Biology subjects

Forsburg, S. L.

Publications and source records attributed to Forsburg, S. L..

4 recordsLinked to original sources

bioRxiv2020

A visual atlas of meiotic protein dynamics in living fission yeast

Meiosis is a carefully choreographed dynamic process that re-purposes proteins from somatic/vegetative cell division, as well as meiosis-specific factors, to carry out the differentiation and recombination pathway common to sexually reproducing eukaryotes. Studies of individual proteins from a variety of different experimental protocols can make it difficult to compare details between them. Using a consistent protocol in otherwise wild type fission yeast cells, this report provides an atlas of dynamic protein behavior of representative proteins at different stages during normal zygotic meiosis in fission yeast. This establishes common landmarks to facilitate comparison of different proteins and shows that initiation of S phase likely occurs prior to nuclear fusion/karyogamy. SummaryMeiosis is an important process for sexually reproducing organisms. Unique dynamics of recombination and chromosome segregation are required for this differentiation process. Fission yeast is an excellent model to study meiotic progression and chromosome dynamics. Historically, different methodologies have been used to examine protein dynamics in fixed or live cells, which makes comparisons more difficult. In this report, we use fluorescently tagged proteins and live-cell microscopy under uniform conditions to compare meiotic signposts that define dynamic behavior of proteins during meiotic DNA synthesis, nuclear fusion, chromosome alignment, genetic recombination, metaphase, and meiosis. This establishes a reference atlas of protein behavior during meiotic differentiation.

cell biology↗

bioRxiv2020

Monitoring S. pombe genome stress by visualizing end-binding protein Ku

Studies of genome stability have exploited visualization of fluorescently tagged proteins in live cells to characterize DNA damage, checkpoint, and repair responses. In this report, we describe a new tool for fission yeast, a tagged version of the end-binding protein Pku70 which is part of the KU protein complex. We compare Pku70 localization to other markers upon treatment to various genotoxins, and identify a unique pattern of distribution. Pku70 provides a new tool to define and characterize DNA lesions and the repair response.

molecular biology↗

bioRxiv2020

Schizosaccharomyces pombe KAT5 contributes to resection and repair of a DNA double strand break

Chromatin remodeling is essential for effective repair of a DNA double strand break. KAT5 (S. pombe Mst1, human TIP60) is a MYST family histone acetyltransferase conserved from yeast to humans that coordinates various DNA damage response activities at a DNA double strand break (DSB), including histone remodeling and activation of the DNA damage checkpoint. In S. pombe, mutations in mst1+ causes sensitivity to DNA damaging drugs. Here we show that Mst1 is recruited to DSBs. Mutation of mst1+ disrupts recruitment of repair proteins and delays resection. These defects are partially rescued by deletion of pku70, which has been previously shown to antagonize repair by homologous recombination. These phenotypes of mst1 are similar to pht1-4KR, a non-acetylatable form of histone variant H2A.Z, which has been proposed to affect resection. Our data suggest that Mst1 functions to direct repair of DSBs towards homologous recombination pathways by modulating resection at the double strand break.

genetics↗

bioRxiv2019

Checkpoint regulation of nuclear Tos4 defines S phase arrest in fission yeast

From yeast to humans, the cell cycle is tightly controlled by regulatory networks that regulate cell proliferation and can be monitored by dynamic visual markers in living cells. We have observed S phase progression by monitoring nuclear accumulation of the FHA-containing DNA binding protein Tos4, which is expressed in the G1/S phase transition. We use Tos4 localization to distinguish three classes of DNA replication mutants: those that arrest with an apparent 1C DNA content and accumulate Tos4 at the restrictive temperature; those that arrest with an apparent 2C DNA content, that do not accumulate Tos4; and those that proceed into mitosis despite a 1C DNA content, again without Tos4 accumulation. Our data indicate that Tos4 localization in these conditions is responsive to checkpoint kinases, with activation of the Cds1 checkpoint kinase promoting Tos4 retention in the nucleus, and activation of the Chk1 damage checkpoint promoting its turnover. Tos4 localization therefore allows us to monitor checkpoint-dependent activation that responds to replication failure in early versus late S phase.

cell biology↗