Limits...
Separable Crossover-Promoting and Crossover-Constraining Aspects of Zip1 Activity during Budding Yeast Meiosis.

Voelkel-Meiman K, Johnston C, Thappeta Y, Subramanian VV, Hochwagen A, MacQueen AJ - PLoS Genet. (2015)

Bottom Line: While stable, full-length SC does not assemble in S. cerevisiae cells expressing K. lactis ZIP1, aggregates of K. lactis Zip1 displayed by S. cerevisiae meiotic nuclei are decorated with SC-associated proteins, and K. lactis Zip1 promotes the SUMOylation of the SC central element protein Ecm11, suggesting that K. lactis Zip1 functionally interfaces with components of the S. cerevisiae synapsis machinery.This separation-of-function version of Zip1 thus reveals that neither assembled SC nor MutSγ is required for Mlh3-dependent crossover formation per se in budding yeast.Our data suggest that features of S. cerevisiae Zip1 or of the assembled SC in S. cerevisiae normally constrain MutLγ to preferentially promote resolution of MutSγ-associated recombination intermediates.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology and Biochemistry, Wesleyan University, Middletown, Connecticut, United States of America.

ABSTRACT
Accurate chromosome segregation during meiosis relies on the presence of crossover events distributed among all chromosomes. MutSγ and MutLγ homologs (Msh4/5 and Mlh1/3) facilitate the formation of a prominent group of meiotic crossovers that mature within the context of an elaborate chromosomal structure called the synaptonemal complex (SC). SC proteins are required for intermediate steps in the formation of MutSγ-MutLγ crossovers, but whether the assembled SC structure per se is required for MutSγ-MutLγ-dependent crossover recombination events is unknown. Here we describe an interspecies complementation experiment that reveals that the mature SC is dispensable for the formation of Mlh3-dependent crossovers in budding yeast. Zip1 forms a major structural component of the budding yeast SC, and is also required for MutSγ and MutLγ-dependent crossover formation. Kluyveromyces lactis ZIP1 expressed in place of Saccharomyces cerevisiae ZIP1 in S. cerevisiae cells fails to support SC assembly (synapsis) but promotes wild-type crossover levels in those nuclei that progress to form spores. While stable, full-length SC does not assemble in S. cerevisiae cells expressing K. lactis ZIP1, aggregates of K. lactis Zip1 displayed by S. cerevisiae meiotic nuclei are decorated with SC-associated proteins, and K. lactis Zip1 promotes the SUMOylation of the SC central element protein Ecm11, suggesting that K. lactis Zip1 functionally interfaces with components of the S. cerevisiae synapsis machinery. Moreover, K. lactis Zip1-mediated crossovers rely on S. cerevisiae synapsis initiation proteins Zip3, Zip4, Spo16, as well as the Mlh3 protein, as do the crossovers mediated by S. cerevisiae Zip1. Surprisingly, however, K. lactis Zip1-mediated crossovers are largely Msh4/Msh5 (MutSγ)-independent. This separation-of-function version of Zip1 thus reveals that neither assembled SC nor MutSγ is required for Mlh3-dependent crossover formation per se in budding yeast. Our data suggest that features of S. cerevisiae Zip1 or of the assembled SC in S. cerevisiae normally constrain MutLγ to preferentially promote resolution of MutSγ-associated recombination intermediates.

No MeSH data available.


