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Petersen KV, Tesauro C, Hede MS, Pages C, Marcussen LB, Keller JG, Bugge M, Holm K, Bjergbæk L, Stougaard M, Wejse C, Knudsen BR. Rolling Circle Enhanced Detection of Specific Restriction Endonuclease Activities in Crude Cell Extracts. Sensors (Basel) 2022; 22:7763. [PMID: 36298113 PMCID: PMC9608553 DOI: 10.3390/s22207763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/26/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Restriction endonucleases are expressed in all bacteria investigated so far and play an essential role for the bacterial defense against viral infections. Besides their important biological role, restriction endonucleases are of great use for different biotechnological purposes and are indispensable for many cloning and sequencing procedures. Methods for specific detection of restriction endonuclease activities can therefore find broad use for many purposes. In the current study, we demonstrate proof-of-concept for a new principle for the detection of restriction endonuclease activities. The method is based on rolling circle amplification of circular DNA products that can only be formed upon restriction digestion of specially designed DNA substrates. By combining the activity of the target restriction endonuclease with the highly specific Cre recombinase to generate DNA circles, we demonstrate specific detection of selected restriction endonuclease activities even in crude cell extracts. This is, to our knowledge, the first example of a sensor system that allows activity measurements of restriction endonucleases in crude samples. The presented sensor system may prove valuable for future characterization of bacteria species or strains based on their expression of restriction endonucleases as well as for quantification of restriction endonuclease activities directly in extracts from recombinant cells.
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Affiliation(s)
- Kamilla Vandsø Petersen
- Department of Clinical Medicine, Aarhus University, 8000 Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
- VPCIR Biosciences Aps, 8000 Aarhus, Denmark
| | | | | | - Camilla Pages
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Lærke Bay Marcussen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Josephine Geertsen Keller
- Department of Clinical Medicine, Aarhus University, 8000 Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Magnus Bugge
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Kasper Holm
- Department of Pathology, Aarhus University Hospital, 8000 Aarhus, Denmark
| | - Lotte Bjergbæk
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Magnus Stougaard
- Department of Clinical Medicine, Aarhus University, 8000 Aarhus, Denmark
- Department of Pathology, Aarhus University Hospital, 8000 Aarhus, Denmark
| | - Christian Wejse
- Department of Clinical Medicine, Aarhus University, 8000 Aarhus, Denmark
- Department of Public Health, Aarhus University, 8000 Aarhus, Denmark
| | - Birgitta R. Knudsen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
- VPCIR Biosciences Aps, 8000 Aarhus, Denmark
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2
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Zaib S, Saleem MA, Khan I. CRISPR-Cas9 Genome Engineering: Trends in Medicine and Health. Mini Rev Med Chem 2022; 22:410-421. [PMID: 34517795 DOI: 10.2174/1389557521666210913112030] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 12/13/2020] [Accepted: 01/14/2021] [Indexed: 11/22/2022]
Abstract
The ability to engineer biological systems and organisms holds enormous potential for applications across basic science, medicine, and biotechnology. Over the past few decades, the development of CRISPR (clustered regularly interspaced short palindromic repeat) has revolutionized the whole genetic engineering process utilizing the principles of Watson-Crick base pairing. CRISPRCas9 technology offers the simplest, fastest, most versatile, reliable, and precise method of genetic manipulation, thus enabling geneticists and medical researchers to edit parts of the genome by removing, adding, or altering sections of the DNA sequence. The current review focuses on the applications of CRISPR-Cas9 in the field of medical research. Compared with other gene-editing technologies, CRISPR/Cas9 demonstrates numerous advantages for the treatment of various medical conditions, including cancer, hepatitis B, cardiovascular diseases, or even high cholesterol. Given its promising performance, CRISPR/Cas9 gene-editing technology will surely help in the therapy of several disorders while addressing the issues pertaining to the minimization of the off-target effects of gene editing and incomplete matches between sgRNA and genomic DNA by Cas9.
