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

Molecules. 2023 Nov 25;28(23):7774. doi: 10.3390/molecules28237774.

Abstract

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.

Keywords: EPS production regulation; Erwinia amylovora; amylovoran; exopolysaccharide; fire blight; in vitro assays; inhibition constant; molecular docking; protein tyrosine phosphatase; virtual screening.

MeSH terms

  • Anti-Bacterial Agents / metabolism
  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Erwinia amylovora*
  • Erwinia* / genetics
  • Erwinia* / metabolism
  • Malus* / metabolism
  • Plant Diseases / microbiology
  • Polysaccharides, Bacterial / metabolism
  • Protein Tyrosine Phosphatases / genetics
  • Protein Tyrosine Phosphatases / metabolism
  • Virulence

Substances

  • Protein Tyrosine Phosphatases
  • Anti-Bacterial Agents
  • Polysaccharides, Bacterial
  • Bacterial Proteins

Grants and funding

The research leading to these results has received funding from the Free University of Bolzano under the IMPACTS project (grant number 1811) and TowEr (grant number 2971). Plasmid pETM-11 was obtained from the European Molecular Biology Laboratory under a signed Material Transfer Agreement. We acknowledge CF Biophysical Techniques of CIISB, Instruct-CZ Centre, supported by MEYS CR (LM2018127). Financial support was provided by Instruct-ERIC (PID 12403). F.M. was supported by Ministero dell’Istruzione, dell’Università e della Ricerca (RFO grant 2020) and by Consorzio Interuniversitario Risonanze Magnetiche di Metallo Proteine (CIRMMP).