The N-Terminal Region of the Polo Kinase Cdc5 Is Required for Downregulation of the Meiotic Recombination Checkpoint.

Sara González-Arranz,Isabel Acosta,Pedro A San-Segundo,Beatriz Santos,Jesús A Carballo

doi:10.3390/cells10102561

Abstract

During meiosis, the budding yeast polo-like kinase Cdc5 is a crucial driver of the prophase I to meiosis I (G2/M) transition. The meiotic recombination checkpoint restrains cell cycle progression in response to defective recombination to ensure proper distribution of intact chromosomes to the gametes. This checkpoint detects unrepaired DSBs and initiates a signaling cascade that ultimately inhibits Ndt80, a transcription factor required for CDC5 gene expression. Previous work revealed that overexpression of CDC5 partially alleviates the checkpoint-imposed meiotic delay in the synaptonemal complex-defective zip1Δ mutant. Here, we show that overproduction of a Cdc5 version (Cdc5-ΔN70), lacking the N-terminal region required for targeted degradation of the protein by the APC/C complex, fails to relieve the zip1Δ-induced meiotic delay, despite being more stable and reaching increased protein levels. However, precise mutation of the consensus motifs for APC/C recognition (D-boxes and KEN) has no effect on Cdc5 stability or function during meiosis. Compared to the zip1Δ single mutant, the zip1Δ cdc5-ΔN70 double mutant exhibits an exacerbated meiotic block and reduced levels of Ndt80 consistent with persistent checkpoint activity. Finally, using a CDC5-inducible system, we demonstrate that the N-terminal region of Cdc5 is essential for its checkpoint erasing function. Thus, our results unveil an additional layer of regulation of polo-like kinase function in meiotic cell cycle control.

Highlights

IntroductionConserved Polo-like kinases (PLKs) are essential regulators of both mitotic and meiotic cell cycles
We have previously reported that overexpression of CDC5 from a high-copy plasmid partially suppresses the robust delay in meiotic progression of the zip1∆ mutant imposed by the action of the meiotic recombination checkpoint ([39]; Figure 1B)
In order to gain additional insight into this meiotic function of Cdc5, we searched for other domains of Cdc5 that could influence its impact on the meiotic recombination checkpoint response

Summary

Introduction

Conserved Polo-like kinases (PLKs) are essential regulators of both mitotic and meiotic cell cycles. In addition to the kinase domain, PLKs are characterized by the presence of the polo-box domain (Figure 1A) that mediates the localization and recognition of their substrates, often primed by previous phosphorylation, providing an exquisite spatiotemporal mechanism for their regulation [1]. Unlike other organisms, such as worms and mammals, in the budding yeast Saccharomyces cerevisiae there is a single member of this PLK family, the Cdc protein. Cdc participates in the DNA damage response [2]

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Conclusion