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Ma OX, Chong WG, Lee JKE, Cai S, Siebert CA, Howe A, Zhang P, Shi J, Surana U, Gan L. Cryo-ET detects bundled triple helices but not ladders in meiotic budding yeast. PLoS One 2022; 17:e0266035. [PMID: 35421110 PMCID: PMC9009673 DOI: 10.1371/journal.pone.0266035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 03/13/2022] [Indexed: 11/19/2022] Open
Abstract
In meiosis, cells undergo two sequential rounds of cell division, termed meiosis I and meiosis II. Textbook models of the meiosis I substage called pachytene show that nuclei have conspicuous 100-nm-wide, ladder-like synaptonemal complexes and ordered chromatin loops. It remains unknown if these cells have any other large, meiosis-related intranuclear structures. Here we present cryo-ET analysis of frozen-hydrated budding yeast cells before, during, and after pachytene. We found no cryo-ET densities that resemble dense ladder-like structures or ordered chromatin loops. Instead, we found large numbers of 12-nm-wide triple-helices that pack into ordered bundles. These structures, herein called meiotic triple helices (MTHs), are present in meiotic cells, but not in interphase cells. MTHs are enriched in the nucleus but not enriched in the cytoplasm. Bundles of MTHs form at the same timeframe as synaptonemal complexes (SCs) in wild-type cells and in mutant cells that are unable to form SCs. These results suggest that in yeast, SCs coexist with previously unreported large, ordered assemblies.
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Affiliation(s)
- Olivia X. Ma
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Wen Guan Chong
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Joy K. E. Lee
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Shujun Cai
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - C. Alistair Siebert
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom
| | - Andrew Howe
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom
| | - Peijun Zhang
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Jian Shi
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Uttam Surana
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Proteos, Singapore
- Bioprocessing Technology Institute, A*STAR, Singapore, Singapore
- Biotransformation Innovation Platform, A*STAR, Singapore, Singapore
- Department of Pharmacology, National University of Singapore, Singapore, Singapore
| | - Lu Gan
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
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