Structural and biochemical characterization of the PDK1-S6K and PDK1-PRK2 protein complexes (Póster)

LISSY Z. F. GROSS; FACUNDO GALCERAN; MARIANA SACERDOTI; JIMENA RINALDI; SEBASTIÁN KLINKE; LISANDRO H. OTERO; ALEJANDRO E. LEROUX; RICARDO M. BIONDI

Buenos Aires

Simposio; Simposio "Frontiers in Bioscience 4"; 2023

Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA, CONICET-MPSP)

Protein kinases are very important ON-OFF switches in cells and dysregulation of their activities often lead to diseases, such as cancer or diabetes. Therefore, protein kinases are tightly and selectively regulated. Phosphoinositide-dependent protein kinase 1 (PDK1) is a master AGC kinase of the PI3K signalling pathway that phosphorylates at least other 23 AGC kinases, including Akt/PKB, S6K, SGK, PKC, PRK, among others. Over the years, our laboratory used a chemical and structural biology approach to study and characterize in detail the regulation of PDK1. The structure of the isolated PH domain and the structure and dynamics of the isolated catalytic domain have been described, but information on the structure and conformations of full-length PDK1 are missing. In this poster we show recently published results in which we used an interdisciplinary approach to understand how the full-length protein is regulated and if this regulation mechanism can be manipulated to specifically inhibit the activation of PKB/Akt. We here present a series of experiments obtained using HDX and SAXS on full length PDK1, as well as the crystal structure of the catalytic domain bound to a small compound that stabilizes a particular PDK1 conformation. Our study reveals dynamic conformations of full-length PDK1 in which the location of the linker and the PH domain relative to the catalytic domain determines the selective phosphorylation of PDK1 substrates. On the other hand, we show some preliminary and ongoing results of the interaction between PDK1 and two other kinase substrates (S6K and PRK2) using a chemical biology approach as well as Negative‐stain TEM. We also show how this protein-protein interactions can be modulated by small compounds and metabolites that have orthosteric but also allosteric effects on the protein complex. The study further suggests new approaches for the design of drugs to selectively modulate signaling downstream of PDK1.