One model to explain the constrained relationship between MutSγ, SIC/Zip1-associated JMs, and MutLγ proteins and how K. l. Zip1 might bypass the constraint.Cartoons depict potential pathways for SC protein-MutSγ-MutLγ associated crossovers in budding yeast. At left is depicted S. cerevisiae expressing S. c. ZIP1, while at right is depicted S. cerevisiae expressing K. l. ZIP1. In these models, Zip1 maintains a pro-crossover function along with other SIC proteins and Msh4/Msh5, upstream of stabilized dHJs. Both S. c. Zip1 and K. l. Zip1 collaborate with other SIC proteins and Msh4/Msh5 to promote the establishment of stable JMs. In this model, S. c. Zip1 also has an anti-crossover activity that Msh4/Msh5 normally counters (left cartoon). This anti-crossover activity might be an intrinsic feature of the Zip1 protein or perhaps is an activity coming from SC formation. An antagonistic relationship between Msh4/Msh5 and S. c. Zip1 constrains Zip1-mediated, MutLγ-associated resolvase activity to act exclusively on MutSγ-associated recombination intermediates. In the context of S. cerevisiae cells expressing K. l. ZIP1 (right cartoon), K. l. Zip1 retains the pro-crossover activity but lacks the anti-crossover activity of S. c. Zip1, rendering MutSγ dispensable for MutLγ-dependent crossover recombination. Since K. l. Zip1 uncouples Mlh3-mediated crossover formation from both SC assembly and from a reliance on Msh4, we are drawn to the possibility that SC assembly normally constrains Zip1 crossovers–ensuring that they occur successfully only on Msh4-associated intermediates. We emphasize that the anti-crossover aspects of Zip1 activity could either be an action that destabilizes JM structures or one that prevents the accessibility of JM structures to MutLγ and other resolvase proteins.
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pgen.1005335.g009: One model to explain the constrained relationship between MutSγ, SIC/Zip1-associated JMs, and MutLγ proteins and how K. l. Zip1 might bypass the constraint.Cartoons depict potential pathways for SC protein-MutSγ-MutLγ associated crossovers in budding yeast. At left is depicted S. cerevisiae expressing S. c. ZIP1, while at right is depicted S. cerevisiae expressing K. l. ZIP1. In these models, Zip1 maintains a pro-crossover function along with other SIC proteins and Msh4/Msh5, upstream of stabilized dHJs. Both S. c. Zip1 and K. l. Zip1 collaborate with other SIC proteins and Msh4/Msh5 to promote the establishment of stable JMs. In this model, S. c. Zip1 also has an anti-crossover activity that Msh4/Msh5 normally counters (left cartoon). This anti-crossover activity might be an intrinsic feature of the Zip1 protein or perhaps is an activity coming from SC formation. An antagonistic relationship between Msh4/Msh5 and S. c. Zip1 constrains Zip1-mediated, MutLγ-associated resolvase activity to act exclusively on MutSγ-associated recombination intermediates. In the context of S. cerevisiae cells expressing K. l. ZIP1 (right cartoon), K. l. Zip1 retains the pro-crossover activity but lacks the anti-crossover activity of S. c. Zip1, rendering MutSγ dispensable for MutLγ-dependent crossover recombination. Since K. l. Zip1 uncouples Mlh3-mediated crossover formation from both SC assembly and from a reliance on Msh4, we are drawn to the possibility that SC assembly normally constrains Zip1 crossovers–ensuring that they occur successfully only on Msh4-associated intermediates. We emphasize that the anti-crossover aspects of Zip1 activity could either be an action that destabilizes JM structures or one that prevents the accessibility of JM structures to MutLγ and other resolvase proteins.

Mentions: On the other hand, Fig 9 presents an alternative model to explain both the mechanism that normally constrains MutLγ activity to target MutSγ-associated recombination intermediates in S. cerevisiae and how K. l. Zip1 bypasses this constraint. In our alternative model, we propose that S. c. Zip1 is normally associated with both pro-crossover and anti-crossover activities, and that Msh4/Msh5 counters the anti-crossover activity of Zip1 at JMs. A possible anti-crossover aspect of Zip1 activity could be an action that destabilizes dHJ structures, or one that prevents the accessibility of dHJ structures to MutLγ-associated resolvase activity. The presence of MutSγ at JMs might protect them or directly counter Zip1’s anti-crossover activity. In the context of S. cerevisiae cells expressing K. l. ZIP1, K. l. Zip1 retains S. c. Zip1’s pro-crossover activity but lacks its anti-crossover activity, thus rendering MutSγ dispensable for the MutLγ-mediated resolution of Zip1/SC protein-associated recombination intermediates.


