The use of small molecules to modulate full-length PDK1 kinase conformation and substrate specificity towards Akt (Póster)

MARIANA SACERDOTI; LISSY Z. F. GROSS; KARIN ZEHNDER; ANDREW M. RILEY; ABHIJEET GHODE; EVELYN SUESS; MARÍA V. CAPELLARI; SEBASTIÁN KLINKE; GANESH S. ANAND; PEDRO F. ARAMENDÍA; DMITRI SVERGUN; MELISSA A. GRAEWERT; ALEJANDRO E. LEROUX; BARRY V. POTTER; CARLOS J. CAMACHO; RICARDO M. BIONDI

Rosario

Congreso; LIX Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB); 2023

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB)

3-Phosphoinositide-dependent protein kinase 1 (PDK1) is a master kinase of the PI3-kinase signalling pathway that phosphorylates at least 23 other evolutionary related AGC kinases. It has an N-terminal kinase domain, a linker region and a C-terminal PH domain that binds PIP3 and other inositol polyphosphates. Our laboratory has previously used a chemical and structural biology approach to study and characterize the bidirectional allosteric regulation between the ATP-Binding site of PDK1 and the PIF pocket, a regulatory site located on the small lobe of the kinase domain. Phosphorylation by PDK1 is a necessary step to activate several other kinases, such as Akt, SGK, S6K and PKC. The interaction between substrate kinases (except Akt) and PDK1 is mediated through a docking interaction with the PIF pocket of PDK1. Interestingly, the interaction with the PIF pocket of PDK1 is not a requirement for the phosphorylation of PKB/Akt after PI3-kinase activation, but both proteins can colocalize at the cell membrane by binding PIP3 through their PH domains. We now describe the conformational landscape of full length PDK1, identifying one dimeric conformation and at least two distinct monomeric conformations. What´s more, the conformations appear to have distinct substrate specificity and PIF pocket availability, related to the relative position of the PH domain.  Small molecules that bind to different sites on PDK1 were able to disrupt dimers and stabilize specific monomeric conformations with different abilities to phosphorylate Akt. Our methods include a multitude of biochemical, biophysical and bionfomatical assays. Given the relevance of PDK1 in signaling pathways that control cell growth and survival, this research could contribute to the development of compounds to selectively inhibit PDK1 activation of Akt for cancer treatments.