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Chang L, Wang D, Peng C, Wang Q, Xu B, Tong Z. A method for high-concentration agarose gel preparation and its application in high-resolution separation of low-molecular-weight nucleic acids and proteins. Int J Biol Macromol 2023; 231:123358. [PMID: 36693602 DOI: 10.1016/j.ijbiomac.2023.123358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 01/10/2023] [Accepted: 01/17/2023] [Indexed: 01/22/2023]
Abstract
Separation of nucleic acids and proteins using gels has always been a crucial part of molecular biology research. For low-molecular-weight nucleic acids and proteins, low- and medium-concentration agarose gels cannot achieve the high resolution as polyacrylamide gels. We found that 6 %-14 % high-concentration agarose gels (HAGs) could be easily dissolved in an autoclave and the vertical gel cast can be effortlessly filled using an easy-made plastic box. Coupled with the improved buffer condition, HAG electrophoresis resulted in a good resolution of DNA and protein bands. With conventional TBE buffer plus 0.2 % NaCl, DNA fragments that differ by 2-5-bp within the 50-200-bp size range can be resolved on 6 %-8 % HAGs. By using TBE without NaCl, DNA fragments that differ by 2-bp or 2-nt within the 10-100-bp size range can be well resolved on >8 % HAGs. Using a buffer system comprising 1 M Tris-Cl for gel preparation, 0.2 M Tris-Cl/0.2 % SDS as upper tank buffer, and 0.2 M Tris-Cl as the lower tank buffer, HAGs achieved good molecular weight separation of total bacterial and plant proteins in the 10-200 kDa range. In conclusion, we developed a method for HAG preparation and electrophoresis of low-molecular-weight nucleic acids and proteins.
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Affiliation(s)
- Lili Chang
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences & Key Laboratory for Biology and Genetic Resources of Tropical Crops of Hainan Province, Hainan Institute for Tropical Agricultural Resources, Haikou 571101, China
| | - Dan Wang
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences & Key Laboratory for Biology and Genetic Resources of Tropical Crops of Hainan Province, Hainan Institute for Tropical Agricultural Resources, Haikou 571101, China
| | - Cunzhi Peng
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences & Key Laboratory for Biology and Genetic Resources of Tropical Crops of Hainan Province, Hainan Institute for Tropical Agricultural Resources, Haikou 571101, China
| | - Qi Wang
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences & Key Laboratory for Biology and Genetic Resources of Tropical Crops of Hainan Province, Hainan Institute for Tropical Agricultural Resources, Haikou 571101, China
| | - Bingqiang Xu
- Haikou Experimental Station, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, China.
| | - Zheng Tong
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences & Key Laboratory for Biology and Genetic Resources of Tropical Crops of Hainan Province, Hainan Institute for Tropical Agricultural Resources, Haikou 571101, China.
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Kim JH, Modena MS, Sehgal E, Courney A, Neudorf C, Arribere J. SMG-6 mRNA cleavage stalls ribosomes near premature stop codons in vivo. Nucleic Acids Res 2022; 50:8852-8866. [PMID: 35950494 PMCID: PMC9410879 DOI: 10.1093/nar/gkac681] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/29/2022] [Accepted: 07/26/2022] [Indexed: 12/24/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) protects cells from the toxic and potentially dominant effects of truncated proteins. Targeting of mRNAs with early stop codons is mediated by the ribosome and spatiotemporally aligned with translation termination. Previously we identified a novel NMD intermediate: ribosomes stalled on cleaved stop codons, raising the possibility that NMD begins even prior to ribosome removal from the stop codon. Here we show that this intermediate is the result of mRNA cleavage by the endonuclease SMG-6. Our work supports a model in which ribosomes stall secondary to SMG-6 mRNA cleavage in Caenorhabditis elegans and humans, i.e. that the novel NMD intermediate occurs after a prior ribosome elicits NMD. Our genetic analysis of C. elegans' SMG-6 supports a central role for SMG-6 in metazoan NMD, and provides a context for evaluating its function in other metazoans.
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Affiliation(s)
- John H Kim
- Department of MCD Biology, UC Santa Cruz, California, USA
| | | | - Enisha Sehgal
- Department of MCD Biology, UC Santa Cruz, California, USA
| | - Annie Courney
- Department of MCD Biology, UC Santa Cruz, California, USA
| | - Celine W Neudorf
- Department of Biomolecular Engineering, UC Santa Cruz, California, USA
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Behler J, Hess WR. Approaches to study CRISPR RNA biogenesis and the key players involved. Methods 2020; 172:12-26. [PMID: 31325492 DOI: 10.1016/j.ymeth.2019.07.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 05/29/2019] [Accepted: 07/15/2019] [Indexed: 12/26/2022] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins provide an inheritable and adaptive immune system against phages and foreign genetic elements in many bacteria and archaea. The three stages of CRISPR-Cas immunity comprise adaptation, CRISPR RNA (crRNA) biogenesis and interference. The maturation of the pre-crRNA into mature crRNAs, short guide RNAs that target invading nucleic acids, is crucial for the functionality of CRISPR-Cas defense systems. Mature crRNAs assemble with Cas proteins into the ribonucleoprotein (RNP) effector complex and guide the Cas nucleases to the cognate foreign DNA or RNA target. Experimental approaches to characterize these crRNAs, the specific steps toward their maturation and the involved factors, include RNA-seq analyses, enzyme assays, methods such as cryo-electron microscopy, the crystallization of proteins, or UV-induced protein-RNA crosslinking coupled to mass spectrometry analysis. Complex and multiple interactions exist between CRISPR-cas-encoded specific riboendonucleases such as Cas6, Cas5d and Csf5, endonucleases with dual functions in maturation and interference such as the enzymes of the Cas12 and Cas13 families, and nucleases belonging to the cell's degradosome such as RNase E, PNPase and RNase J, both in the maturation as well as in interference. The results of these studies have yielded a picture of unprecedented diversity of sequences, enzymes and biochemical mechanisms.
