INOSITOL POLYPHOSPHATE PATHWAY REGULATES TPK1 EXPRESSION DURING HEAT STRESS

JARASLASKY, IVÁN; GAREIS, DANIELA; ORTOLÁ MARTÍNEZ, MARÍA CLARA; ROSSI, SILVIA; GALELLO, FIORELLA

Congreso; Reunión Anual Edición LIX SAIB 2023; 2023

SAIB

Yeasts are constantly challenged by environmental conditions and stressors. Saccharomyces cerevisiae uses different cellular mechanisms to adapt rapidly to thesechanges. One of them is the reorganization of expression patterns, where chromatin remodeling is crucial. It has been demonstrated that the inositol polyphosphatepathway plays a major role in the stress response and modulates the functions of several chromatin remodeling complexes. Protein kinase A (PKA) from S. cerevisiaecontrols a wide variety of biological processes and cellular functions in response to environmental changes. Yeast PKA is composed by two catalytic subunitsencoded by TPK1, TPK2 and TPK3 genes, and a dimer of regulatory subunits encoded by BCY1 gene. Previous research from our laboratory indicates that upon heatstress only TPK1 promoter activity is upregulated and TPK1 mRNA levels increase. TPK1 promoter has three positioned nucleosomes that are evicted during stress.This chromatin remodelling is SWI/SNF dependent. The purpose of this work is to obtain further knowledge in regards to the role of the inositol polyphosphatepathway on the expression regulation of yeast PKA subunits. Firstly, using β-galactosidase assays and qRT-PCR, we evaluated TPKs and BCY1 promoter activities andmRNA levels in null mutant strains for the inositol polyphosphate pathway. TPK1 promoter activity and mRNA levels decrease in the plc1, ipk2 and kcs1 strains.The activities of TPK2, TPK3 and BCY1 promoters present no changes in the null mutant strains evaluated, indicating that the effect of the inositol polyphosphatepathway is specific of TPK1 promoter. MNase protection assay shows that while plc1 and ipk2 strains exhibit alterations in chromatin remodelling of the TPK1promoter during heat stress, the ipk1 strain does not. Lastly, we investigated the recruitment of SWI/SNF complex to TPK1 promoter in the SNF2-TAP ipk2 strainusing ChIP assay. The absence of Ipk2 impairs the recruitment of SNF2-TAP to TPK1 promoter under heat stress conditions. Taken together, these results indicatethat the second messenger PP-IP4, whose synthesis depends on enzymes Plc1, Ipk2 and Kcs1, is involved in the transcriptional regulation TPK1 during heat stress.