Constitutively Active 1 RAS in S. Pombe Causes Persistent Cdc42 Signalling But Only Transient MAPK Activation

Kelsall, Emma J.; Vértesy, Ábel; Straatman, Kees R; Tariq, Mishal; Gadea, Raquel; Parmar, Chandni; Schreiber, G; Randhawa, Shubhchintan; Dominguez, Cyril; Klipp, Edda; Tanaka, Kayoko

doi:10.2139/ssrn.3237000

Cited by 1 publication

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“…Second, because of the use of the split fus1 opto allele for synchronization during cell-cell fusion, we should be careful about interpretation of phosphorylation events on Fus1 and accessory proteins, as these may not represent native changes at the fusion site. Nevertheless, the few phosphorylation events that were expected (for instance that of the MAPK Spk1 active site; (Kelsall et al, 2019)) or independently confirmed here (Rps6) validate the approach and suggest that identified phosphorylation events also occur in wildtype strains.…”

Section: Discussionsupporting

confidence: 74%

“…Amongst sites whose phosphorylation increases, we identified several expected sites on proteins necessary for mating (coloured in Fig 3G), including in the pheromone MAPK-Spk1 active site (T199 and Y201) (Kelsall et al, 2019) and on the C-terminal tails of pheromone receptors, likely to promote their internalisation (T325 on Mam2 and S346, S349 on Map3). Phosphorylation of the transcription factor Ste11 also significantly increased after 45 min, though surprisingly not at the previously mapped MAPK-Spk1 target sites (Kjaerulff et al, 2005), but at T173 shown to be phosphorylated by Pat1 kinase (Li and McLeod, 1996).…”

Section: Resultsmentioning

confidence: 99%

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TORC1 reactivation by pheromone signaling revealed by phosphoproteomics of fission yeast sexual reproduction

Bérard,

Merlini,

Martin

2024

Preprint

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Starvation, which is associated with inactivation of the growth-promoting TOR complex 1 (TORC1), is a strong environmental signal for cell differentiation. In the fission yeastSchizosaccharomyces pombe, nitrogen starvation has distinct physiological consequences depending on the presence of mating partners. In their absence, cells enter quiescence, and TORC1 inactivation prolongs their life. In presence of compatible mates, TORC1 inactivation is essential for sexual differentiation. Gametes engage in paracrine pheromone signaling, grow towards each other, fuse to form the diploid zygote, and form resistant, haploid spore progenies. To understand the signaling changes in the proteome and phospho-proteome during sexual reproduction, we developed cell synchronization strategies and present (phospho-)proteomic datasets that dissect pheromone from starvation signals over the sexual differentiation and cell-cell fusion processes. Unexpectedly, these datasets reveal phosphorylation of ribosomal protein S6 during sexual development, which we establish requires TORC1 activity. We demonstrate that TORC1 is re-activated by pheromone signaling, in a manner that does not require autophagy. Mutants with low TORC1 re-activation exhibit compromised mating and poorly viable spores. Thus, while inactivated to initiate the mating process, TORC1 is reactivated by pheromone signaling in starved cells to support sexual reproduction.

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Section: Discussionsupporting

confidence: 74%