"CTP synthase (CTPS), a metabolic enzyme responsible for the de novo synthesis of CTP, can form filamentous structures termed cytoophidia, which are evolutionarily conserved from bacteria to humans."

"ubiquitination is important for the maintenance of the CTPS filamentous structure in fission yeast"

"We have identified proteins which are in complex with CTPS, including specific ubiquitination regulators which significantly affect CTPS filamentation, and mapped probable ubiquitination targets on CTPS."

"Furthermore, we discovered that a cohort of deubiquitinating enzymes is important for the regulation of cytoophidium's filamentous morphology."

"The essential metabolic enzyme CTP synthase (CTPS)2 is critical for the de novo pathway and catalyzes the ATP-dependent transfer of nitrogen from glutamine to UTP, forming glutamate and CTP"

"The average length of cytoophidia was significantly reduced from 2.075 μm (S.D.: ±0.063 μm) in untreated cells to 1.21 μm (S.D.: ±0.064 μm) and 1.25 μm (S.D.: ±0.062 μm) after treatment with rapamycin and everolimus, a reduction of 41.8% (p < 0.0001) and 40% (p < 0.001), respectively"

"In contrast to mammalian systems, not only TORC1 but both TORC1 and TORC2 sub-complexes participate in the regulation of Cts1 cytoophidia formation"

"We showed that the regulation is mediated by S6K/AGC kinases that act downstream of both TORC1 and TORC2 complexes, contrary to mammalian cells, in which only mTOR1/S6K1 has been shown to play a role"

"deletion of Crf1 transcriptional co-repressor shows 95.3% reduction in cells containing cytoophidia and ∼50% reduction in their average length... Crf1 is a transcriptional corepressor for ribosomal proteins via TOR signaling"

"In S. pombe, reduction of filamentation did not significantly change the CTPS enzymatic activity in the TOR subunit knockout mutants, while it reduced it in the TORC2 downstream effector mutants. This suggests that in the case of Crf1 and Gad8 mutants, CTPS polymerization increases the enzyme's activity"

"is the sole essential CTPS enzyme catalyzing ATP-dependent UTP→CTP conversion, using glutamine-derived ammonia and regulated by GTP activation and CTP feedback inhibition"

"fission yeast as a model with **a single CTPS gene**, encoded at the **cts1** locus"

"an N-terminal **synthase (ammonia ligase) domain** that binds ATP/UTP and performs the phosphorylation/amination chemistry, and"

"cytoophidia that are **highly abundant during logarithmic growth** (reported **>90%** of cells) and largely **disappear in stationary phase**"

"Filament integrity is functionally linked to cell-cycle control (G2 length), cell size, and gene expression (slm9)"

"post-translational regulation associated with **ubiquitin binding** and **ubiquitin-mediated degradation**"

"Cytidine triphosphate (CTP) is a rate-limiting enzyme that catalyzes the ATP-dependent conversion of UTP to CTP"

"S. pombe only harbors one CTPS isoform encoded by a single locus cts1 on chromosome I"

"cytoophidia were present in over 90% of fission yeast cells (Figure 1A,C) and subsequently disappeared during the stationary phase"

"The CTPS H359A mutant fission yeast was viable but did not form cytoophidia"

"the gene expression levels of cdc25, cdr1, cdc13, fin1, blt1, slm9, pop3, tor1, and tor2 were decreased compared with those in the Cts1 strain"

"overexpression of slm9 alleviates cell cycle prolongation at the G2 phase caused by Cts1-H359A mutation"