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Affiliation(s)
- Juliane Behler
- University of Freiburg, Faculty of Biology, Genetics and Experimental Bioinformatics, Schänzlestr. 1, D-79104 Freiburg, Germany
| | - Wolfgang R Hess
- University of Freiburg, Faculty of Biology, Genetics and Experimental Bioinformatics, Schänzlestr. 1, D-79104 Freiburg, Germany; University of Freiburg, Freiburg Institute for Advanced Studies, Albertstr. 19, D-79104 Freiburg, Germany.
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Mohr G, Silas S, Stamos JL, Makarova KS, Markham LM, Yao J, Lucas-Elío P, Sanchez-Amat A, Fire AZ, Koonin EV, Lambowitz AM. A Reverse Transcriptase-Cas1 Fusion Protein Contains a Cas6 Domain Required for Both CRISPR RNA Biogenesis and RNA Spacer Acquisition. Mol Cell 2018; 72:700-714.e8. [PMID: 30344094 PMCID: PMC6242336 DOI: 10.1016/j.molcel.2018.09.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/10/2018] [Accepted: 09/12/2018] [Indexed: 01/30/2023]
Abstract
Prokaryotic CRISPR-Cas systems provide adaptive immunity by integrating portions of foreign nucleic acids (spacers) into genomic CRISPR arrays. Cas6 proteins then process CRISPR array transcripts into spacer-derived RNAs (CRISPR RNAs; crRNAs) that target Cas nucleases to matching invaders. We find that a Marinomonas mediterranea fusion protein combines three enzymatic domains (Cas6, reverse transcriptase [RT], and Cas1), which function in both crRNA biogenesis and spacer acquisition from RNA and DNA. We report a crystal structure of this divergent Cas6, identify amino acids required for Cas6 activity, show that the Cas6 domain is required for RT activity and RNA spacer acquisition, and demonstrate that CRISPR-repeat binding to Cas6 regulates RT activity. Co-evolution of putative interacting surfaces suggests a specific structural interaction between the Cas6 and RT domains, and phylogenetic analysis reveals repeated, stable association of free-standing Cas6s with CRISPR RTs in multiple microbial lineages, indicating that a functional interaction between these proteins preceded evolution of the fusion.
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Affiliation(s)
- Georg Mohr
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Sukrit Silas
- Department of Pathology, Stanford University, Stanford, CA 94305, USA; Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Jennifer L Stamos
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD 20894, USA
| | - Laura M Markham
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Jun Yao
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Patricia Lucas-Elío
- Department of Genetics and Microbiology, Universidad de Murcia, Murcia 30100, Spain
| | - Antonio Sanchez-Amat
- Department of Genetics and Microbiology, Universidad de Murcia, Murcia 30100, Spain
| | - Andrew Z Fire
- Department of Pathology, Stanford University, Stanford, CA 94305, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD 20894, USA
| | - Alan M Lambowitz
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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Silas S, Lucas-Elio P, Jackson SA, Aroca-Crevillén A, Hansen LL, Fineran PC, Fire AZ, Sánchez-Amat A. Type III CRISPR-Cas systems can provide redundancy to counteract viral escape from type I systems. eLife 2017; 6:27601. [PMID: 28826484 PMCID: PMC5576922 DOI: 10.7554/elife.27601] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 08/07/2017] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas-mediated defense utilizes information stored as spacers in CRISPR arrays to defend against genetic invaders. We define the mode of target interference and role in antiviral defense for two CRISPR-Cas systems in Marinomonas mediterranea. One system (type I-F) targets DNA. A second system (type III-B) is broadly capable of acquiring spacers in either orientation from RNA and DNA, and exhibits transcription-dependent DNA interference. Examining resistance to phages isolated from Mediterranean seagrass meadows, we found that the type III-B machinery co-opts type I-F CRISPR-RNAs. Sequencing and infectivity assessments of related bacterial and phage strains suggests an ‘arms race’ in which phage escape from the type I-F system can be overcome through use of type I-F spacers by a horizontally-acquired type III-B system. We propose that the phage-host arms race can drive selection for horizontal uptake and maintenance of promiscuous type III interference modules that supplement existing host type I CRISPR-Cas systems.
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Affiliation(s)
- Sukrit Silas
- Department of Pathology, Stanford University, Stanford, United States.,Department of Chemical and Systems Biology, Stanford University, Stanford, United States
| | - Patricia Lucas-Elio
- Department of Genetics and Microbiology, Universidad de Murcia, Murcia, Spain
| | - Simon A Jackson
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | | | - Loren L Hansen
- Department of Pathology, Stanford University, Stanford, United States
| | - Peter C Fineran
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.,Bio-Protection Research Centre, University of Otago, Dunedin, New Zealand
| | - Andrew Z Fire
- Department of Pathology, Stanford University, Stanford, United States
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