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Wood WN, Rubio MA, Leiva LE, Phillips GJ, Ibba M. Methionyl-tRNA synthetase synthetic and proofreading activities are determinants of antibiotic persistence. Front Microbiol 2024; 15:1384552. [PMID: 38601944 PMCID: PMC11004401 DOI: 10.3389/fmicb.2024.1384552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 03/12/2024] [Indexed: 04/12/2024] Open
Abstract
Bacterial antibiotic persistence is a phenomenon where bacteria are exposed to an antibiotic and the majority of the population dies while a small subset enters a low metabolic, persistent, state and are able to survive. Once the antibiotic is removed the persistent population can resuscitate and continue growing. Several different molecular mechanisms and pathways have been implicated in this phenomenon. A common mechanism that may underly bacterial antibiotic persistence is perturbations in protein synthesis. To investigate this mechanism, we characterized four distinct metG mutants for their ability to increase antibiotic persistence. Two metG mutants encode changes near the catalytic site of MetRS and the other two mutants changes near the anticodon binding domain. Mutations in metG are of particular interest because MetRS is responsible for aminoacylation both initiator tRNAMet and elongator tRNAMet indicating that these mutants could impact translation initiation and/or translation elongation. We observed that all the metG mutants increased the level of antibiotic persistence as did reduced transcription levels of wild type metG. Although, the MetRS variants did not have an impact on MetRS activity itself, they did reduce translation rates. It was also observed that the MetRS variants affected the proofreading mechanism for homocysteine and that these mutants' growth is hypersensitive to homocysteine. Taken together with previous findings, our data indicate that both reductions in cellular Met-tRNAMet synthetic capacity and reduced proofreading of homocysteine by MetRS variants are positive determinants for bacterial antibiotic persistence.
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Affiliation(s)
- Whitney N. Wood
- Department of Microbiology, The Ohio State University, Columbus, OH, United States
- Schmid College of Science and Technology, Chapman University, Orange, CA, United States
| | - Miguel Angel Rubio
- Department of Microbiology, The Ohio State University, Columbus, OH, United States
| | - Lorenzo Eugenio Leiva
- Schmid College of Science and Technology, Chapman University, Orange, CA, United States
| | - Gregory J. Phillips
- Department of Veterinary Microbiology, Iowa State University, Ames, IA, United States
| | - Michael Ibba
- Department of Microbiology, The Ohio State University, Columbus, OH, United States
- Schmid College of Science and Technology, Chapman University, Orange, CA, United States
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Arroyo-Mendoza M, Proctor A, Correa-Medina A, Brand MW, Rosas V, Wannemuehler MJ, Phillips GJ, Hinton DM. The E. coli pathobiont LF82 encodes a unique variant of σ 70 that results in specific gene expression changes and altered phenotypes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.08.523653. [PMID: 36798310 PMCID: PMC9934711 DOI: 10.1101/2023.02.08.523653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
LF82, an adherent invasive Escherichia coli pathobiont, is associated with ileal Crohn's disease, an inflammatory bowel disease of unknown etiology. Although LF82 contains no virulence genes, it carries several genetic differences, including single nucleotide polymorphisms (SNPs), that distinguish it from nonpathogenic E. coli. We have identified and investigated an extremely rare SNP that is within the highly conserved rpoD gene, encoding σ70, the primary sigma factor for RNA polymerase. We demonstrate that this single residue change (D445V) results in specific transcriptome and phenotypic changes that are consistent with multiple phenotypes observed in LF82, including increased antibiotic resistance and biofilm formation, modulation of motility, and increased capacity for methionine biosynthesis. Our work demonstrates that a single residue change within the bacterial primary sigma factor can lead to multiple alterations in gene expression and phenotypic changes, suggesting an underrecognized mechanism by which pathobionts and other strain variants with new phenotypes can emerge.
