Biology subjects

Preston, G. M.

Publications and source records attributed to Preston, G. M..

5 recordsLinked to original sources

bioRxiv2025

Bacterial pathogen deploys iminosugar galactosyrin to manipulate plant glycobiology

The extracellular space (apoplast) of plants is an important molecular battleground during infection by many pathogens. We previously found that a plant-secreted {beta}-galactosidase BGAL1 acts in immunity by facilitating the release of immunogenic peptides from bacterial flagellin and that Pseudomonas syringae suppresses this enzyme by producing a small molecule inhibitor called galactosyrin. Here, we elucidated the structure and biosynthesis of galactosyrin and uncovered its multifunctional roles during infection. Structural elucidation by cryo-EM and chemical synthesis revealed that galactosyrin is an iminosugar featuring a unique geminal diol attached to the pyrrolidine moiety that mimics galactose binding to the {beta}-galactosidase active site. Galactosyrin biosynthesis branches off from purine biosynthesis and involves three enzymes of which the first is a reductase that is unique in iminosugar biosynthesis. Besides inhibiting BGAL1 to avoid detection, galactosyrin also changes the glycoproteome and metabolome of the apoplast. The manipulation of host glycobiology may be common to plant-associated bacteria that carry putative iminosugar biosynthesis clusters.

plant biology↗

bioRxiv2025

The cause-effect conundrum of local-scale site and soil factors in acute oak decline (AOD)

Background and aimsAcute oak decline (AOD), a decline syndrome affecting mature oaks, involves bacterial pathogens which likely act as opportunists under host stress. Trees displaying symptoms (bleeding cankers) appear in localized clusters, not whole stands. This study investigates the potential involvement of local-scale factors, in interaction with large-scale environmental drivers, in influencing onset and progression of AOD. MethodsAOD-symptomatic (n=30) and asymptomatic trees (n=30) across three UK oak woodlands were assessed for tree characteristics, their surrounding context, and soil properties. ResultsTree health status was linked to significant differences in soil and tree properties across sites. Symptomatic trees exhibited greater loss of crown density, lower local stand (0-20 m) basal area and shallower depth to gleying. Significant differences in soil properties included lower concentrations of Olsen P, total N, and exchangeable Mg in symptomatic trees, alongside higher exchangeable Fe, especially at 40-50 cm depth. Depth to gleying and exchangeable Fe were identified as the most influential predictors of AOD. ConclusionsAOD symptomatic trees may experience seasonal soil water saturation closer to the surface compared to asymptomatic trees, resulting in a higher proportion of their roots being exposed to an anoxic, iron-reducing environment. This study is the first to report such an association between gleying depth, likely seasonal water saturation, and symptom status for AOD. It is unclear whether water balance and associated soil nutrient variations are predisposing factors or consequences of declining tree health, though the identified local-scale factors likely contribute to AOD. A feedback loop is conceptualised where declining tree health worsens soil conditions, creating a negative cycle that accelerates tree decline.

ecology↗

bioRxiv2020

RpoS Contributes to Successful Opportunistic Colonization by Human Enteric Pathogens during Plant Disease

With an increase in foodborne illnesses associated with the consumption of fresh produce, it is important to understand the interactions between human bacterial enteric pathogens and plants. It was previously established that diseased plants can create a permissive environment for opportunistic endophytic colonization of enteric pathogens. However, the factors that contribute to the colonization of enteric pathogens during plant disease are largely unknown. Here, we show that both strain and plant host factors contribute to significantly increased populations of enteric pathogens when co-inoculated with the plant pathogen, P. syringae pv. tomato. The two Salmonella enterica strains DM10000 and 14028S, differ in their ability to metabolize host-derived apoplastic carbohydrates dependent on the sigma factor RpoS. The rpoS gene is an important strain factor for endophytic colonization by S. enterica during plant disease. Our results suggest that rpoS plays a crucial role during in planta colonization, balancing nutrient metabolism and stress responses. ImportanceFoodborne illnesses caused by the bacterial human enteric pathogens, E. coli O157:H7 and S. enterica, often results in vomiting and diarrhea. If left untreated, this illness can cause dehydration and sometimes death of a patient. Both E. coli O157:H7 and S. enterica have caused repeated fresh produce-associated epidemics. Crop disease could promote the ability of plants to act as reservoirs for produce-borne outbreaks. Plant pathogens dampen plant immunity, which allows for a more permissive environment for human enteric pathogens to grow. These internalized enteric pathogen populations are especially dangerous since they cannot be removed by washing alone. Therefore, the need to understand the factors that contribute to the opportunistic colonization of human enteric pathogens during plant disease is apparent. Our research has identified host and strain factors that contribute to opportunistic colonization of diseased plants, which will inform the development of future management strategies to mitigate future outbreaks.

pathology↗

bioRxiv2020

Agromonas: a rapid disease assay for Pseudomonas syringae growth in agroinfiltrated leaves

The lengthy process to generate transformed plants is a limitation in current research on the interactions of the model plant pathogen Pseudomonas syringae with plant hosts. Here we present an easy method called agromonas, where we quantify P. syringae growth in agroinfiltrated leaves of Nicotiana benthamiana using a cocktail of antibiotics to select P. syringae on plates. As a proof of concept, we demonstrate that transient expression of PAMP receptors reduces bacterial growth and that transient depletion of a host immune gene and transient expression of a T3 effector increase P. syringae growth in agromonas assays. We show that we can rapidly achieve structure-function analysis of immune components and test the function of immune hydrolases. The agromonas method is easy, fast and robust for routine disease assays with various Pseudomonas strains without transforming plants or bacteria. The agromonas assay offers reliable opportunity for further comprehensive analysis of plant immunity. One sentence summaryAgromonas is a rapid and robust disease assay to monitor Pseudomonas syringae growth in agroinfiltrated leaves expressing immune components and their suppressors.

plant biology↗

bioRxiv2020

Plasma and Fecal Metabolite Profiles in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition with hallmark behavioral manifestations including impaired social communication and restricted repetitive behavior. In addition, many affected individuals display metabolic imbalances, immune dysregulation, gastrointestinal (GI) dysfunction, and altered gut microbiome compositions. We sought to better understand non-behavioral features of ASD by determining molecular signatures in peripheral tissues. Herein, we present the untargeted metabolome of 231 plasma and 97 fecal samples from a large cohort of children with ASD and typically developing (TD) controls. Differences in lipid, amino acid, and xenobiotic metabolism discriminate ASD and TD samples. We reveal correlations between specific metabolite profiles and clinical behavior scores, and identify metabolites particularly associated with GI dysfunction in ASD. These findings support a connection between GI physiology, metabolism, and complex behavioral traits, and may advance discovery and development of molecular biomarkers for ASD.

biochemistry↗