitro experiments demonstrated that AbiV1 degraded ribosomal RNA but not mRNA. On the other hand, the antitoxin component (abiV2) was found to function as an RNA molecule that inhibited the nuclease activity of the AbiV1 toxin. The structural characterization of AbiV revealed that this RNase utilizes a large patch of positively charged area across the dimer to anchor RNA molecules. In addition, we showed that the AbiV N-terminal region (amino acids 1 to 23) is crucial for its RNase activity as a truncated AbiV lacking this segment adopted distinct conformational states incompatible with RNA binding. This study provided novel insights into the mode of action of the antiviral system AbiV.

biochemistry↗