1
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Basier C, Nurse P. TOR regulates variability of protein synthesis rates. EMBO J 2024; 43:1618-1633. [PMID: 38499788 PMCID: PMC11021518 DOI: 10.1038/s44318-024-00075-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 03/20/2024] Open
Abstract
Cellular processes are subject to inherent variability, but the extent to which cells can regulate this variability has received little investigation. Here, we explore the characteristics of the rate of cellular protein synthesis in single cells of the eukaryote fission yeast. Strikingly, this rate is highly variable despite protein synthesis being dependent on hundreds of reactions which might be expected to average out at the overall cellular level. The rate is variable over short time scales, and exhibits homoeostatic behaviour at the population level. Cells can regulate the level of variability through processes involving the TOR pathway, suggesting there is an optimal level of variability conferring a selective advantage. While this could be an example of bet-hedging, but we propose an alternative explanation: regulated 'loose' control of complex processes of overall cellular metabolism such as protein synthesis, may lead to this variability. This could ensure cells are fluid in control and agile in response to changing conditions, and may constitute a novel organisational principle of complex metabolic cellular systems.
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Affiliation(s)
- Clovis Basier
- Cell Cycle Laboratory, The Francis Crick Institute, London, NW1 1AT, UK.
| | - Paul Nurse
- Cell Cycle Laboratory, The Francis Crick Institute, London, NW1 1AT, UK
- Laboratory of Yeast Genetics and Cell Biology, Rockefeller University, New York, NY, 10065, USA
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2
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Abstract
Elongator is required for the synthesis of the mcm(5)s(2) modification found on tRNAs recognizing AA-ending codons. In order to obtain a global picture of the role of Elongator in translation, we used reverse protein arrays to screen the fission yeast proteome for translation defects. Unexpectedly, this revealed that Elongator inactivation mainly affected three specific functional groups including proteins implicated in cell division. The absence of Elongator results in a delay in mitosis onset and cytokinesis defects. We demonstrate that the kinase Cdr2, which is a central regulator of mitosis and cytokinesis, is under translational control by Elongator due to the Lysine codon usage bias of the cdr2 coding sequence. These findings uncover a mechanism by which the codon usage, coupled to tRNA modifications, fundamentally contributes to gene expression and cellular functions.
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3
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Sakai T. Cdk inhibitor ste9p/srw1p is involved in response to protein synthesis inhibition in fission yeast. Biochem Biophys Res Commun 2004; 315:984-90. [PMID: 14985109 DOI: 10.1016/j.bbrc.2004.01.148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Indexed: 10/26/2022]
Abstract
It remains unknown whether the cell cycle system responds properly to protein synthesis inhibition. In this paper I report finding in Schizosaccharomyces pombe that partially deleted elongation factor 3 genes rescue various mitotic catastrophe mutants depending on deltaste9 in a dominant-negative manner. In response to protein synthesis inhibitors, deltaste9 and some other mutants delay halting the cell cycle at G2-M and the combined cdc2-M26 deltaste9 mutant greatly loses viability. It is suggested that cell cycle be positively controlled in an ste9-dependent manner before essential factors for viability and other important functions are exhausted when protein synthesis is inhibited.
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Affiliation(s)
- Takaaki Sakai
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
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4
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Chua G, Lingner C, Frazer C, Young PG. The sal3(+) gene encodes an importin-beta implicated in the nuclear import of Cdc25 in Schizosaccharomyces pombe. Genetics 2002; 162:689-703. [PMID: 12399381 PMCID: PMC1462273 DOI: 10.1093/genetics/162.2.689] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In Schizosaccharomyces pombe, the nuclear accumulation of Cdc25 peaks in G2 and is necessary for the proper timing of mitotic entry. Here, we identify the sal3(+) gene product as an importin-beta homolog that participates in the nuclear import of Cdc25. Loss of sal3(+) results in a cell cycle delay, failure to undergo G1 arrest under nitrogen-starvation conditions, and mislocalization of Cdc25 to the cytosol. Fusion of an exogenous classical nuclear localization sequence (cNLS) to Cdc25 restores its nuclear accumulation in a sal3 disruptant and suppresses the sal3 mutant phenotypes. In addition, we show that enhanced nuclear localization of Cdc25 at endogenous levels of expression advances the onset of mitosis. These results demonstrate that the nuclear translocation of Cdc25 is important for the timing of mitotic entry and that Sal3 plays an important role in this process.
