Microstructural mechanisms of specific bioresistance to chemical pollutants
While relevant in their own right, the tasks of modelling, understanding and predicting the behaviour of chemical pollutants that pose a danger to humans and the environment are becoming particularly acute in connection with the war in Ukraine. The use of weapons of mass destruction leads, among other things, to uncontrolled contamination of our country’s territory with a wide variety of chemical pollutants, including both substances that are totally harmful to humans and other living organisms and compounds similar to pesticides (zoocides, fungicides, herbicides), which are widely used, in particular, in agriculture and usually affect very specific biomolecular targets. The solution of the above problems, as well as the tasks of effective neutralisation of chemical factors hazardous to human health, if they are (at least to some extent) biospecific, includes an essential component of understanding the microstructural mechanisms of their interaction with the relevant biomolecular targets and the mechanisms that ensure the resistance/adaptability of living organisms to these compounds. Accordantly to our investigations, there are several mechanisms of resistance increase subdivided into two groups:
resistance as a result of amino acid substitutions in pollutant biomolecular target (figure 1, 2)
resistance provided by the cellular protective systems (figure 3, 4)
Figure 1. Substitutions of Arg-243-Met (A) and Arg-243-Lys (B) in the α-tubulin molecule of the weed annual ryegrass Lolium rigidum Gaudin cause structural changes in the binding site of dinitroaniline compounds and lead to an increase in the free energy of interaction with the herbicide trifluralin by 146 and 176 kJ/mol, respectively. Similar mechanisms of dinitroaniline resistance were demonstrated for goosegrass (Eleusine indica (L.) Gaerth.).
Figure 2. Substitutions of Thr-102-Ser and Thr-102-Ile in the molecule of 5-enolpyruvylshikimate-3-phosphate synthetase of the weed Tridax procumbens L. ) change the contributions of individual amino acids to the binding energy of both the natural substrate phosphoenolpyruvate (PEP) (C) and the herbicide glyphosate (D), and the free energy of PEP binding decreases by 45.4 kJ/mol due to Thr-102-Ser substitution, which means a sharp increase in affinity for the natural substrate.
Figure 3. Aldoketoreductase 4 (EcAKR4-1) of awnless barnyard grass (Echinochloa colona (L.) Link) has both reductase and oxidase activity (mediated by oxidation/reduction of NADPH/NADP+ cofactor) and is able to effectively oxidise glyphosate with subsequent formation of aminomethylphosphonic acid and glyoxalate, which are non-toxic to plant cells.
Figure 4. The ATP-dependent cassette transporter ABCC8, localised in the cytoplasmic membrane of awnless barnyard grass, is able to efficiently bind glyphosate molecule in its cargo site, that causes a change in the transporter conformation from inward (left) to outward (right) orientation with subsequent release of the pollutant molecule into the extracellular space.
Lu, H., Liu, Y., Li, M., Han, H., Zhou, F., Nyporko, A., Yu, Q., Qiang, S., Powles, S. (2023) Multiple Metabolic Enzymes Can Be Involved in Cross-Resistance to 4-Hydroxyphenylpyruvate-Dioxygenase-Inhibiting Herbicides in Wild Radish Journal of Agricultural and Food Chemistry 71 (24), P.9302–9313.
Wang, J., Lian, L., Qi, J., Fang, Y., Nyporko, A., Yu, Q., Bai, L. and Pan, L. (2023), Metabolic resistance to acetolactate synthase-inhibitors in Beckmannia syzigachne: Identification of CYP81Q32 and its transcription regulation. Plant Journal. Accepted Author Manuscript. https://doi.org/10.1111/tpj.16227
Zhou F.-Y., Han H., Han Y.-J., Nyporko A., Yu Q., Beckie H.J., Powles S.B. (2022) Aldo-keto reductase may contribute to glyphosate resistance in Lolium rigidum // Pest Management Science, DOI: 10.1002/ps.7325
Zhang C., Yu, Q., Han H, Yu C. Nyporko A., Tian X., Beckie H., Powles S. (2022), A naturally evolved mutation (Ser59Gly) in glutamine synthetase confers glufosinate resistance in plants // Journal of Experimental Botany, 73 (7), P. 2251 – 2262.
Pan L., Yu Q., Wang J., Han H., Mao L., Nyporko A., Maguza A., Fan L., Bai L., Powles S. (2021) An ABCC-type transporter endowing glyphosate resistance in plants // Proceedings of the National Academy of Sciences of the United States of America, 118(16), e2100136118
Pan L., Yu Q., Han H., Mao L., Nyporko A., Fan L., Bai L., Powles S. (2019) Aldo-keto Reductase Metabolizes Glyphosate and Confers Glyphosate Resistance in Echinochloa colona // Plant Physiology Vol.181, N 4. P. 1519-1534
Li J., Peng Q., Han H., Nyporko A., Kulynych T., Yu Q., Powles S. (2018) Glyphosate Resistance in Tridax procumbens via a Novel EPSPS Thr-102-Ser Substitution // Journal of Agricultural and Food Chemistry. Vol 66. N 30. P. 7880-7888.
Chu Z., Chen J., Nyporko A., Han H., Yu Q. and Powles S. (2018) Novel α-tubulin mutations conferring resistance to dinitroaniline herbicides in Lolium rigidum // Frontiers in Plant Science 9:97. doi: 10.3389/fpls.2018.00097
Contact: head of department Alex Nyporko (email@example.com),
Projects:Extreme Science and Engineering Discovery Envinronment (XSESDE, USA) project TG-DMR110088 «Multiscale Research in Nanotoxicity» ” (2011-2022)