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Affiliation(s)
- Sumera Zaib
- Department of Biochemistry, Faculty of Life Sciences, University of Central Punjab, Lahore-54590, Pakistan
| | - Mushtaq A Saleem
- Ghazi National Institute of Engineering & Sciences -GNIES, Dera Ghazi Khan-32200, Pakistan
| | - Imtiaz Khan
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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Szewczuk M, Boguszewska K, Kaźmierczak-Barańska J, Karwowski BT. The Influence of 5' R and 5' S cdA and cdG on the Activity of BsmAI and SspI Restriction Enzymes. Molecules 2021; 26:molecules26123750. [PMID: 34205449 PMCID: PMC8234751 DOI: 10.3390/molecules26123750] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/11/2021] [Accepted: 06/15/2021] [Indexed: 01/03/2023] Open
Abstract
Restriction endonucleases (REs) are intra-bacterial scissors that are considered tools in the fight against foreign genetic material. SspI and BsmAI, examined in this study, cleave dsDNA at their site of recognition or within a short distance of it. Both enzymes are representatives of type II REs, which have played an extremely important role in research on the genetics of organisms and molecular biology. Therefore, the study of agents affecting their activity has become highly important. Ionizing radiation may damage basic cellular mechanisms by inducing lesions in the genome, with 5',8-cyclo-2'-deoxypurines (cdPus) as a model example. Since cdPus may become components of clustered DNA lesions (CDLs), which are unfavorable for DNA repair pathways, their impact on other cellular mechanisms is worthy of attention. This study investigated the influence of cdPus on the elements of the bacterial restriction-modification system. In this study, it was shown that cdPus present in DNA affect the activity of REs. SspI was blocked by any cdPu lesion present at the enzyme's recognition site. When lesions were placed near the recognition sequence, the SspI was inhibited up to 46%. Moreover, (5'S)-5',8-cyclo-2'-deoxyadenosine (ScdA) present in the oligonucleotide sequence lowered BsmAI activity more than (5'R)-5',8-cyclo-2'-deoxyadenosine (RcdA). Interestingly, in the case of 5',8-cyclo-2'-deoxyguanosine (cdG), both 5'S and 5'R diastereomers inhibited BsmAI activity (up to 55% more than cdA). The inhibition was weaker when cdG was present at the recognition site rather than the cleavage site.
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Abstract
The emergence of a mutant strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with an amino acid change from aspartate to a glycine residue at position 614 (D614G) has been reported and this mutant appears to be now dominant in the pandemic. Efficient detection of the SARS-CoV-2 D614G mutant by biosensing technologies is therefore crucial for the control of the pandemic.
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Affiliation(s)
- Yang Zhang
- College of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong, 518055, China.
| | - Hui Xi
- College of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong, 518055, China
| | - Mario Juhas
- Medical and Molecular Microbiology Unit, Department of Medicine, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
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5
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Sugimoto H, Hirano M, Tanaka H, Tanaka T, Kitagawa-Yogo R, Muramoto N, Mitsukawa N. Plastid-targeted forms of restriction endonucleases enhance the plastid genome rearrangement rate and trigger the reorganization of its genomic architecture. Plant J 2020; 102:1042-1057. [PMID: 31925982 DOI: 10.1111/tpj.14687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/25/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
Plant cells have acquired chloroplasts (plastids) with a unique genome (ptDNA), which developed during the evolution of endosymbiosis. The gene content and genome structure of ptDNAs in land plants are considerably stable, although those of algal ptDNAs are highly varied. Plant cells seem, therefore, to be intolerant of any structural or organizational changes in the ptDNA. Genome rearrangement functions as a driver of genomic evolutionary divergence. Here, we aimed to create various types of rearrangements in the ptDNA of Arabidopsis genomes using plastid-targeted forms of restriction endonucleases (pREs). Arabidopsis plants expressing each of the three specific pREs, i.e., pTaqI, pHinP1I, and pMseI, were generated; they showed the leaf variegation phenotypes associated with impaired chloroplast development. We confirmed that these pREs caused double-stranded breaks (DSB) at their recognition sites in ptDNAs. Genome-wide analysis of ptDNAs revealed that the transgenic lines exhibited a large number of rearrangements such as inversions and deletions/duplications, which were dominantly repaired by microhomology-mediated recombination and microhomology-mediated end-joining, and less by non-homologous end-joining. Notably, pHinP1I, which recognized a small number of sites in ptDNA, induced drastic structural changes, including regional copy number variations throughout ptDNAs. In contrast, the transient expression of either pTaqI or pMseI, whose recognition site numbers were relatively larger, resulted in small-scale changes at the whole genome level. These results indicated that DSB frequencies and their distribution are major determinants in shaping ptDNAs.
