#800-22 Novel crystal structure of ABI1 protein phosphatase 2C group A and its use in inhibitor design

Body of Abstract:
Reversible protein phosphorylation is a key protein modification involved in the regulation of many cellular processes. Phosphorylation/dephosphorylation processes are catalysed by two groups of enzymes: protein kinases and protein phosphatases. In Arabidopsis, there are more than 1000 genes encoding protein kinases and protein phosphatases. The protein phosphatase ABI1 plays a crucial role in plant growth, development and response to abiotic stresses. Protein phosphatases of type 2C group A are known effectors of the ABA signalling pathway. For decades, understanding ABA perception and signalling has been a major goal of plant research studies. In this study, we present the crystal structure of the ABI1 protein obtained by X-ray crystallography. According to the literature, the structure of ABI1 has only been solved in complex with the active site bound ABA receptor, and it is unclear whether the conformation changes significantly upon substrate or inhibitor binding. The novel crystal structure of the free-standing ABI1 phosphatase provides an opportunity as a new target for the search for molecules as PP2C inhibitors. We present here an approach for the identification of effective inhibitors of ABI1-like PP2C. Overall, the crystal structure of the ABI1 protein provides important insights into its organisation and functional implications. This knowledge paves the way for a comprehensive understanding of the role of the ABI1 protein in plant physiology and crop improvement strategies aimed at enhancing abiotic stress tolerance.