1
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Chen S, Yang Z, Zhong Z, Yu S, Zhou J, Li J, Du G, Zhang G. Ultrahigh-throughput screening-assisted in vivo directed evolution for enzyme engineering. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:9. [PMID: 38254175 PMCID: PMC10804518 DOI: 10.1186/s13068-024-02457-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 01/05/2024] [Indexed: 01/24/2024]
Abstract
BACKGROUND Classical directed evolution is a powerful approach for engineering biomolecules with improved or novel functions. However, it traditionally relies on labour- and time-intensive iterative cycles, due in part to the need for multiple molecular biology steps, including DNA transformation, and limited screening throughput. RESULTS In this study, we present an ultrahigh throughput in vivo continuous directed evolution system with thermosensitive inducible tunability, which is based on error-prone DNA polymerase expression modulated by engineered thermal-responsive repressor cI857, and genomic MutS mutant with temperature-sensitive defect for fixation of mutations in Escherichia coli. We demonstrated the success of the in vivo evolution platform with β-lactamase as a model, with an approximately 600-fold increase in the targeted mutation rate. Furthermore, the platform was combined with ultrahigh-throughput screening methods and employed to evolve α-amylase and the resveratrol biosynthetic pathway. After iterative rounds of enrichment, a mutant with a 48.3% improvement in α-amylase activity was identified via microfluidic droplet screening. In addition, when coupled with an in vivo biosensor in the resveratrol biosynthetic pathway, a variant with 1.7-fold higher resveratrol production was selected by fluorescence-activated cell sorting. CONCLUSIONS In this study, thermal-responsive targeted mutagenesis coupled with ultrahigh-throughput screening was developed for the rapid evolution of enzymes and biosynthetic pathways.
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Affiliation(s)
- Shuaili Chen
- Science Center for Future Foods, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Zhanhao Yang
- Science Center for Future Foods, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Ze Zhong
- Science Center for Future Foods, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Shiqin Yu
- Science Center for Future Foods, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Jingwen Zhou
- Science Center for Future Foods, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
- Engineering Research Center of Ministry of Education On Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Jianghua Li
- Science Center for Future Foods, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
- Engineering Research Center of Ministry of Education On Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Guocheng Du
- Science Center for Future Foods, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
- Engineering Research Center of Ministry of Education On Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
| | - Guoqiang Zhang
- Science Center for Future Foods, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
- Engineering Research Center of Ministry of Education On Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
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2
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Feng S, Liang L, Shen C, Lin D, Li J, Lyu L, Liang W, Zhong LL, Cook GM, Doi Y, Chen C, Tian GB. A CRISPR-guided mutagenic DNA polymerase strategy for the detection of antibiotic-resistant mutations in M. tuberculosis. MOLECULAR THERAPY - NUCLEIC ACIDS 2022; 29:354-367. [PMID: 35950213 PMCID: PMC9358013 DOI: 10.1016/j.omtn.2022.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 07/08/2022] [Indexed: 11/26/2022]
Abstract
A sharp increase in multidrug-resistant tuberculosis (MDR-TB) threatens human health. Spontaneous mutation in essential gene confers an ability of Mycobacterium tuberculosis resistance to anti-TB drugs. However, conventional laboratory strategies for identification and prediction of the mutations in this slowly growing species remain challenging. Here, by combining XCas9 nickase and the error-prone DNA polymerase A from M. tuberculosis, we constructed a CRISPR-guided DNA polymerase system, CAMPER, for effective site-directed mutagenesis of drug-target genes in mycobacteria. CAMPER was able to generate mutagenesis of all nucleotides at user-defined loci, and its bidirectional mutagenesis at nick sites allowed editing windows with lengths up to 80 nucleotides. Mutagenesis of drug-targeted genes in Mycobacterium smegmatis and M. tuberculosis with this system significantly increased the fraction of the antibiotic-resistant bacterial population to a level approximately 60- to 120-fold higher than that in unedited cells. Moreover, this strategy could facilitate the discovery of the mutation conferring antibiotic resistance and enable a rapid verification of the growth phenotype-mutation genotype association. Our data demonstrate that CAMPER facilitates targeted mutagenesis of genomic loci and thus may be useful for broad functions such as resistance prediction and development of novel TB therapies.