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Affiliation(s)
- Melissa Arroyo-Mendoza
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 8 Center Dr., Bethesda, MD, United States, 20892
- Department of Veterinary Microbiology and Preventative Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States, 50011
| | - Alexandra Proctor
- Department of Veterinary Microbiology and Preventative Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States, 50011
| | - Abraham Correa-Medina
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 8 Center Dr., Bethesda, MD, United States, 20892
| | - Meghan Wymore Brand
- Department of Veterinary Microbiology and Preventative Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States, 50011
| | - Virginia Rosas
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 8 Center Dr., Bethesda, MD, United States, 20892
| | - Michael J Wannemuehler
- Department of Veterinary Microbiology and Preventative Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States, 50011
| | - Gregory J Phillips
- Department of Veterinary Microbiology and Preventative Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States, 50011
| | - Deborah M Hinton
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 8 Center Dr., Bethesda, MD, United States, 20892
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Zhao Y, Han J, Tan J, Yang Y, Li S, Gou Y, Luo Y, Li T, Xiao W, Xue Y, Hao Y, Xie X, Liu Y, Zhu Q. Efficient assembly of long DNA fragments and multiple genes with improved nickase-based cloning and Cre/loxP recombination. PLANT BIOTECHNOLOGY JOURNAL 2022; 20:1983-1995. [PMID: 35767383 PMCID: PMC9491458 DOI: 10.1111/pbi.13882] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 06/14/2022] [Accepted: 06/22/2022] [Indexed: 06/15/2023]
Abstract
Functional genomics, synthetic biology and metabolic engineering require efficient tools to deliver long DNA fragments or multiple gene constructs. Although numerous DNA assembly methods exist, most are complicated, time-consuming and expensive. Here, we developed a simple and flexible strategy, unique nucleotide sequence-guided nicking endonuclease (UNiE)-mediated DNA assembly (UNiEDA), for efficient cloning of long DNAs and multigene stacking. In this system, a set of unique 15-nt 3' single-strand overhangs were designed and produced by nicking endonucleases (nickases) in vectors and insert sequences. We introduced UNiEDA into our modified Cre/loxP recombination-mediated TransGene Stacking II (TGSII) system to generate an improved multigene stacking system we call TGSII-UNiE. Using TGSII-UNiE, we achieved efficient cloning of long DNA fragments of different sizes and assembly of multiple gene cassettes. Finally, we engineered and validated the biosynthesis of betanin in wild tobacco (Nicotiana benthamiana) leaves and transgenic rice (Oryza sativa) using multigene stacking constructs based on TGSII-UNiE. In conclusion, UNiEDA is an efficient, convenient and low-cost method for DNA cloning and multigene stacking, and the TGSII-UNiE system has important application prospects for plant functional genomics, genetic engineering and synthetic biology research.
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Affiliation(s)
- Yanchang Zhao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- Guangdong Laboratory for Lingnan Modern AgricultureGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Jingluan Han
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- Guangdong Laboratory for Lingnan Modern AgricultureGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Jiantao Tan
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- Guangdong Laboratory for Lingnan Modern AgricultureGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Yaqian Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Shuangchun Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Yajun Gou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Yuyu Luo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Tie Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Wenyu Xiao
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Yang Xue
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Yu Hao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Xianrong Xie
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- Guangdong Laboratory for Lingnan Modern AgricultureGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Yao‐Guang Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- Guangdong Laboratory for Lingnan Modern AgricultureGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
| | - Qinlong Zhu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐BioresourcesSouth China Agricultural UniversityGuangzhouChina
- Guangdong Laboratory for Lingnan Modern AgricultureGuangzhouChina
- College of Life SciencesSouth China Agricultural UniversityGuangzhouChina
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Wu P, Li X, Yang M, Huang Z, Mo H, Li T, Zhang Y, Li H. High-throughput, one-step screening, cloning and expression based on the lethality of DpnI in Escherichia coli. Biochem Biophys Res Commun 2018; 504:177-183. [PMID: 30172375 DOI: 10.1016/j.bbrc.2018.08.151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 08/25/2018] [Indexed: 11/17/2022]
Abstract
The manipulation of recombinant DNA has been an integral step in molecular biology to date. A number of strategies have been developed over the years, as traditional cloning methods are time consuming, have high backgrounds and low efficiency and are often limited by the number of suitable restriction sites available. Here, we constructed a series of new positive-selection-based cloning vectors that overcome most of the above mentioned drawbacks and can be applied in both eukaryotic and prokaryotic systems. This strategy is based on the extreme toxicity of DpnI in wild-type E. coli and the inactivation of this lethality by the introduction of target gene within multiple cloning sites. There are no rapid approaches for identifying soluble proteins for high-throughput screening. In this study, we combined this highly efficient cloning strategy with rapid identification of soluble proteins to construct vectors with multiple fusion tags, such as MBP, GST, CBD, NusA, and Sumo, to generate enzymes with potential diagnostic, industrial or therapeutic applications. Thus, this versatile positive-selection-based technology is appropriate for routine cloning, DNA library construction, and high-throughput screening for the expression of proteins of interest.
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Affiliation(s)
- Peijie Wu
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China
| | - Xiaoyan Li
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China
| | - Maocheng Yang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China
| | - Zhengzhi Huang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China
| | - Hongya Mo
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China
| | - Ting Li
- Chinese Academy of Inspection and Quarantine, China
| | - Yuan Zhang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China
| | - Hongtao Li
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China.
