Auxin-binding pocket of ABP1 is crucial for its gain-of-function cellular and developmental roles

article Auxin-binding pocket of ABP1 is crucial for its gain-of-function cellular and developmental roles published yes Peter Grones author 399876EC-F248-11E8-B48F-1D18A9856A87 Xu Chen author 4E5ADCAA-F248-11E8-B48F-1D18A9856A87 Sibu Simon author 4542EF9A-F248-11E8-B48F-1D18A9856A870000-0002-1998-6741 Walter Kaufmann author 3F99E422-F248-11E8-B48F-1D18A9856A870000-0001-9735-5315 Riet De Rycke author Tomasz Nodzyński author Eva Zažímalová author Jirí Friml author 4159519E-F248-11E8-B48F-1D18A9856A870000-0002-8302-7596 JiFr department EM-Fac department Polarity and subcellular dynamics in plants project The plant hormone auxin is a key regulator of plant growth and development. Auxin levels are sensed and interpreted by distinct receptor systems that activate a broad range of cellular responses. The Auxin-Binding Protein1 (ABP1) that has been identified based on its ability to bind auxin with high affinity is a prime candidate for the extracellular receptor responsible for mediating a range of auxin effects, in particular, the fast non-transcriptional ones. Contradictory genetic studies suggested prominent or no importance of ABP1 in many developmental processes. However, how crucial the role of auxin binding to ABP1 is for its functions has not been addressed. Here, we show that the auxin-binding pocket of ABP1 is essential for its gain-of-function cellular and developmental roles. In total, 16 different abp1 mutants were prepared that possessed substitutions in the metal core or in the hydrophobic amino acids of the auxin-binding pocket as well as neutral mutations. Their analysis revealed that an intact auxin-binding pocket is a prerequisite for ABP1 to activate downstream components of the ABP1 signalling pathway, such as Rho of Plants (ROPs) and to mediate the clathrin association with membranes for endocytosis regulation. In planta analyses demonstrated the importance of the auxin binding pocket for all known ABP1-mediated postembryonic developmental processes, including morphology of leaf epidermal cells, root growth and root meristem activity, and vascular tissue differentiation. Taken together, these findings suggest that auxin binding to ABP1 is central to its function, supporting the role of ABP1 as auxin receptor. Oxford University Press2015 eng Journal of Experimental Botany 00035968830001710.1093/jxb/erv177 66165055 - 5065 Grones, Peter, Xu Chen, Sibu Simon, Walter Kaufmann, Riet De Rycke, Tomasz Nodzyński, Eva Zažímalová, and Jiří Friml. “Auxin-Binding Pocket of ABP1 Is Crucial for Its Gain-of-Function Cellular and Developmental Roles.” Journal of Experimental Botany. Oxford University Press, 2015. <a href="https://doi.org/10.1093/jxb/erv177">https://doi.org/10.1093/jxb/erv177</a>. P. Grones et al., “Auxin-binding pocket of ABP1 is crucial for its gain-of-function cellular and developmental roles,” Journal of Experimental Botany, vol. 66, no. 16. Oxford University Press, pp. 5055–5065, 2015. Grones, Peter, et al. “Auxin-Binding Pocket of ABP1 Is Crucial for Its Gain-of-Function Cellular and Developmental Roles.” Journal of Experimental Botany, vol. 66, no. 16, Oxford University Press, 2015, pp. 5055–65, doi:<a href="https://doi.org/10.1093/jxb/erv177">10.1093/jxb/erv177</a>. Grones P, Chen X, Simon S, Kaufmann W, De Rycke R, Nodzyński T, Zažímalová E, Friml J. 2015. Auxin-binding pocket of ABP1 is crucial for its gain-of-function cellular and developmental roles. Journal of Experimental Botany. 66(16), 5055–5065. Grones P, Chen X, Simon S, et al. Auxin-binding pocket of ABP1 is crucial for its gain-of-function cellular and developmental roles. Journal of Experimental Botany. 2015;66(16):5055-5065. doi:<a href="https://doi.org/10.1093/jxb/erv177">10.1093/jxb/erv177</a> P. Grones, X. Chen, S. Simon, W. Kaufmann, R. De Rycke, T. Nodzyński, E. Zažímalová, J. Friml, Journal of Experimental Botany 66 (2015) 5055–5065. Grones, P., Chen, X., Simon, S., Kaufmann, W., De Rycke, R., Nodzyński, T., … Friml, J. (2015). Auxin-binding pocket of ABP1 is crucial for its gain-of-function cellular and developmental roles. Journal of Experimental Botany. Oxford University Press. <a href="https://doi.org/10.1093/jxb/erv177">https://doi.org/10.1093/jxb/erv177</a> 15622018-12-11T11:52:44Z2025-09-23T07:59:07Z