Biology subjects

Moayeri, M.

Publications and source records attributed to Moayeri, M..

4 recordsLinked to original sources

bioRxiv2025

Environmental Regulation of Toxin Production in Bacillus anthracis

Pathogenic Bacillus anthracis strains carry two plasmids - pX01, which encodes a tripartite protein exotoxin complex (PA, LF, and EF); and pX02, which encodes a poly-D-gamma-glutamic acid capsule. A multidomain transcription factor, AtxA, regulates the expression of these virulence genes. AtxA has two DNA-binding Helix-Turn-Helix (HTH) domains, two phosphoenolpyruvate:carbohydrate phosphotransferase system regulatory domains (PRD1 and PRD2), and a putative EIIB domain (a component of PTS sugar transport EII-complexes). Previous studies showed that glucose and CO2 increase AtxA-dependent toxin gene transcription, along with histidine phosphorylation of PRD1 and PRD2. Our transcriptional profiling of virulence factors, PA secretion, and fluorescent reporter strain analyses confirms a synergistic effect of glucose and CO2 on AtxA-dependent toxin production. Deletion of AtxA ({Delta}atxA) significantly reduced glucose uptake in bacteria, suggesting that AtxA may act within the glucose-PTS system. Mutation analysis of the EIIB domain of AtxA identified the cysteine at position 402 as essential for the transcriptional activity of AtxA. Deletion of glucose PTS permease PtsG ({Delta}ptsG) significantly reduced the expression of PA, LF, and EF. Loss of PtsG also caused attenuation in a mouse model of infection. Intracellular imaging using FLIM confirms a physical interaction of PtsG and AtxA through EIIB domain of AtxA. Using phosphomimetic and phosphoablative mutants of AtxA, we confirmed that the physical interaction of PtsG and AtxA is essential for AtxA activity. Finally, the synergy between glucose and CO2 was targeted by deleting pyruvate carboxylase Pyc ({Delta}pyc), which regulates anaplerosis. This deletion confirms that Pyc stimulates the level of phosphoenolpyruvate (PEP) and increases the phosphorelay in glucose-PTS to enhance AtxA activity. Therefore, we propose that a histidine-phosphorelay from PEP regulates AtxA via PTS enzymatic activity, impacting AtxA activity through physical interaction of AtxA and PtsG. Finally, we propose AtxA as an integral component of the glucose-PTS, where transcriptional activity of AtxA is regulated by environmental signals including glucose and CO2.

molecular biology↗

bioRxiv2025

A novel AAA+ ATPase required for sporulation and stress response in Bacillus anthracis

AAA+ proteins function as molecular machines that utilize ATP to perform diverse cellular functions, including protein homeostasis, stress regulation, and cell cycle/developmental processes. In this study, we identified a novel AAA+ ATPase BAS PrkA in B. anthracis Sterne 34F2 which has 88 % protein homology to Bacillus subtilis PrkA. Conserved domain analysis confirms BAS PrkA has an N-terminal AAA+ ATPase domain with characteristic Walker A and Walker B motifs and a conserved secondary region of homology (SRH) domain, along with a C-terminal cAMP-dependent protein kinase domain. Based on Alpha Fold3 predicted structure, we classified BAS PrkA as part of Clade III of the AAA+ superfamily. Contrary to the reported enzymatic activity in B. subtilis PrkA, we observed that BAS PrkA has negligible protease and kinase activity under in-vitro conditions. Nonetheless, BAS PrkA plays a significant role in regulating sporulation. It is temporally expressed during Stages II to VI during sporulation. A null mutant of BAS PrkA exhibits severe sporulation defects, with reduced spore viability, and down regulation of genes related to spore-coat formation. These phenotypes were restored in a complementation strain expressing BAS PrkA ectopically. Additionally, the null mutant strain showed compromised growth under ionic-osmotic stress conditions. Analysis of the BAS PrkA interactome revealed enrichment of two proteins, ProA and EzrA, that are implicated in osmotic stress response and the sporulation process, respectively. These findings show that BAS PrkA plays a critical role in sporulation and osmotic stress response in B. anthracis.

