The Rim15-endosulfine-[PP2A.sup.Cdc55] signalling module regulates entry into gametogenesis and quiescence via distinct mechanisms in budding yeast

• Published in: PLoS genetics Vol. 10; no. 6
• Main Authors: Sarkar, Sourav, Dalgaard, Jacob Z, Millar, Jonathan B.A, Arumugam, Prakash
• Format: Journal Article
• Language: English
• Published: Public Library of Science 01.06.2014
• Subjects: Amphibians; DNA replication; Gametogenesis; Genetic aspects; Physiological aspects; Protein research
• ISSN: 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1004456

Quiescence and gametogenesis represent two distinct survival strategies in response to nutrient starvation in budding yeast. Precisely how environmental signals are sensed by yeast cells to trigger quiescence and gametogenesis is not fully understood. A conserved signalling module consisting of Greatwall kinase, Endosulfine and Protein Phosphatase [PP2A.sup.Cdc55] proteins regulates entry into mitosis in Xenopus egg extracts and meiotic maturation in flies. We report here that an analogous signalling module consisting of the serine-threonine kinase Rim15, the Endosulfines Igol and Igo2 and the Protein Phosphatase [PP2A.sup.Cdc55], regulates entry into both quiescence and gametogenesis in budding yeast. [PP2A.sup.Cdc55] inhibits entry into gametogenesis and quiescence. Rim15 promotes entry into gametogenesis and quiescence by converting Igo1 into an inhibitor of [PP2A.sup.Cdc55] by phosphorylating at a conserved serine residue. Moreover, we show that the Rim15-Endosulfine-[PP2A.sup.Cdc55] pathway regulates entry into quiescence and gametogenesis by distinct mechanisms. In addition, we show that Igo1 and Igo2 are required for pre-meiotic autophagy but the lack of pre-meiotic autophagy is insufficient to explain the sporulation defect of igo1Δ igo2Δ cells. We propose that the Rim15-Endosulfine-[PP2A.sup.Cdc55] signalling module triggers entry into quiescence and gametogenesis by regulating dephosphorylation of distinct substrates.