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Affiliation(s)
- Hiroki Sugimoto
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Minoru Hirano
- Bio System Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Hidenori Tanaka
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Tomoko Tanaka
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Ritsuko Kitagawa-Yogo
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Nobuhiko Muramoto
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Norihiro Mitsukawa
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
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Abstract
We report here experiments carried out with nonpathogenic Escherichia coli bacterial strains and their phages. This research yielded interesting insights into their activities, occasionally producing genetic variants of different types. In order to not interfere with the genetic stability of the parental strains involved, we found that the bacteria are genetically equipped to only rarely produce a genetic variant, which may occur by a number of different approaches. On the one hand, the genes of relevance for the production of specific genetic variants are relatively rarely expressed. On the other hand, other gene products act as moderators of the frequencies that produce genetic variants. We call the genes producing genetic variants and those moderating the frequencies of genetic variation “evolution genes”. Their products are generally not required for daily bacterial life. We can, therefore, conclude that the bacterial genome has a duality. Some of the bacterial enzymes involved in biological evolution have become useful tools (e.g., restriction endonucleases) for molecular genetic research involving the genetic set-up of any living organism.
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Affiliation(s)
- Werner Arber
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
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Jakubovska J, Tauraitė D, Meškys R. Transient N 4 -Acyl-DNA Protection against Cleavage by Restriction Endonucleases. Chembiochem 2019; 20:2504-2512. [PMID: 31090133 DOI: 10.1002/cbic.201900280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Indexed: 01/06/2023]
Abstract
A set of five N4 -acyl-modified 2'-deoxycytidine 5'-triphosphates were incorporated into modified DNA by using phi29 DNA polymerase, and cleavage by selected restriction endonucleases was studied. Modified DNA containing N4 -acyl functional groups in either one or both strands of a DNA molecule was resistant to the majority of restriction enzymes tested, whereas modifications outside of the recognition sequences were well tolerated. The N4 -acylated cytidine derivatives were subjected to competitive nucleotide incorporation by using phi29 DNA polymerase, showing that a high-fidelity phi29 DNA polymerase efficiently used the modified analogues in the presence of its natural counterpart. These N4 modifications were also demonstrated to be easily removed in an aqueous ethanolamine solution, in which all steps, including primer extension, demodification, and cleavage by restriction endonuclease, could be performed in a one-pot procedure that eliminated additional purification stages. It is suggested that N4 -modified nucleotides are promising building blocks for a programmable; transient; and, most importantly, straightforward DNA protection against specific endonucleases.
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Affiliation(s)
- Jevgenija Jakubovska
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio av. 7, 10257, Vilnius, Lithuania
| | - Daiva Tauraitė
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio av. 7, 10257, Vilnius, Lithuania
| | - Rolandas Meškys
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio av. 7, 10257, Vilnius, Lithuania
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Abstract
Restriction-modification (R-M) was discovered because it provides bacteria with immunity to phage infection. But, is phage-mediated selection the sole mechanism responsible for the evolution and maintenance of these ubiquitous and multiply evolved systems? In an effort to answer this question, we have performed experiments with laboratory populations of E. coli and phage and computer simulations. We consider two ecological situations whereby phage-mediated selection could favor R-M immunity; i) when bacteria with a novel R-M system invade communities of phage-sensitive bacteria in which there are one or more species of phage, and ii) when bacteria colonize bacterial-free habitats in which phage are present. The results of our experiments indicate that in established communities of bacteria and phage, the advantage R-M provides an invading population of bacteria is ephemeral. Within short order, mutants resistant (refractory) to the phage evolve in the dominant population and subsequently in the invading population. The outcome of competition then depends on the relative fitness of the resistant states of these bacterial clones, rather than R-M. As a consequence of sequential selection for independent mutants, this rapid evolution of resistance occurs even when two and three species of phage are present. While in our experiments resistance also evolved when bacteria colonized new habitats in which phage were present, a novel R-M system greatly augmented the likelihood of their becoming established. We interpret the results of this study as support for the hypothesis that the latter, colonization selection, may play an important role in the evolution and maintenance of restriction-modification. However, we also see these results and other observations we discuss as questioning whether protection against phage is the unique biological role of restriction-modification.
