Activación de la MAPK de Saccharomyces cerevisiae SLT2 : mecanismo molecular e implicación en el fenotipo de multigemación de células carentes de la fosfatasa PTC1

Abstract

Mitogen-Activated Protein Kinase (MAPK) pathways plays a fundamental role inregulating essential processes in eukaryotic cells. Slt2, the MAPK of the Saccharomyces cerevisae Cell Wall Integrity (CWI) pathway, is necessary for the compensatory response against cell wall damage. MAPK full activation requires dual phosphorylation at both the threonine and tyrosine of the conserved TXY motif within the activation loop (T190-EY192in Slt2). However, in many cases, monophosphorylated forms have different roles that remain unknown. The protein phosphatase Ptc1 regulates signaling through the CWI pathway, as well as a wide range of cellular functions. Hence, cells lacking Ptc1 exhibit Slt2 hyperphosphorylation and cell separation defects, among others. Cell separation requires Ace2 entry to daughter cell nuclei and subsequent expression of genes such as CTS1 and DSE1. Deletion of MKK1, encoding the main MAPKK acting onSlt2, abolishes many of the alterations displayed by ptc1Δ cells. Nevertheless, the regulatory mechanisms underlying these alterations are still unknown...