Photoaffinity labelling platform for herbicide binding site determination

Overview

This research platform addresses a critical gap in herbicide development by applying photoaffinity labelling techniques to identify the binding sites of novel herbicidal compounds. While commercial herbicides commonly target amino acid biosynthesis pathways, the potential of inhibiting lysine production in weeds remains commercially unexplored. The platform supports the development of herbicides with novel modes of action by providing robust characterisation of molecular targets, which is essential for rational herbicide design and intellectual property positioning.

The platform has already produced a series of inhibitors targeting enzymes in the lysine biosynthesis pathway, including MBDTA, the first known dual-target herbicidal inhibitor active against both DHDPS and DHDPR enzymes. These compounds have demonstrated confirmed activity in both in vitro and in planta settings, making them strong candidates for further development.

Technical specifications

Key capabilities:

• Synthesis of inhibitor analogues incorporating photoactive diazirine groups for covalent protein labelling upon UV irradiation
• Photoaffinity labelling workflow using isolated plant enzymes, with carbene intermediate formation enabling insertion into protein structures
• Tandem mass spectrometry analysis following protein digestion to identify labelled residues and binding site locations
• Complementary X-ray crystallography for structural validation of inhibitor-enzyme interactions
• Dual-target inhibitor scaffolds including MBDTA, which inhibits both DHDPS and DHDPR enzymes in the lysine biosynthesis pathway

The methodology involves incubating photoactive inhibitor analogues with target enzymes, irradiating with UV light to activate the diazirine moiety, and using proteomics approaches to pinpoint binding locations. One inhibitor containing a diazirine moiety has already been synthesised and confirmed to retain activity against the target enzyme through kinetic studies.

Technology readiness level

The platform is at an early-to-mid stage of development. Initial proof-of-concept studies are planned over a six-month period. Chemical reagents and consumables funding is sought to support synthesis of additional analogues and validation experiments. Compounds have demonstrated confirmed in vitro and in planta herbicidal activity, with binding site characterisation work ongoing. The dual-target inhibitor MBDTA represents a novel chemical entity with potential for further optimisation and development toward commercial herbicide applications.