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Affiliation(s)
- Gordon Chua
- Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada
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5
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Suda M, Yamada S, Toda T, Miyakawa T, Hirata D. Regulation of Wee1 kinase in response to protein synthesis inhibition. FEBS Lett 2000; 486:305-9. [PMID: 11119724 DOI: 10.1016/s0014-5793(00)02299-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
To investigate the mechanism coupling growth (protein synthesis) with cell division, we examined the relationship between the tyrosine kinase Wee1 that inhibits Cdc2-Cdc13 mitosis-inducing kinase by phosphorylating it, and protein synthesis inhibition in fission yeast. The wee1-50 mutant showed supersensitivity to protein synthesis inhibitor, cycloheximide. Wee1 was essential for the G(2) delay upon a partial inhibition of protein synthesis. Indeed, the protein synthesis inhibition caused an increase in the Wee1 protein by the Sty1/Spc1 MAPK-dependent transcriptional and the Sty1/Spc1 MAPK-independent post-transcriptional regulations. Further, the results indicated that the post-transcriptional regulation is important for the G(2) delay.
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Affiliation(s)
- M Suda
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Japan
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6
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Daga RR, Jimenez J. Translational control of the cdc25 cell cycle phosphatase: a molecular mechanism coupling mitosis to cell growth. J Cell Sci 1999; 112 Pt 18:3137-46. [PMID: 10462529 DOI: 10.1242/jcs.112.18.3137] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The eukaryotic translation initiation factor 4A (eIF4A) is an RNA helicase required for translation initiation of eukaryotic mRNAs. By engineering fission yeast mutants with diminished eIF4A activity, we have found that translation of cdc25 mRNAs (a dosage-dependent activator of mitosis in all eukaryotic cells) is particularly sensitive to limitations of protein synthesis mediated by limited eIF4A activity. Genetic and biochemical analysis indicated that a rate-limited translation initiation of cdc25 mRNAs, exerted throughout its unusual 5′ untranslated leader, acts as a molecular sensor to ensure that a minimum cell mass (protein synthesis) is attained before mitosis occurs. The Cdc13 cyclin B is also among the limited pool of proteins whose translation is sensitive to reduced translation initiation activity. Interestingly, the 5′ leader sequences of cdc25 and cdc13 mRNAs have conserved features which are unusual in other yeast mRNAs, suggesting that common mechanisms operate in the expression of these two key mitotic activators at the translational level.
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Affiliation(s)
- R R Daga
- Unidad de Genética, Facultad de Ciencias, Universidad de Málaga, Campus Universitario de Teatinos, Spain
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7
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Grallert A, Grallert B, Ribar B, Sipiczki M. Coordination of initiation of nuclear division and initiation of cell division in Schizosaccharomyces pombe: genetic interactions of mutations. J Bacteriol 1998; 180:892-900. [PMID: 9473044 PMCID: PMC106969 DOI: 10.1128/jb.180.4.892-900.1998] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
sep1+ encodes a Schizosaccharomyces pombe homolog of the HNF-3/forkhead family of the tissue-specific and developmental gene regulators identified in higher eukaryotes. Its mutant allele sep1-1 causes a defect in cytokinesis and confers a mycelial morphology. Here we report on genetic interactions of sep1-1 with the M-phase initiation mutations wee1-, cdc2-1w, and cdc25-22. The double mutants sep1-1 wee1- and sep1-1 cdc2-1w form dikaryon cells at high frequency, which is due to nuclear division in the absence of cell division. The dikaryosis is reversible and suppressible by cdc25-22. We propose that the genes wee1+, cdc2+, cdc25+, and sep1+ form a regulatory link between the initiation of mitosis and the initiation of cell division.
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Affiliation(s)
- A Grallert
- Department of Genetics, University of Debrecen, Hungary
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8
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Münch T, Sonnleitner B, Fiechter A. The decisive role of the Saccharomyces cerevisiae cell cycle behaviour for dynamic growth characterization. J Biotechnol 1992; 22:329-51. [PMID: 1367988 DOI: 10.1016/0168-1656(92)90150-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The dynamic behaviour of the cell cycle and the physiology of Saccharomyces cerevisiae was monitored in transient experiments. Frequent flow cytometric analyses of the DNA (nuclear phase state) and the cell size enabled us to characterize the proliferation properties of yeast cells under well controlled and undisturbed cultivation conditions. Preliminarily, the correlation between flow cytometric light scattering measurements and the cell size was attested for yeasts. These flow cytometric results are compared with the physiological behaviour of the culture that was detected by high resolution on-line analyses and off-line measurements. The presented results focus on the importance of the yeast cell cycle behaviour for the dynamic growth characterization. Any kind of transients in yeast cultures induced partial synchronization. The characteristics and the time course of the yeast cell cycle were found to be strongly dependent on the physiological environment.