microbiology↗

bioRxiv2021

Direct imaging of anthrax intoxication in animals reveals shared and individual functions of CMG-2 and TEM-8 in cellular toxin entry

The virulence of Bacillus anthracis is linked to the secretion of anthrax lethal toxin and anthrax edema toxin. These binary toxins consist of a common cell-binding moiety, protective antigen (PA), and the enzymatic moieties, lethal factor (LF) and edema factor (EF). PA binds either of two specific cell surface receptors, capillary morphogenesis protein-2 (CMG-2) or tumor endothelial marker-8 (TEM-8), which triggers the binding, endocytosis, and cytoplasmic translocation of LF and EF. The cellular distribution of functional TEM-8 and CMG-2 receptors during anthrax toxin intoxication in animals is not fully elucidated. Herein, we describe a novel assay to image anthrax toxin intoxication in live animals, and we use the assay to visualize TEM-8- and CMG-2-dependent intoxication. Specifically, we generated a chimeric protein consisting of the N-terminal domain of LF fused to a nuclear localization signal-tagged Cre recombinase (LFn-NLS-Cre). When PA and LFn-NLS-Cre were co-administered to transgenic mice that ubiquitously express a red fluorescent protein in the absence of Cre activity and a green fluorescent protein in the presence of Cre activity, anthrax toxin intoxication could be visualized at single-cell resolution by confocal microscopy. By using this assay, we show that CMG-2 is critical for intoxication in the liver and heart, whereas TEM-8 is required for full intoxication in the kidney and spleen. Other tissues examined were largely unaffected by single deficiences in either receptor, suggesting extensive overlap in TEM-8 and CMG-2 expression. The novel assay will be useful for basic and clinical/translational studies of Bacillus anthracis infection and for identifying on- and off-targets for reengineered toxin variants in the clinical development of cancer treatments. BackgroundAssays for imaging of anthrax toxin intoxication in animals are not available. ResultsAnthrax toxin-Cre fusions combined with fluorescent Cre reporter mice enabled imaging of anthrax toxin intoxication in animals. ConclusionShared and distinct functions of toxin receptors in cellular entry were uncovered. Significance. A simple and versatile assay for anthrax toxin intoxication is described.

pathology↗

bioRxiv2019

Investigating Transfusion-Related Sepsis using Culture-Independent Metagenomic Sequencing

BackgroundTransfusion-related sepsis remains an important hospital infection control challenge. Investigating septic transfusion events is often restricted by the limitations of bacterial culture in terms of time requirements and low yield in the setting of prior antibiotic administration.\n\nMethodsIn three Gram-negative septic transfusion cases, we performed mNGS of direct clinical blood specimens in addition to standard culture-based approaches utilized for infection control investigations. Pathogen detection leveraged IDSeq, a new open-access microbial bioinformatics portal. Phylogenetic analysis was performed to assess microbial genetic relatedness and understand transmission events.\n\nResultsmNGS of direct clinical blood specimens afforded precision detection of pathogens responsible for each case of transfusion-related sepsis, and enabled discovery of a novel Acinetobacter species in a platelet product that had become contaminated despite photochemical pathogen reduction. In each case, longitudinal assessment of pathogen burden elucidated the temporal sequence of events associated with each transfusion-transmitted infection. We found that informative data could be obtained from culture-independent mNGS of residual platelet products and leftover blood specimens that were either unsuitable or unavailable for culture, or that failed to grow due to prior antibiotic administration. We additionally developed methods to enhance accuracy for detecting transfusion-associated pathogens sharing taxonomic similarity to contaminants commonly found in mNGS library preparations.\n\nConclusionsCulture-independent mNGS of blood products afforded rapid and precise assessment of pathogen identity, abundance and genetic relatedness. Together, these challenging cases demonstrated the potential for metagenomics to advance existing methods for investigating transfusion-transmitted infections.

microbiology↗