Targeting of PP2C in budding yeast

Area of Science:

• Biochemistry
• Molecular Biology
• Yeast Genetics

Background:

• Type 2C Ser/Thr phosphatases (PP2Cs) are crucial metal-dependent enzymes found in all domains of life.
• In yeast, seven PP2Cs, termed PTCs, are involved in diverse cellular processes.
• Previous studies suggest roles for PTCs in RNA splicing, stress responses, and cell-cycle regulation.

Purpose of the Study:

• To investigate the role of specific PTCs in the stress-activated High-Osmolarity Glycerol (HOG) mitogen-activated protein kinase (MAPK) pathway in Saccharomyces cerevisiae.
• To elucidate the mechanism by which PTCs are recruited to their substrates within the HOG pathway.

Main Methods:

• Molecular genetic studies to analyze PTC function in the HOG pathway.
• Proteomics to identify interacting proteins and potential substrates.
• Yeast two-hybrid assays to confirm protein-protein interactions.

Main Results:

• Three PTCs (Ptc1, Ptc2, Ptc3) were identified as regulators of the HOG MAPK pathway.
• Proteomics and yeast two-hybrid studies revealed Nbp2 as a protein interacting with Ptc1.
• Nbp2 was demonstrated to function as an adapter, mediating the interaction between Ptc1 and the HOG pathway kinase Pbs2.

Conclusions:

• Ptc1, Ptc2, and Ptc3 play significant roles in regulating the HOG pathway.
• Nbp2 is a key adapter protein that facilitates the interaction between Ptc1 and Pbs2, thereby integrating phosphatases into the HOG signaling cascade.
• These findings provide insights into the substrate targeting and regulatory mechanisms of PP2Cs in stress response pathways.