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Affiliation(s)
- T Münch
- Department for Biotechnology, Swiss Federal Institute of Technology, ETH Zürich Hönggerberg
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9
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Abstract
As an aid to the fission yeast genome project, we describe a database for Schizosaccharomyces pombe consisting of both genetic and physical information. As presented, it is therefore both an updated gene list of all the nuclear genes of the fission yeast, and provides an estimate of the physical distance between two mapped genes. Additionally, a field indicates whether the sequence of the gene is available. Currently, sequence information is available for 135 of the 501 known genes.
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Affiliation(s)
- G G Lennon
- Biomed. Div. L-452, Lawrence Livermore National Laboratory, Livermore, CA 94550
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10
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Chapter 1 Synthesis and Function of Modified Nucleosides in tRNA. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0301-4770(08)61487-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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11
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Booher R, Beach D. Involvement of a type 1 protein phosphatase encoded by bws1+ in fission yeast mitotic control. Cell 1989; 57:1009-16. [PMID: 2544292 DOI: 10.1016/0092-8674(89)90339-5] [Citation(s) in RCA: 157] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Fission yeast cdc25+ and wee1+ interact genetically with cdc2+ in the regulation of cell division, respectively as a mitotic activator and inhibitor. cdc25+ is normally essential for mitosis, but this requirement is alleviated in a loss-of-function wee1 mutant background. A plasmid-borne sequence, other than wee1+, that causes a cdc25ts wee1- double mutant to revert to a temperature-sensitive cdc phenotype has been isolated. The gene carried by this plasmid is called bws1+ (for bypass of wee suppression). bws1+ also bypasses the ability of alleles of cdc2 that confer a wee phenotype (cdc2w) to suppress loss-of-function cdc25 mutants. The nucleotide sequence of bws1+ shows that the predicted protein shares 81% amino acid identity with the catalytic subunit of mammalian type 1 protein phosphatase. Thus a genetic screen that might have yielded a protein kinase (wee1+) uncovered a phosphatase that also appears to be involved in the pathway of mitotic control.
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Affiliation(s)
- R Booher
- Cold Spring Harbor Laboratory, New York 11724
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12
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Russell P, Nurse P. The mitotic inducer nim1+ functions in a regulatory network of protein kinase homologs controlling the initiation of mitosis. Cell 1987; 49:569-76. [PMID: 3453113 DOI: 10.1016/0092-8674(87)90459-4] [Citation(s) in RCA: 265] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The newly discovered fission yeast mitotic control element nim1+ (new inducer of mitosis) is the first dose-dependent mitotic inducer identified as a protein kinase homolog. Increased nim1+ expression rescues mutants lacking the mitotic inducer cdc25+ and advances cells into mitosis at a reduced cell size; loss of nim1+ delays mitosis until cells have grown to a larger size. The nim1+ gene potentially encodes a 50 kd protein that contains the consensus sequences of protein kinases. Genetic evidence indicates that nim1+ is a negative regulator of the wee1+ mitotic inhibitor, another protein kinase homolog. The combined mitotic induction activities of nim1+ and cdc25+ counteract the wee1+ mitotic inhibitor in a regulatory network that appears also to involve the cdc2+ protein kinase, which is required for mitosis.
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13
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Ogden JE, Fantes PA. Isolation of a novel type of mutation in the mitotic control of Schizosaccharomyces pombe whose phenotypic expression is dependent on the genetic background and nutritional environment. Curr Genet 1986; 10:509-14. [PMID: 3442828 DOI: 10.1007/bf00447384] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The major cell cycle control in the fission yeast Schizosaccharomyces pombe acts at entry to mitosis, and involves three previously identified genes cdc2, cdc25 and wee1. The presence of a wee1 mutation phenotypically suppresses cdc25 mutations. This paper describes the isolation and subsequent analysis of a strain in which the suppression is reversed by the presence of a new mutation, designated win1.1. The mutation causes a slight increase in cell size at division in most genetic backgrounds. However, when combined with a wee1 mutation and cdc25.22, the win1.1 mutation interacts strongly to generate a novel phenotype: cells are phenotypically cdc during growth on minimal medium but cdc+ when cultured on complex medium. The win1 locus is unlinked to previously identified genes involved in mitosis.
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Affiliation(s)
- J E Ogden
- Department of Zoology, University of Edinburgh, UK
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