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Zhang Z, Zhan Z, Wang B, Chen Y, Chen X, Wan C, Fu Y, Huang L. Archaeal Chromatin Proteins Cren7 and Sul7d Compact DNA by Bending and Bridging. mBio 2020; 11:e00804-20. [PMID: 32518188 PMCID: PMC7373190 DOI: 10.1128/mbio.00804-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 05/06/2020] [Indexed: 11/20/2022] Open
Abstract
Archaeal chromatin proteins Cren7 and Sul7d from Sulfolobus are DNA benders. To better understand their architectural roles in chromosomal DNA organization, we analyzed DNA compaction by Cren7 and Sis7d, a Sul7d family member, from Sulfolobus islandicus at the single-molecule (SM) level by total single-molecule internal reflection fluorescence microscopy (SM-TIRFM) and atomic force microscopy (AFM). We show that both Cren7 and Sis7d were able to compact singly tethered λ DNA into a highly condensed structure in a three-step process and that Cren7 was over an order of magnitude more efficient than Sis7d in DNA compaction. The two proteins were similar in DNA bending kinetics but different in DNA condensation patterns. At saturating concentrations, Sis7d formed randomly distributed clusters whereas Cren7 generated a single and highly condensed core on plasmid DNA. This observation is consistent with the greater ability of Cren7 than of Sis7d to bridge DNA. Our results offer significant insights into the mechanism and kinetics of chromosomal DNA organization in Crenarchaea.IMPORTANCE A long-standing question is how chromosomal DNA is packaged in Crenarchaeota, a major group of archaea, which synthesize large amounts of unique small DNA-binding proteins but in general contain no archaeal histones. In the present work, we tested our hypothesis that the two well-studied crenarchaeal chromatin proteins Cren7 and Sul7d compact DNA by both DNA bending and bridging. We show that the two proteins are capable of compacting DNA, albeit with different efficiencies and in different manners, at the single molecule level. We demonstrate for the first time that the two proteins, which have long been regarded as DNA binders and benders, are able to mediate DNA bridging, and this previously unknown property of the proteins allows DNA to be packaged into highly condensed structures. Therefore, our results provide significant insights into the mechanism and kinetics of chromosomal DNA organization in Crenarchaeota.
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Affiliation(s)
- Zhenfeng Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Zhengyan Zhan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Bing Wang
- Hubei Key Lab of Genetic Regulation & Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Yuanyuan Chen
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xiuqiang Chen
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Cuihong Wan
- Hubei Key Lab of Genetic Regulation & Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Yu Fu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Li Huang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China
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Zhang Z, Zhao M, Chen Y, Wang L, Liu Q, Dong Y, Gong Y, Huang L. Architectural roles of Cren7 in folding crenarchaeal chromatin filament. Mol Microbiol 2019; 111:556-569. [PMID: 30499242 DOI: 10.1111/mmi.14173] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2018] [Indexed: 01/01/2023]
Abstract
Archaea have evolved various strategies in chromosomal organization. While histone homologues exist in most archaeal phyla, Cren7 is a chromatin protein conserved in the Crenarchaeota. Here, we show that Cren7 preferentially binds DNA with AT-rich sequences over that with GC-rich sequences with a binding size of 6~7 bp. Structural studies of Cren7 in complex with either an 18-bp or a 20-bp double-stranded DNA fragment reveal that Cren7 binds to the minor groove of DNA as monomers in a head-to-tail manner. The neighboring Cren7 monomers are located on the opposite sides of the DNA duplex, with each introducing a single-step sharp kink by intercalation of the hydrophobic side chain of Leu28, bending the DNA into an S-shape conformation. A structural model for the chromatin fiber folded by Cren7 was established and verified by the analysis of cross-linked Cren7-DNA complexes by atomic force microscopy. Our results suggest that Cren7 differs significantly from Sul7, another chromatin protein conserved among Sulfolobus species, in both DNA binding and deformation. These data shed significant light on the strategy of chromosomal DNA organization in crenarchaea.
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Affiliation(s)
- Zhenfeng Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road, Chaoyang District, Beijing, 100101, China
| | - Mohan Zhao
- Center for Multi-disciplinary Research, Institute of High Energy Physics, Chinese Academy of Sciences, 19B YuquanLu, Shijingshan District, Beijing, 100049, China
| | - Yuanyuan Chen
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
| | - Li Wang
- Center for Multi-disciplinary Research, Institute of High Energy Physics, Chinese Academy of Sciences, 19B YuquanLu, Shijingshan District, Beijing, 100049, China
| | - Qinghua Liu
- Center for Multi-disciplinary Research, Institute of High Energy Physics, Chinese Academy of Sciences, 19B YuquanLu, Shijingshan District, Beijing, 100049, China
| | - Yuhui Dong
- Center for Multi-disciplinary Research, Institute of High Energy Physics, Chinese Academy of Sciences, 19B YuquanLu, Shijingshan District, Beijing, 100049, China
| | - Yong Gong
- Center for Multi-disciplinary Research, Institute of High Energy Physics, Chinese Academy of Sciences, 19B YuquanLu, Shijingshan District, Beijing, 100049, China
| | - Li Huang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road, Chaoyang District, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Shijingshan District, Beijing, 100049, China
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