Redox regulation and characterization of mitochondria protein phosphatase

• Grant number: 23/13994-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2023
• End date: October 31, 2024
• Field of knowledge: Biological Sciences - Biochemistry - Chemistry of Macromolecules
• Principal Investigator: Luciana Elena de Souza Fraga Machado
• Grantee: Mel Mirra de Carvalho Rachid
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 19/02605-3 - Structural and functional characterization of mitochondrial protein phosphatases by redox metabolism and their role in cell biology, AP.JP

Abstract

Protein phosphatases regulate several cellular functions through the dephosphorylation of their substrates, participating in fundamental cell signaling mechanisms, for example, the response to stress, energy metabolism, and regulation of cell progression. These enzymes are located in cellular compartments such as the cytosol and mitochondria. The knowledge regarding the regulation mechanisms of mitochondrial protein phosphatases is still limited; however, it is known that such proteins play essential roles in a wide spectrum of cellular processes, such as the citric acid cycle and ATP synthesis. In this sense, the present work aims to analyze the redox regulation in vitro and in vivo of the mitochondrial serine/threonine phosphatases proteins PP2Cm and PPTc7 - proteins located in the mitochondrial matrix that are fundamental in the oxidation of branched-chain amino acids and in the regulation of mitochondrial metabolism, respectively. To this end, the optimum pH and temperature for PPTc7 activity will be analyzed, as well as the growth of yeast mutants of both proteins under normal conditions and under oxidative stress. Furthermore, studies will be carried out on the oxidation of PP2Cm and PPTc7 by hydrogen peroxide (H2O2) and at different pH, finally analyzing the reactivation of their activity by ascorbate. Hence, knowing that cytosolic protein phosphatases are highly regulated by redox mechanisms and that mitochondria constitute one of the main sites of cellular oxidant production, it is expected - based on experimental results - that mitochondrial protein phosphatases, such as PPTc7 and PP2Cm, are also regulated by oxidation and reduction processes.