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Maes, Martine; Orye, Kristien; Bobev, S. G.; Devreese, Bart; Beeumen, Jozef Van; Bruyn, André De; Busson, Roger; Herdewijn, Piet; Morreel, Kris; Messens, Eric

doi:10.1023/a:1012215201253

Cited by 34 publications

(4 citation statements)

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“…amylovora produces the EPS amylovoran, a heteropolymer whose monomeric subunits consist of one glucuronic acid and four galactose residues, with pyruvate and acetate groups (29). Mutants lacking amylovoran synthesis are nonpathogenic (30)(31)(32), and amylovoran production is positively correlated with the virulence of natural isolates on apple seedlings and trees (33,34). Amylovoran biosynthesis genes are located in the 12-gene ams operon, which is transcribed as a single 16-kb mRNA (2).…”

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confidence: 99%

Virulence Genetics of anErwinia amylovoraPutative Polysaccharide Transporter Family Member

et al. 2020

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The Gram-negative enterobacterium Erwinia amylovora causes fire blight disease in apple and pear trees. Lipopolysaccharides and the exopolysaccharide amylovoran are essential E. amylovora virulence factors. We found that mutations to rfbX disrupted amylovoran production and virulence in apple fruits and tree shoots, and that deletion of yibD suppressed the rfbX mutant phenotype. Expression of yibD was about ten-fold higher in ΔrfbX compared to wild-type. A forward genetic suppressor screen in the ΔrfbX mutant uncovered multiple mutations in yibD and supported the conclusion that the virulence defect of rfbX mutants is due to reduced amylovoran production. The yibD and rfbX genes are expressed as a two-gene operon, yibDrfbX. The rfbX gene encodes a previously-uncharacterized putative polysaccharide subunit transporter, while yibD encodes a predicted glycosyltransferase. Mutation of rfbX did not have a detectable effect on lipopolysaccharide patterns; however, overexpression of yibD in both the wild-type and ΔyibDrfbX genetic backgrounds disrupted both amylovoran and lipopolysaccharide production. Additionally, overexpression of yibD in ΔyibDrfbX inhibited bacterial growth in amylovoran-inducing medium. This growth inhibition phenotype was used in a forward genetic suppressor screen and reverse genetics tests to identify several genes involved in lipopolysaccharide production which, when mutated, restored the ability of ΔyibDrfbX overexpressing yibD to grow in amylovoran-inducing medium. Remarkably, all the lipopolysaccharide gene mutants tested were defective in lipopolysaccharide and amylovoran production. These results reveal a genetic connection between amylovoran and lipopolysaccharide production in E. amylovora. IMPORTANCE This study discovered previously unknown, genetic connections between exopolysaccharide and lipopolysaccharide production in the fire blight pathogen Erwinia amylovora. This represents a step forward in our understanding of the biology underlying the production of these two macromolecules. Fire blight is an economically important disease that impacts the production of apples and pears worldwide. Few fire blight control measures are available, and growers rely heavily on antibiotic applications at bloom time. Both exopolysaccharide and lipopolysaccharide are E. amylovora virulence factors. Our results indicate that overexpression of the yibD gene in E. amylovora disrupts both lipopolysaccharide production and exopolysaccharide production. This effect could potentially be used as the basis for development of an antivirulence treatment for the prevention of fire blight disease.

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confidence: 99%

Virulence Genetics of anErwinia amylovoraPutative Polysaccharide Transporter Family Member

et al. 2020

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“…Despite E. amylovora's genome homogeneity (Mann et al, 2013), variability in the virulence and EPS production among E. amylovora strains is usually reported (Puławska and Sobiczewski, 2012;Popovićet al, 2020;Mendes et al, 2022). A link between EPS and virulence has also been established (Maes et al, 2001). The most of the phenotypic diversity observed among strains is probably due to different plasmid and genomic island content (Mann et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

