Journal of Microbiology

Kiwon Rhee

2 Articles

A Method for Physical Analysis of Recombination Intermediates in Saccharomyces cerevisiae: Kiwon Rhee , Hyungseok Choi , Keun P. Kim , Jeong H. Joo; J. Microbiol. 2023;61(11):939-951. Published online December 11, 2023; DOI: https://doi.org/10.1007/s12275-023-00094-w

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Meiosis is a process through which diploid cells divide into haploid cells, thus promoting genetic diversity. This diversity arises from the formation of genetic crossovers (COs) that repair DNA double-strand breaks (DSBs), through homologous recombination (HR). Deficiencies in HR can lead to chromosomal abnormality resulting from chromosomal nondisjunction, and genetic disorders. Therefore, investigating the mechanisms underlying effective HR is crucial for reducing genome instability. Budding yeast serves as an ideal model for studying HR mechanisms due to its amenability to gene modifications and the ease of inducing synchronized meiosis to yield four spores. During meiosis, at the DNA level, programmed DSBs are repaired as COs or non-crossovers (NCOs) through structural alterations in the nascent D-loop, involving single-end invasions (SEIs) and double-Holliday junctions (dHJs). This repair occurs using homologous templates rather than sister templates. This protocol, using Southern blotting, allows for the analysis and monitoring of changes in DNA structures in the recombination process. One-dimensional (1D) gel electrophoresis is employed to detect DSBs, COs, and NCOs, while twodimensional (2D) gel electrophoresis is utilized to identify joint molecules (JMs). Therefore, physical analysis is considered the most effective method for investigating the HR mechanism. Our protocol provides more comprehensive information than previous reports by introducing conditions for obtaining a greater number of cells from synchronized yeast and a method that can analyze not only meiotic/mitotic recombination but also mitotic replication.

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Prophase roles of replication protein A in crossover formation and meiotic progression
Rose M. Lee, Keun Pil Kim, Jeong H. Joo
Journal of Microbiology.2026; 64(6): e2604001. CrossRef
Recombination-coupled DNA synthesis facilitates post-invasion steps in meiotic crossover and noncrossover formations
Hyungseok Choi, Jun Seo Lee, Jeong H Joo, Soogene Lee, Keun P Kim
Nucleic Acids Research.2025;[Epub] CrossRef

Yeast polyubiquitin unit regulates synaptonemal complex formation and recombination during meiosis: Min-Kyung Jo , Kiwon Rhee , Keun Pil Kim , Soogil Hong; J. Microbiol. 2022;60(7):705-714. Published online July 4, 2022; DOI: https://doi.org/10.1007/s12275-022-2204-y

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Abstract PDF

Ubiquitin is highly conserved in most eukaryotes and involved in diverse physiological processes, including cell division, protein quality control, and protein degradation mediated by the ubiquitin-proteasome system after heat shock, glucose-starvation, and oxidative stress. However, the role of the ubiquitin gene UBI4, which contains five consecutive head-to-tail ubiquitin repeats, in meiosis has not been investigated. In this study, we show that the Saccharomyces cerevisiae polyubiquitin precursor gene, UBI4, is required to promote synaptonemal complex (SC) formation and suppress excess doublestrand break formation. Moreover, the proportion of Zip1 polycomplexes, which indicate abnormal SC formation, in cells with a mutation in UBI4 (i.e., ubi4Δ cells) is higher than that of wild-type cells, implying that the UBI4 plays an important role in the early meiotic prophase I. Interestingly, although ubi4Δ cells rarely form full-length SCs in the pachytene stage of prophase I, the Zip3 foci are still seen, as in wild-type cells. Moreover, ubi4Δ cells proficiently form crossover and noncrossover products with a slight delay compared to wild-type cells, suggesting that UBI4 is dispensable in SCcoupled recombination. Our findings demonstrate that UBI4 exhibits dual functions that are associated with both positive and negative roles in SC formation and recombination during meiosis.

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Citations to this article as recorded by

Prophase roles of replication protein A in crossover formation and meiotic progression
Rose M. Lee, Keun Pil Kim, Jeong H. Joo
Journal of Microbiology.2026; 64(6): e2604001. CrossRef
The deubiquitinase Usp7 in Drosophila melanogaster is required for synaptonemal complex maintenance
Cathleen M. Lake, Jennifer Gardner, Salam Briggs, Zulin Yu, Grace McKown, R. Scott Hawley
Proceedings of the National Academy of Sciences.2024;[Epub] CrossRef

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