Characterization of a potential post-translational regulatory mechanism of Kcs1 protein function during the DNA damage response in Saccharomyces cerevisiae.

• Grant number: 25/00749-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: December 31, 2025
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: José Renato Rosa Cussiol
• Grantee: Giuliana Monteiro
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
• Associated research grant: 24/10865-3 - Inositol Polyphosphates: Mechanisms of Action and Integration with DNA Damage Response, AP.R

Abstract

Abstract: The Kcs1 protein (IP6K1/2/3 in humans) is an inositol pyrophosphate kinase responsible for the synthesis of inositol pyrophosphates (PP-IPs). PP-IPs are a ubiquitous class of highly charged, water-soluble molecules conserved from yeast to humans, playing essential roles in cellular homeostasis. Phosphoproteomic studies have identified Kcs1 as a phosphoprotein, being phosphorylated on different serine and threonine residues under various physiological conditions. A recent study showed that the Snf1 protein kinase (AMPK in humans) phosphorylates Kcs1 at two serine residues, modulating its kinase activity during nitrogen deprivation, suggesting that Kcs1 activity may be post-translationally regulated. This project aims to identify, via mass spectrometry, Kcs1 phosphorylated amino acid residues during genotoxic stress induced by zeocin. Once the residues are identified, we will clone Kcs1 and perform site-directed mutagenesis to replace the Ser/Thr residues with Ala, creating a phosphomutant. We will evaluate whether the expression of the phosphomutant exhibits phenotypes similar to a kcs1¿ strain, such as hypersensitivity to genotoxins, defects in cell cycle replication progression, and alterations in DDR markers.