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Affiliation(s)
- Ryszard Korona
- Department of Zoology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Bruce R Levin
- Department of Zoology, University of Massachusetts, Amherst, MA, 01003, USA
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9
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Mačková M, Pohl R, Hocek M. Polymerase synthesis of DNAs bearing vinyl groups in the major groove and their cleavage by restriction endonucleases. Chembiochem 2014; 15:2306-12. [PMID: 25179889 DOI: 10.1002/cbic.201402319] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Indexed: 01/12/2023]
Abstract
DNA molecules containing 5-vinyluracil, 5-vinylcytosine, or 7-deaza-7-vinyladenine were prepared by polymerase incorporation of the corresponding vinyl-modified 2'-deoxyribonucleoside triphosphates, and the influence of the vinyl group in the major groove of DNA on the cleavage by diverse type II restriction endonucleases (REs) was studied. The presence of 5-vinyluracil was tolerated by most of the REs, whereas only some REs were able to cleave sequences containing 7-deaza-7-vinyladenine. The enzyme ScaI was found to cleave DNA containing 5-vinylcytosine efficiently but not DNA containing the related 5-ethynylcytosine. All other REs failed to cleave sequences containing any cytosine modifications.
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Affiliation(s)
- Michaela Mačková
- Institute of Organic Chemistry and Biochemistry, Academy of Science Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo nám. 2, 16610 Prague 6 (Czech Republic)
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10
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Andersen JD, Pereira V, Pietroni C, Mikkelsen M, Johansen P, Børsting C, Morling N. Next-generation sequencing of multiple individuals per barcoded library by deconvolution of sequenced amplicons using endonuclease fragment analysis. Biotechniques 2014; 57:91-4. [PMID: 25109295 DOI: 10.2144/000114200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 07/14/2014] [Indexed: 11/23/2022] Open
Abstract
The simultaneous sequencing of samples from multiple individuals increases the efficiency of next-generation sequencing (NGS) while also reducing costs. Here we describe a novel and simple approach for sequencing DNA from multiple individuals per barcode. Our strategy relies on the endonuclease digestion of PCR amplicons prior to library preparation, creating a specific fragment pattern for each individual that can be resolved after sequencing. By using both barcodes and restriction fragment patterns, we demonstrate the ability to sequence the human melanocortin 1 receptor (MC1R) genes from 72 individuals using only 24 barcoded libraries.
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Affiliation(s)
- Jeppe D Andersen
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Vania Pereira
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Carlotta Pietroni
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin Mikkelsen
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peter Johansen
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Claus Børsting
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels Morling
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Little EJ, Dunten PW, Bitinaite J, Horton NC. New clues in the allosteric activation of DNA cleavage by SgrAI: structures of SgrAI bound to cleaved primary-site DNA and uncleaved secondary-site DNA. Acta Crystallogr D Biol Crystallogr 2011; 67:67-74. [PMID: 21206063 PMCID: PMC3016018 DOI: 10.1107/s0907444910047785] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 11/17/2010] [Indexed: 11/10/2022]
Abstract
SgrAI is a type II restriction endonuclease that cuts an unusually long recognition sequence and exhibits allosteric self-activation with expansion of DNA-sequence specificity. The three-dimensional crystal structures of SgrAI bound to cleaved primary-site DNA and Mg²(+) and bound to secondary-site DNA with either Mg²(+) or Ca²(+) are presented. All three structures show a conformation of enzyme and DNA similar to the previously determined dimeric structure of SgrAI bound to uncleaved primary-site DNA and Ca²(+) [Dunten et al. (2008), Nucleic Acids Res. 36, 5405-5416], with the exception of the cleaved bond and a slight shifting of the DNA in the SgrAI/cleaved primary-site DNA/Mg²(+) structure. In addition, a new metal ion binding site is located in one of the two active sites in this structure, which is consistent with proposals for the existence of a metal-ion site near the 3'-O leaving group.
