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Essential and Checkpoint Functions of Budding Yeast ATM and ATR during Meiotic Prophase Are Facilitated by Differential Phosphorylation of a Meiotic Adaptor Protein, Hop1.

Penedos A, Johnson AL, Strong E, Goldman AS, Carballo JA, Cha RS - PLoS ONE (2015)

Bottom Line: A hallmark of the conserved ATM/ATR signalling is its ability to mediate a wide range of functions utilizing only a limited number of adaptors and effector kinases.In the absence of Dmc1, the phospho-S298 also promotes Mek1 hyper-activation necessary for implementing meiotic checkpoint arrest.Taking these observations together, we propose that the Hop1 phospho-T318 and phospho-S298 constitute key components of the Tel1/Mec1- based meiotic recombination surveillance (MRS) network and facilitate effective coupling of meiotic recombination and progression during both unperturbed and challenged meiosis.

View Article: PubMed Central - PubMed

Affiliation: Division of Stem Cell Biology and Developmental Genetics, MRC National Institute for Medical Research, London, NW7 1AA, United Kingdom.

ABSTRACT
A hallmark of the conserved ATM/ATR signalling is its ability to mediate a wide range of functions utilizing only a limited number of adaptors and effector kinases. During meiosis, Tel1 and Mec1, the budding yeast ATM and ATR, respectively, rely on a meiotic adaptor protein Hop1, a 53BP1/Rad9 functional analog, and its associated kinase Mek1, a CHK2/Rad53-paralog, to mediate multiple functions: control of the formation and repair of programmed meiotic DNA double strand breaks, enforcement of inter-homolog bias, regulation of meiotic progression, and implementation of checkpoint responses. Here, we present evidence that the multi-functionality of the Tel1/Mec1-to-Hop1/Mek1 signalling depends on stepwise activation of Mek1 that is mediated by Tel1/Mec1 phosphorylation of two specific residues within Hop1: phosphorylation at the threonine 318 (T318) ensures the transient basal level Mek1 activation required for viable spore formation during unperturbed meiosis. Phosphorylation at the serine 298 (S298) promotes stable Hop1-Mek1 interaction on chromosomes following the initial phospho-T318 mediated Mek1 recruitment. In the absence of Dmc1, the phospho-S298 also promotes Mek1 hyper-activation necessary for implementing meiotic checkpoint arrest. Taking these observations together, we propose that the Hop1 phospho-T318 and phospho-S298 constitute key components of the Tel1/Mec1- based meiotic recombination surveillance (MRS) network and facilitate effective coupling of meiotic recombination and progression during both unperturbed and challenged meiosis.

No MeSH data available.


Related in: MedlinePlus

Genetic interaction among hop1-S298A, dmc1Δ, and hed1Δ.A. PFGE/Southern analysis of ChrIII was performed on samples prepared from a hop1-S298A dmc1Δ or HOP1 dmc1Δ strain. Positions of the full length (FL) and DSBs are indicated on the right side of the gel. Positions of the CHA1 probe (P) and centromere (filled circle) are indicated on the left side of the gel. B. Spore viability of homozygous diploid strains of the indicated genotypes at 23°C. For each genotype, at least 80 spores were analysed.
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pone.0134297.g002: Genetic interaction among hop1-S298A, dmc1Δ, and hed1Δ.A. PFGE/Southern analysis of ChrIII was performed on samples prepared from a hop1-S298A dmc1Δ or HOP1 dmc1Δ strain. Positions of the full length (FL) and DSBs are indicated on the right side of the gel. Positions of the CHA1 probe (P) and centromere (filled circle) are indicated on the left side of the gel. B. Spore viability of homozygous diploid strains of the indicated genotypes at 23°C. For each genotype, at least 80 spores were analysed.

Mentions: dmc1Δ-mediated meiotic arrest is triggered by accumulation of unrepaired meiotic DSBs, which activates the checkpoint function of Tel1/Mec1 [19]. The arrest can be bypassed by either the mutations that permit meiotic progression in the presence of unrepaired breaks (e.g. mec1-1, rad24Δ, or rad17Δ) or allowing Rad51 mediated DSB repair (e.g. hed1Δ, hop1-T318A or mek1Δ) [5, 6, 22–24]. Rad51 is the other budding yeast RecA homolog, whose recombinase function becomes inhibited during meiosis by its meiosis-specific inhibitor Hed1 [24, 25]. To test which of the two mechanisms was responsible for the hop1-S298A alleviation of dmc1Δ meiotic arrest, we examined the status of meiotic DSBs in a hop1-S298A dmc1Δ strain. Results showed that breaks did not accumulate in the double mutant (Fig 2A). Since Spo11 catalysis initiates normally in the absence of the Hop1 phospho-S298 [6], the latter suggests that the hop1-S298A alleviation of dmc1Δ arrest is attributable to Rad51-mediated recombination, circumventing accumulation of unrepaired DSBs.


