Quareshy, M, Prusinska, J, Kieffer, M et al. (9 more authors) (2018) The tetrazole analogue of the auxin indole-3-acetic acid binds preferentially to TIR1 and not AFB5. ACS Chemical Biology, 13 (9). pp. 2585-2594. ISSN 1554-8929
Abstract
Auxin is considered one of the cardinal hormones in plant growth and development. It regulates a wide range of processes throughout the plant. Synthetic auxins exploit the auxin-signalling pathway and are valuable as herbicidal agrochemicals. Currently, despite a diversity of chemical scaffolds all synthetic auxins have a carboxylic acid as the active core group. By applying bio-isosteric replacement we discovered that indole-3-tetrazole was active by surface plasmon resonance (SPR) spectrometry, showing that the tetrazole could initiate assembly of the TIR1 auxin co-receptor complex. We then tested the tetrazole’s efficacy in a range of whole plant physiological assays and in protoplast reporter assays which all confirmed auxin activity, albeit rather weak. We then tested indole-3-tetrazole against the AFB5 homologue of TIR1, finding that binding was selective against TIR1, absent with AFB5. The kinetics of binding to TIR1 are contrasted to those for the herbicide picloram, which shows the opposite receptor preference as it binds to AFB5 with far greater affinity than to TIR1. The basis of the preference of indole-3-tetrazole for TIR1 was revealed to be a single residue substitution using molecular docking, and assays using tir1 and afb5 mutant lines confirmed selectivity in vivo. Given the potential that a TIR1-selective auxin might have for unmasking receptor-specific actions, we followed a rational design, lead optimisation campaign and a set of chlorinated indole-3-tetrazoles was synthesised. Improved affinity for TIR1 and the preference for binding to TIR1 was maintained for 4- and 6-chloroindole-3-tetrazoles, coupled with improved efficacy in vivo. This work expands the range of auxin chemistry for the design of receptor-selective synthetic auxins.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | Copyright © 2018 American Chemical Society. This is an author produced version of a paper published in ACS Chemical Biology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Auxin; bioisostere; herbicides; tetrazole; synthetic herbicides; rationale; drug-design; SAR; target selectivity |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Biology (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 04 Sep 2018 11:07 |
Last Modified: | 23 Aug 2019 00:42 |
Status: | Published |
Publisher: | American Chemical Society |
Identification Number: | 10.1021/acschembio.8b00527 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:135235 |