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5
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Ramos AE, Muñoz M, Moreno-Pérez DA, Patarroyo MA. pELMO, an optimised in-house cloning vector. AMB Express 2017; 7:26. [PMID: 28116699 PMCID: PMC5265227 DOI: 10.1186/s13568-017-0324-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 01/02/2017] [Indexed: 11/18/2022] Open
Abstract
DNA cloning is an essential tool regarding DNA recombinant technology as it allows the replication of foreign DNA fragments within a cell. pELMO was here constructed as an in-house cloning vector for rapid and low-cost PCR product propagation; it is an optimally designed vector containing the ccdB killer gene from the pDONR 221 plasmid, cloned into the pUC18 vector’s multiple cloning site (Thermo Scientific). The ccdB killer gene has a cleavage site (CCC/GGG) for the SmaI restriction enzyme which is used for vector linearisation and cloning blunt-ended products. pELMO transformation efficiency was evaluated with different sized inserts and its cloning efficiency was compared to that of the pGEM-T Easy commercial vector. The highest pELMO transformation efficiency was observed for ~500 bp DNA fragments; pELMO vector had higher cloning efficiency for all insert sizes tested. In-house and commercial vector cloned insert reads after sequencing were similar thus highlighting that sequencing primers were designed and localised appropriately. pELMO is thus proposed as a practical alternative for in-house cloning of PCR products in molecular biology laboratories.
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VanDrisse CM, Escalante-Semerena JC. New high-cloning-efficiency vectors for complementation studies and recombinant protein overproduction in Escherichia coli and Salmonella enterica. Plasmid 2016; 86:1-6. [PMID: 27234933 PMCID: PMC5126758 DOI: 10.1016/j.plasmid.2016.05.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/16/2016] [Accepted: 05/23/2016] [Indexed: 11/23/2022]
Abstract
Galloway et al. recently described a method to alter vectors to include Type IIS restriction enzymes for high efficiency cloning. Utilizing this method, the multiple cloning sites of complementation and overexpression vectors commonly used in our laboratory were altered to contain recognition sequences of the Type IIS restriction enzyme, BspQI. Use of this enzyme increased the rate of cloning success to >97% efficiency. L(+)-Arabinose-inducible complementation vectors and overexpression vectors encoding N-terminal recombinant tobacco etch virus protease (rTEV)-cleavable H6-tags were altered to contain BspQI sites that allowed for cloning into all vectors using identical primer overhangs. Additionally, a vector used for directing the synthesis of proteins with a C-terminal, rTEV-cleavable H6-tag was engineered to contain BspQI sites, albeit with different overhangs from that of the previously mentioned vectors. Here we apply a method used to engineer cloning vectors to contain BspQI sites and the use of each vector in either in vivo complementation studies or in vitro protein purifications.
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Affiliation(s)
- C M VanDrisse
- Department of Microbiology, University of, 120 Cedar Street, Athens, GA 306022605 Georgia
| | - J C Escalante-Semerena
- Department of Microbiology, University of, 120 Cedar Street, Athens, GA 306022605 Georgia.
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Xu SY. Sequence-specific DNA nicking endonucleases. Biomol Concepts 2016; 6:253-67. [PMID: 26352356 DOI: 10.1515/bmc-2015-0016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 06/24/2015] [Indexed: 01/17/2023] Open
Abstract
A group of small HNH nicking endonucleases (NEases) was discovered recently from phage or prophage genomes that nick double-stranded DNA sites ranging from 3 to 5 bp in the presence of Mg2+ or Mn2+. The cosN site of phage HK97 contains a gp74 nicking site AC↑CGC, which is similar to AC↑CGR (R=A/G) of N.ϕGamma encoded by Bacillus phage Gamma. A minimal nicking domain of 76 amino acid residues from N.ϕGamma could be fused to other DNA binding partners to generate chimeric NEases with new specificities. The biological roles of a few small HNH endonucleases (HNHE, gp74 of HK97, gp37 of ϕSLT, ϕ12 HNHE) have been demonstrated in phage and pathogenicity island DNA packaging. Another group of NEases with 3- to 7-bp specificities are either natural components of restriction systems or engineered from type IIS restriction endonucleases. A phage group I intron-encoded HNH homing endonucleases, I-PfoP3I was found to nick DNA sites of 14-16 bp. I-TslI encoded by T7-like ΦI appeared to nick DNA sites with a 9-bp core sequence. DNA nicking and labeling have been applied to optical mapping to aid genome sequence assembly and detection of large insertion/deletion mutations in genomic DNA of cancer cells. Nicking enzyme-mediated amplification reaction has been applied to rapid diagnostic testing of influenza A and B in clinical setting and for construction of DNA-based Boolean logic gates. The clustered regularly interspaced short palindromic repeats-ribonucleoprotein complex consisting of engineered Cas9 nickases in conjunction with tracerRNA:crRNA or a single-guide RNA have been successfully used in genome modifications.