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Affiliation(s)
- Elizabeth J. Little
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Pete W. Dunten
- Stanford Synchrotron Radiation Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | | | - Nancy C. Horton
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
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12
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Mello ML, Chambers AF, Vidal BC, Planding W, Schenck U. Restriction enzyme analysis of DNA methylation in "condensed" chromatin of Ha-ras-transformed NIH 3T3 cells. Anal Cell Pathol 2000; 20:163-71. [PMID: 11205319 PMCID: PMC4618154 DOI: 10.1155/2000/138230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Increased amounts of chromatin condensation (i.e., localized areas of high DNA density, or chromatin higher order packing state) have been described in NIH 3T3 cells transformed with the Ha-ras oncogene. The structural basis for this oncogene-mediated alteration in nuclear organization is unknown. Since DNA methylation is likely to be involved in regulating the nucleosomal level of DNA packaging, we studied the role of DNA methylation in higher-order chromatin organization induced by Ha-ras. CpG-methylated DNA content was estimated in "condensed" chromatin of Ha-ras-transformed NIH 3T3 cell lines which differ in ras expression and ras-induced metastatic ability but present approximately the same values of "condensed" chromatin areas. The question posed was that if DNA methylation were involved with the chromatin higher-order organization induced by Ha-ras in these cell lines, the methylated DNA density in the "condensed" chromatin would also be the same. The DNA evaluation was performed by video image analysis in Feulgen-stained cells previously subjected to treatment with Msp I and Hpa II restriction enzymes, which distinguish between methylated and non-methylated DNA. The amount of methylated CpG sequences not digested by Hpa II in "condensed" chromatin regions was found to vary in the studied ras-transformed cell lines. DNA CpG methylation status is thus suggested not to be involved with the higher order chromatin condensation induced by ras transformation in the mentioned NIH 3T3 cell lines.
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Affiliation(s)
- M L Mello
- Department of Cell Biology, Institute of Biology, UNICAMP, Campinas, SP, Brazil.
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13
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Assaf R, Turgeon D, St-Jacques C, Hamelin C. Endonucléases de restriction: isolement et identification d'une souche d'adénovirus canin de type 1. Can Vet J 1985; 26:209-11. [PMID: 17422549 PMCID: PMC1680088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
For the first time in Quebec, a type 1 canine adenovirus was isolated in cell culture and typed by restriction endonuclease analysis. This virus originated from the internal organs of a young dog killed by a severe respiratory disease without showing any sign of hepatitis.
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14
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Abstract
Several continuous lymphoid cell lines have been established from tumors induced by Herpesvirus saimiri. At least a portion of the viral DNA in the marmoset lymphoid cell line 1670, which does not produce detectable virus, is present as covalently closed circular episomal DNA. The use of restriction endonuclease digestion, transfer to nitrocellulose filters, and hybridization of the virus-specific DNA has produced strong evidence that viral DNA sequences present in total 1670 cell DNA and in isolated episomes are extensively methylated. The restriction endonuclease Hpa II has the same recognition sequence as Msp I but, unlike Msp I, fails to cleave when the C of the C-G dinucleotide is methylated. Viral DNA sequences of 1670 cells are refractory to cleavage by Hpa II but not Msp I; greater than 80% of the Hpa II cleavage sites appear to be methylated. Similarly, viral DNA sequences of 1670 cells are refractory to cleavage by Sma I (C-C-C-G-G-G) and Sac II (C-C-G-C-G-G) but not Sac I, Pvu II, or Pst I, which lack the dinucleotide C-G in their recognition sequences. Methylation of mammalian DNA has been previously found exclusively at C residues in the dinucleotide C-G. H. saimiri DNA sequences of another nonproducer cell line, 70N2, also appeared to be extensively methylated, but analysis of total cell DNA extracted from three virus-producing lymphoid lines revealed no evidence of methylation of viral DNA sequences. It remains to be seen if methylation of viral DNA plays a role in the lack of complete expression of H. saimiri genome information in nonproducing lymphoid cell lines.
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