S phase block following MEC1ATR inactivation occurs without severe dNTP depletion
Inactivation of Mec1, the budding yeast ATR, results in a permanent S phase arrest followed by chromosome breakage and cell death during G2/M. The S phase arrest is proposed to stem from a defect in Mec1-mediated degradation of Sml1, a conserved inhibitor of ribonucleotide reductase (RNR), causing a...
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The Company of Biologists
2015-12-01
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Series: | Biology Open |
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Online Access: | http://bio.biologists.org/content/4/12/1739 |
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author | Caroline Earp Samuel Rowbotham Gábor Merényi Andrei Chabes Rita S. Cha |
author_facet | Caroline Earp Samuel Rowbotham Gábor Merényi Andrei Chabes Rita S. Cha |
author_sort | Caroline Earp |
collection | DOAJ |
description | Inactivation of Mec1, the budding yeast ATR, results in a permanent S phase arrest followed by chromosome breakage and cell death during G2/M. The S phase arrest is proposed to stem from a defect in Mec1-mediated degradation of Sml1, a conserved inhibitor of ribonucleotide reductase (RNR), causing a severe depletion in cellular dNTP pools. Here, the casual link between the S phase arrest, Sml1, and dNTP-levels is examined using a temperature sensitive mec1 mutant. In addition to S phase arrest, thermal inactivation of Mec1 leads to constitutively high levels of Sml1 and an S phase arrest. Expression of a novel suppressor, GIS2, a conserved mRNA binding zinc finger protein, rescues the arrest without down-regulating Sml1 levels. The dNTP pool in mec1 is reduced by ∼17% and GIS2 expression restores it, but only partially, to ∼93% of a control. We infer that the permanent S phase block following Mec1 inactivation can be uncoupled from its role in Sml1 down-regulation. Furthermore, unexpectedly modest effects of mec1 and GIS2 on dNTP levels suggest that the S phase arrest is unlikely to result from a severe depletion of dNTP pool as assumed, but a heightened sensitivity to small changes in its availability. |
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id | doaj.art-8d91a02359ab4df6b3e3f909010b498c |
institution | Directory Open Access Journal |
issn | 2046-6390 |
language | English |
last_indexed | 2024-12-17T07:27:48Z |
publishDate | 2015-12-01 |
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spelling | doaj.art-8d91a02359ab4df6b3e3f909010b498c2022-12-21T21:58:35ZengThe Company of BiologistsBiology Open2046-63902015-12-014121739174310.1242/bio.015347015347S phase block following MEC1ATR inactivation occurs without severe dNTP depletionCaroline Earp0Samuel Rowbotham1Gábor Merényi2Andrei Chabes3Rita S. Cha4 Stem Cell Biology and Developmental Genetics, National Institute for Medical Research, MRC, London NW7 1AA, UK Stem Cell Biology and Developmental Genetics, National Institute for Medical Research, MRC, London NW7 1AA, UK Department of Medical Biochemistry and Biophysics, Umeå University, Umeå SE 901 87, Sweden Department of Medical Biochemistry and Biophysics, Umeå University, Umeå SE 901 87, Sweden Stem Cell Biology and Developmental Genetics, National Institute for Medical Research, MRC, London NW7 1AA, UK Inactivation of Mec1, the budding yeast ATR, results in a permanent S phase arrest followed by chromosome breakage and cell death during G2/M. The S phase arrest is proposed to stem from a defect in Mec1-mediated degradation of Sml1, a conserved inhibitor of ribonucleotide reductase (RNR), causing a severe depletion in cellular dNTP pools. Here, the casual link between the S phase arrest, Sml1, and dNTP-levels is examined using a temperature sensitive mec1 mutant. In addition to S phase arrest, thermal inactivation of Mec1 leads to constitutively high levels of Sml1 and an S phase arrest. Expression of a novel suppressor, GIS2, a conserved mRNA binding zinc finger protein, rescues the arrest without down-regulating Sml1 levels. The dNTP pool in mec1 is reduced by ∼17% and GIS2 expression restores it, but only partially, to ∼93% of a control. We infer that the permanent S phase block following Mec1 inactivation can be uncoupled from its role in Sml1 down-regulation. Furthermore, unexpectedly modest effects of mec1 and GIS2 on dNTP levels suggest that the S phase arrest is unlikely to result from a severe depletion of dNTP pool as assumed, but a heightened sensitivity to small changes in its availability.http://bio.biologists.org/content/4/12/1739Mec1ATRSml1RNRdNTPDNA replicationReplication arrest |
spellingShingle | Caroline Earp Samuel Rowbotham Gábor Merényi Andrei Chabes Rita S. Cha S phase block following MEC1ATR inactivation occurs without severe dNTP depletion Biology Open Mec1 ATR Sml1 RNR dNTP DNA replication Replication arrest |
title | S phase block following MEC1ATR inactivation occurs without severe dNTP depletion |
title_full | S phase block following MEC1ATR inactivation occurs without severe dNTP depletion |
title_fullStr | S phase block following MEC1ATR inactivation occurs without severe dNTP depletion |
title_full_unstemmed | S phase block following MEC1ATR inactivation occurs without severe dNTP depletion |
title_short | S phase block following MEC1ATR inactivation occurs without severe dNTP depletion |
title_sort | s phase block following mec1atr inactivation occurs without severe dntp depletion |
topic | Mec1 ATR Sml1 RNR dNTP DNA replication Replication arrest |
url | http://bio.biologists.org/content/4/12/1739 |
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