Essential and Checkpoint Functions of Budding Yeast ATM and ATR during Meiotic Prophase Are Facilitated by Differential Phosphorylation of a Meiotic Adaptor Protein, Hop1.

Penedos A, Johnson AL, Strong E, Goldman AS, Carballo JA, Cha RS - PLoS ONE (2015)

Genetic interaction among hop1-S298A, dmc1Δ, and hed1Δ.A. PFGE/Southern analysis of ChrIII was performed on samples prepared from a hop1-S298A dmc1Δ or HOP1 dmc1Δ strain. Positions of the full length (FL) and DSBs are indicated on the right side of the gel. Positions of the CHA1 probe (P) and centromere (filled circle) are indicated on the left side of the gel. B. Spore viability of homozygous diploid strains of the indicated genotypes at 23°C. For each genotype, at least 80 spores were analysed.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520594&req=5

pone.0134297.g002: Genetic interaction among hop1-S298A, dmc1Δ, and hed1Δ.A. PFGE/Southern analysis of ChrIII was performed on samples prepared from a hop1-S298A dmc1Δ or HOP1 dmc1Δ strain. Positions of the full length (FL) and DSBs are indicated on the right side of the gel. Positions of the CHA1 probe (P) and centromere (filled circle) are indicated on the left side of the gel. B. Spore viability of homozygous diploid strains of the indicated genotypes at 23°C. For each genotype, at least 80 spores were analysed.
Mentions: dmc1Δ-mediated meiotic arrest is triggered by accumulation of unrepaired meiotic DSBs, which activates the checkpoint function of Tel1/Mec1 [19]. The arrest can be bypassed by either the mutations that permit meiotic progression in the presence of unrepaired breaks (e.g. mec1-1, rad24Δ, or rad17Δ) or allowing Rad51 mediated DSB repair (e.g. hed1Δ, hop1-T318A or mek1Δ) [5, 6, 22–24]. Rad51 is the other budding yeast RecA homolog, whose recombinase function becomes inhibited during meiosis by its meiosis-specific inhibitor Hed1 [24, 25]. To test which of the two mechanisms was responsible for the hop1-S298A alleviation of dmc1Δ meiotic arrest, we examined the status of meiotic DSBs in a hop1-S298A dmc1Δ strain. Results showed that breaks did not accumulate in the double mutant (Fig 2A). Since Spo11 catalysis initiates normally in the absence of the Hop1 phospho-S298 [6], the latter suggests that the hop1-S298A alleviation of dmc1Δ arrest is attributable to Rad51-mediated recombination, circumventing accumulation of unrepaired DSBs.

Bottom Line: A hallmark of the conserved ATM/ATR signalling is its ability to mediate a wide range of functions utilizing only a limited number of adaptors and effector kinases.In the absence of Dmc1, the phospho-S298 also promotes Mek1 hyper-activation necessary for implementing meiotic checkpoint arrest.Taking these observations together, we propose that the Hop1 phospho-T318 and phospho-S298 constitute key components of the Tel1/Mec1- based meiotic recombination surveillance (MRS) network and facilitate effective coupling of meiotic recombination and progression during both unperturbed and challenged meiosis.

View Article: PubMed Central - PubMed

Affiliation: Division of Stem Cell Biology and Developmental Genetics, MRC National Institute for Medical Research, London, NW7 1AA, United Kingdom.

ABSTRACT
A hallmark of the conserved ATM/ATR signalling is its ability to mediate a wide range of functions utilizing only a limited number of adaptors and effector kinases. During meiosis, Tel1 and Mec1, the budding yeast ATM and ATR, respectively, rely on a meiotic adaptor protein Hop1, a 53BP1/Rad9 functional analog, and its associated kinase Mek1, a CHK2/Rad53-paralog, to mediate multiple functions: control of the formation and repair of programmed meiotic DNA double strand breaks, enforcement of inter-homolog bias, regulation of meiotic progression, and implementation of checkpoint responses. Here, we present evidence that the multi-functionality of the Tel1/Mec1-to-Hop1/Mek1 signalling depends on stepwise activation of Mek1 that is mediated by Tel1/Mec1 phosphorylation of two specific residues within Hop1: phosphorylation at the threonine 318 (T318) ensures the transient basal level Mek1 activation required for viable spore formation during unperturbed meiosis. Phosphorylation at the serine 298 (S298) promotes stable Hop1-Mek1 interaction on chromosomes following the initial phospho-T318 mediated Mek1 recruitment. In the absence of Dmc1, the phospho-S298 also promotes Mek1 hyper-activation necessary for implementing meiotic checkpoint arrest. Taking these observations together, we propose that the Hop1 phospho-T318 and phospho-S298 constitute key components of the Tel1/Mec1- based meiotic recombination surveillance (MRS) network and facilitate effective coupling of meiotic recombination and progression during both unperturbed and challenged meiosis.

No MeSH data available.


Related in: MedlinePlus