Separable Crossover-Promoting and Crossover-Constraining Aspects of Zip1 Activity during Budding Yeast Meiosis.

Voelkel-Meiman K, Johnston C, Thappeta Y, Subramanian VV, Hochwagen A, MacQueen AJ - PLoS Genet. (2015)

One model to explain the constrained relationship between MutSγ, SIC/Zip1-associated JMs, and MutLγ proteins and how K. l. Zip1 might bypass the constraint.Cartoons depict potential pathways for SC protein-MutSγ-MutLγ associated crossovers in budding yeast. At left is depicted S. cerevisiae expressing S. c. ZIP1, while at right is depicted S. cerevisiae expressing K. l. ZIP1. In these models, Zip1 maintains a pro-crossover function along with other SIC proteins and Msh4/Msh5, upstream of stabilized dHJs. Both S. c. Zip1 and K. l. Zip1 collaborate with other SIC proteins and Msh4/Msh5 to promote the establishment of stable JMs. In this model, S. c. Zip1 also has an anti-crossover activity that Msh4/Msh5 normally counters (left cartoon). This anti-crossover activity might be an intrinsic feature of the Zip1 protein or perhaps is an activity coming from SC formation. An antagonistic relationship between Msh4/Msh5 and S. c. Zip1 constrains Zip1-mediated, MutLγ-associated resolvase activity to act exclusively on MutSγ-associated recombination intermediates. In the context of S. cerevisiae cells expressing K. l. ZIP1 (right cartoon), K. l. Zip1 retains the pro-crossover activity but lacks the anti-crossover activity of S. c. Zip1, rendering MutSγ dispensable for MutLγ-dependent crossover recombination. Since K. l. Zip1 uncouples Mlh3-mediated crossover formation from both SC assembly and from a reliance on Msh4, we are drawn to the possibility that SC assembly normally constrains Zip1 crossovers–ensuring that they occur successfully only on Msh4-associated intermediates. We emphasize that the anti-crossover aspects of Zip1 activity could either be an action that destabilizes JM structures or one that prevents the accessibility of JM structures to MutLγ and other resolvase proteins.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4482702&req=5

pgen.1005335.g009: One model to explain the constrained relationship between MutSγ, SIC/Zip1-associated JMs, and MutLγ proteins and how K. l. Zip1 might bypass the constraint.Cartoons depict potential pathways for SC protein-MutSγ-MutLγ associated crossovers in budding yeast. At left is depicted S. cerevisiae expressing S. c. ZIP1, while at right is depicted S. cerevisiae expressing K. l. ZIP1. In these models, Zip1 maintains a pro-crossover function along with other SIC proteins and Msh4/Msh5, upstream of stabilized dHJs. Both S. c. Zip1 and K. l. Zip1 collaborate with other SIC proteins and Msh4/Msh5 to promote the establishment of stable JMs. In this model, S. c. Zip1 also has an anti-crossover activity that Msh4/Msh5 normally counters (left cartoon). This anti-crossover activity might be an intrinsic feature of the Zip1 protein or perhaps is an activity coming from SC formation. An antagonistic relationship between Msh4/Msh5 and S. c. Zip1 constrains Zip1-mediated, MutLγ-associated resolvase activity to act exclusively on MutSγ-associated recombination intermediates. In the context of S. cerevisiae cells expressing K. l. ZIP1 (right cartoon), K. l. Zip1 retains the pro-crossover activity but lacks the anti-crossover activity of S. c. Zip1, rendering MutSγ dispensable for MutLγ-dependent crossover recombination. Since K. l. Zip1 uncouples Mlh3-mediated crossover formation from both SC assembly and from a reliance on Msh4, we are drawn to the possibility that SC assembly normally constrains Zip1 crossovers–ensuring that they occur successfully only on Msh4-associated intermediates. We emphasize that the anti-crossover aspects of Zip1 activity could either be an action that destabilizes JM structures or one that prevents the accessibility of JM structures to MutLγ and other resolvase proteins.
Mentions: On the other hand, Fig 9 presents an alternative model to explain both the mechanism that normally constrains MutLγ activity to target MutSγ-associated recombination intermediates in S. cerevisiae and how K. l. Zip1 bypasses this constraint. In our alternative model, we propose that S. c. Zip1 is normally associated with both pro-crossover and anti-crossover activities, and that Msh4/Msh5 counters the anti-crossover activity of Zip1 at JMs. A possible anti-crossover aspect of Zip1 activity could be an action that destabilizes dHJ structures, or one that prevents the accessibility of dHJ structures to MutLγ-associated resolvase activity. The presence of MutSγ at JMs might protect them or directly counter Zip1’s anti-crossover activity. In the context of S. cerevisiae cells expressing K. l. ZIP1, K. l. Zip1 retains S. c. Zip1’s pro-crossover activity but lacks its anti-crossover activity, thus rendering MutSγ dispensable for the MutLγ-mediated resolution of Zip1/SC protein-associated recombination intermediates.