Fire blight rootstock infections causing apple tree death: A case study in high-density apple orchards with Erwinia amylovora strain characterization

et al. 2023

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A devastating outcome of fire blight in apple trees is the infection of rootstock, which leads to canker development. Fire blight cankers are infected zones of dead bark on perennial branches, trunk, or rootstock that develop after fire blight pathogen Erwinia amylovora invades wood. Cankers can girdle the trunk, branches and rootstock leading to tree death and production losses, especially significant in high-density orchards. An accurate diagnosis of trunk and rootstock blight is a top challenge for apple growers because fire blight cankers can be visually misdiagnosed with cankers caused by less frequent Oomycete and fungal pathogens (e.g., Phytophthora spp., Botryosphaeria dothidea, B. obtusa, Valsa mali). In addition, detecting E. amylovora in apple rootstocks is essential because this pathogen also causes asymptomatic infections. Accurate fire blight diagnosis is necessary to inform the complete removal of infected trees from the orchard and help replanting efforts while preventing further pathogen dissemination. To determine apple tree losses caused by fire blight rootstock infections, PCR was used to detect E. amylovora in symptomatic and asymptomatic rootstocks for two years. Rootstock canker incidence and tree death were rated in selected infection foci on seven commercial apple orchards in New York. Each infection focus consisted of central rootstock-blighted tree and the nearest surrounding edge trees showing no rootstock blight. E. amylovora strains collected from these seven orchards and other orchards in New York were characterized. In the first year, most of the orchards showed E. amylovora detection rates of 10.7 – 45.3% in asymptomatic rootstocks on the edge trees immediately surrounding visibly infected i.e. rootstock-blighted central trees. One year later, 20.8 – 56.3% cankered rootstocks were detected on the edge trees and from zero to 35.4% dead edge trees were recorded. However, the PCR from sampled edge rootstocks one year later showed no pathogen detections. E. amylovora rootstock strains showed slight variability in enzymatic activity, copper sensitivity, virulence, and exopolysaccharide production. These results elucidate the role and importance of rootstock infections for apple tree survival, the presence of latent fire blight infections, and the valuable utility of molecular detection methods to assist apple tree removal after epidemics.

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“…Molecules 2023, 28, 7774 2 of 11 pathogenicity of E. amylovora [17] and, as such, it is finely regulated. One regulatory pathway involves a Low-Molecular Weight Protein Tyrosine Phosphatase (LMW-PTP) called AmsI (EaAmsI), encoded in the ams operon [9].…”

Section: Introductionmentioning

confidence: 99%

“…A strain of E. amylovora deficient in amylovoran production loses the ability to infect apple plants. Indeed, amylovoran biosynthesis is fundamental for the host-specific pathogenicity of E. amylovora [17] and, as such, it is finely regulated. One regulatory pathway involves a Low-Molecular Weight Protein Tyrosine Phosphatase (LMW-PTP) called AmsI (EaAmsI), encoded in the ams operon [9].…”

Section: Introductionmentioning

confidence: 99%

Determination and Kinetic Characterization of a New Potential Inhibitor for AmsI Protein Tyrosine Phosphatase from the Apple Pathogen Erwinia amylovora

Albani,

Polsinelli,

Mazzei

et al. 2023

Molecules

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Erwinia amylovora is a Gram-negative bacterium, responsible for the fire blight disease in Rosaceae plants. Its virulence is correlated with the production of an exopolysaccharide (EPS) called amylovoran, which protects the bacterium from the surrounding environment and helps its diffusion inside the host. Amylovoran biosynthesis relies on the expression of twelve genes clustered in the ams operon. One of these genes, amsI, encodes for a Low Molecular Weight Protein Tyrosine Phosphatase (LMW-PTP) called EaAmsI, which plays a key role in the regulation of the EPS production pathway. For this reason, EaAmsI was chosen in this work as a target for the development of new antibacterial agents against E. amylovora. To achieve this aim, a set of programs (DOCK6, OpenEye FRED) was selected to perform a virtual screening using a database of ca. 700 molecules. The six best-scoring compounds identified were tested in in vitro assays. A complete inhibition kinetic characterization carried out on the most promising molecule (n-Heptyl β-D-glucopyranoside, N7G) showed an inhibition constant of 7.8 ± 0.6 µM. This study represents an initial step towards the development of new EaAmsI inhibitors able to act as antibacterial agents against E. amylovora infections.

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Cited by 34 publications

References 20 publications

Virulence Genetics of anErwinia amylovoraPutative Polysaccharide Transporter Family Member

Virulence Genetics of anErwinia amylovoraPutative Polysaccharide Transporter Family Member

Fire blight rootstock infections causing apple tree death: A case study in high-density apple orchards with Erwinia amylovora strain characterization

Determination and Kinetic Characterization of a New Potential Inhibitor for AmsI Protein Tyrosine Phosphatase from the Apple Pathogen Erwinia amylovora

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