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Ma Z, Luo D, Huang A, Xu Y, Wang Y, Wei Y, Liang P. pKILLIN: a versatile positive-selection cloning vector based on the toxicity of Killin in Escherichia coli. Gene 2014; 544:228-35. [PMID: 24768186 DOI: 10.1016/j.gene.2014.04.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 04/16/2014] [Accepted: 04/19/2014] [Indexed: 11/26/2022]
Abstract
The invention of DNA cloning over 40 years ago marked the advent of molecular biology. The technique has now become a routine practice in any modern biomedical laboratory. Although positive-selection of recombinants in DNA cloning seems to be superior to blue/white selection based on the disruption of the lacZ gene, it is rarely practiced due to its high background, lack of multiple cloning sites, and inability to express the genes of interest or purify the protein products. Here we report the creation of a new positive-selection cloning vector dubbed pKILLIN, which overcomes all of the above pitfalls. The essence behind its high cloning efficiency is the extreme toxicity and small size of the toxic domain of killin, a recently discovered p53 target gene. Insertion inactivation of killin within the multiple cloning site via either blunt- or sticky-end ligation not only serves as a highly efficient cloning trap, but also may allow any cloned genes to be expressed as His-tagged fusion proteins for subsequent purification. Thus, pKILLIN is a versatile positive-selection vector ideal for cloning PCR products, making DNA libraries, as well as routine cloning and bacterial expression of genes.
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Affiliation(s)
- Zelong Ma
- Center for Growth, Metabolism and Aging, School of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Dan Luo
- Center for Growth, Metabolism and Aging, School of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Anliang Huang
- State Key Laboratory for Gene and Cell Therapy, Sichuan University, Chengdu, China
| | - Yang Xu
- Center for Growth, Metabolism and Aging, School of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Yunxiao Wang
- Clover Biopharmaceuticals, Chengdu, China; State Key Laboratory for Gene and Cell Therapy, Sichuan University, Chengdu, China
| | - Yuquan Wei
- State Key Laboratory for Gene and Cell Therapy, Sichuan University, Chengdu, China
| | - Peng Liang
- Center for Growth, Metabolism and Aging, School of Life Sciences, Sichuan University, Chengdu 610064, China; Clover Biopharmaceuticals, Chengdu, China; State Key Laboratory for Gene and Cell Therapy, Sichuan University, Chengdu, China; GenHunter Corporation, 624 Grassmere Park, Nashville, TN 37211, USA.
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Gutjahr A, Xu SY. Engineering nicking enzymes that preferentially nick 5-methylcytosine-modified DNA. Nucleic Acids Res 2014; 42:e77. [PMID: 24609382 PMCID: PMC4027164 DOI: 10.1093/nar/gku192] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
N.ϕGamma is a strand-specific and site-specific DNA nicking enzyme (YCG↓GT or AC↑CGR). Here we describe the isolation of single and double mutants of N.ϕGamma with attenuated activity. The nicking domains (NDs) of E59A and 11 double mutants were fused to the 5mCG-binding domain of MBD2 and generated fusion enzymes that preferentially nick 5mCG-modified DNA. The CG dinucleotide can be modified by C5 methyltransferases (MTases) such as M.SssI, M.HhaI or M.HpaII to create composite sites AC↑YGG N(8-15) 5mCG. We also constructed a fusion enzyme 2xMBD2-ND(N.BceSVIII) targeting more frequent composite sites AS↑YS N(5-12) 5mCG in Mn2+ buffer. 5mCG-dependent nicking requires special digestion conditions in high salt (0.3 M KCl) or in Ni2+ buffer. The fusion enzyme can be used to nick and label 5mCG-modified plasmid and genomic DNAs with fluorescently labeled Cy3-dUTP and potentially be useful for diagnostic applications, DNA sequencing and optical mapping of epigenetic markers. The importance of the predicted catalytic residues D89, H90, N106 and H115 in N.ϕGamma was confirmed by mutagenesis. We found that the wild-type enzyme N.ϕGamma prefers to nick 5mCG-modified DNA in Ni2+ buffer even though the nicking activity is sub-optimal compared to the activity in Mg2+ buffer.
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Affiliation(s)
- Alice Gutjahr
- New England Biolabs, Inc., 240 County Road, Ipswich, MA 01938, USA
| | - Shuang-yong Xu
- New England Biolabs, Inc., 240 County Road, Ipswich, MA 01938, USA
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