Bottom Line: While stable, full-length SC does not assemble in S. cerevisiae cells expressing K. lactis ZIP1, aggregates of K. lactis Zip1 displayed by S. cerevisiae meiotic nuclei are decorated with SC-associated proteins, and K. lactis Zip1 promotes the SUMOylation of the SC central element protein Ecm11, suggesting that K. lactis Zip1 functionally interfaces with components of the S. cerevisiae synapsis machinery.This separation-of-function version of Zip1 thus reveals that neither assembled SC nor MutSγ is required for Mlh3-dependent crossover formation per se in budding yeast.Our data suggest that features of S. cerevisiae Zip1 or of the assembled SC in S. cerevisiae normally constrain MutLγ to preferentially promote resolution of MutSγ-associated recombination intermediates.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology and Biochemistry, Wesleyan University, Middletown, Connecticut, United States of America.

ABSTRACT
Accurate chromosome segregation during meiosis relies on the presence of crossover events distributed among all chromosomes. MutSγ and MutLγ homologs (Msh4/5 and Mlh1/3) facilitate the formation of a prominent group of meiotic crossovers that mature within the context of an elaborate chromosomal structure called the synaptonemal complex (SC). SC proteins are required for intermediate steps in the formation of MutSγ-MutLγ crossovers, but whether the assembled SC structure per se is required for MutSγ-MutLγ-dependent crossover recombination events is unknown. Here we describe an interspecies complementation experiment that reveals that the mature SC is dispensable for the formation of Mlh3-dependent crossovers in budding yeast. Zip1 forms a major structural component of the budding yeast SC, and is also required for MutSγ and MutLγ-dependent crossover formation. Kluyveromyces lactis ZIP1 expressed in place of Saccharomyces cerevisiae ZIP1 in S. cerevisiae cells fails to support SC assembly (synapsis) but promotes wild-type crossover levels in those nuclei that progress to form spores. While stable, full-length SC does not assemble in S. cerevisiae cells expressing K. lactis ZIP1, aggregates of K. lactis Zip1 displayed by S. cerevisiae meiotic nuclei are decorated with SC-associated proteins, and K. lactis Zip1 promotes the SUMOylation of the SC central element protein Ecm11, suggesting that K. lactis Zip1 functionally interfaces with components of the S. cerevisiae synapsis machinery. Moreover, K. lactis Zip1-mediated crossovers rely on S. cerevisiae synapsis initiation proteins Zip3, Zip4, Spo16, as well as the Mlh3 protein, as do the crossovers mediated by S. cerevisiae Zip1. Surprisingly, however, K. lactis Zip1-mediated crossovers are largely Msh4/Msh5 (MutSγ)-independent. This separation-of-function version of Zip1 thus reveals that neither assembled SC nor MutSγ is required for Mlh3-dependent crossover formation per se in budding yeast. Our data suggest that features of S. cerevisiae Zip1 or of the assembled SC in S. cerevisiae normally constrain MutLγ to preferentially promote resolution of MutSγ-associated recombination intermediates.

No MeSH data available.