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3
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McLure RJ, Radford SE, Brockwell DJ. High-throughput directed evolution: a golden era for protein science. TRENDS IN CHEMISTRY 2022. [DOI: 10.1016/j.trechm.2022.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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4
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Evseev P, Lukianova A, Tarakanov R, Tokmakova A, Shneider M, Ignatov A, Miroshnikov K. Curtobacterium spp. and Curtobacterium flaccumfaciens: Phylogeny, Genomics-Based Taxonomy, Pathogenicity, and Diagnostics. Curr Issues Mol Biol 2022; 44:889-927. [PMID: 35723345 PMCID: PMC8929003 DOI: 10.3390/cimb44020060] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/19/2022] [Accepted: 02/08/2022] [Indexed: 11/29/2022] Open
Abstract
The genus of Curtobacterium, belonging to the Microbacteriaceae family of the Actinomycetales order, includes economically significant pathogenic bacteria of soybeans and other agricultural crops. Thorough phylogenetic and full-genome analysis using the latest genomic data has demonstrated a complex and contradictory taxonomic picture within the group of organisms classified as the Curtobacterium species. Based on these data, it is possible to delineate about 50 new species and to reclassify a substantial part of the Curtobacterium strains. It is suggested that 53 strains, including most of the Curtobacterium flaccumfaciens pathovars, can compose a monophyletic group classified as C. flaccumfaciens. A genomic analysis using the most recent inventory of bacterial chromosomal and plasmid genomes deposited to GenBank confirmed the possible role of Microbacteriaceae plasmids in pathogenicity and demonstrated the existence of a group of related plasmids carrying virulence factors and possessing a gene distantly related to DNA polymerase found in bacteriophages and archaeal and eukaryotic viruses. A PCR diagnostic assay specific to the genus Curtobacterium was developed and tested. The presented results assist in the understanding of the evolutionary relations within the genus and can lay the foundation for further taxonomic updates.
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Affiliation(s)
- Peter Evseev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str., 16/10, 117997 Moscow, Russia; (A.L.); (A.T.); (M.S.)
- Limnological Institute, Siberian Branch of Russian Academy of Sciences, Ulan-Batorskaya Str., 3, 664033 Irkutsk, Russia
- Correspondence: (P.E.); (K.M.)
| | - Anna Lukianova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str., 16/10, 117997 Moscow, Russia; (A.L.); (A.T.); (M.S.)
| | - Rashit Tarakanov
- Department of Plant Protection, Russian State Agrarian University—Moscow Timiryazev Agricultural Academy, Timiryazevskaya Str., 49, 127434 Moscow, Russia;
| | - Anna Tokmakova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str., 16/10, 117997 Moscow, Russia; (A.L.); (A.T.); (M.S.)
- Moscow Institute of Physics and Technology, Federal University, Institutskiy per., 9, 141701 Dolgoprudny, Moscow Oblast, Russia
| | - Mikhail Shneider
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str., 16/10, 117997 Moscow, Russia; (A.L.); (A.T.); (M.S.)
| | - Alexander Ignatov
- Agrobiotechnology Department, Agrarian and Technological Institute, RUDN University, Miklukho-Maklaya Str., 6, 117198 Moscow, Russia;
| | - Konstantin Miroshnikov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str., 16/10, 117997 Moscow, Russia; (A.L.); (A.T.); (M.S.)
- Correspondence: (P.E.); (K.M.)
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5
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Zhang Y, Ding W, Wang Z, Zhao H, Shi S. Development of Host-Orthogonal Genetic Systems for Synthetic Biology. Adv Biol (Weinh) 2021; 5:e2000252. [PMID: 33729696 DOI: 10.1002/adbi.202000252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/18/2020] [Indexed: 12/17/2022]
Abstract
The construction of a host-orthogonal genetic system can not only minimize the impact of host-specific nuances on fine-tuning of gene expression, but also expand cellular functions such as in vivo continuous evolution of genes based on an error-prone DNA polymerase. It represents an emerging powerful approach for making biology easier to engineer. In this review, the recent advances are described on the design of genetic systems that can be stably inherited in the host cells and are responsible for important biological processes including DNA replication, RNA transcription, protein translation, and gene regulation. Their applications in synthetic biology are summarized and the future challenges and opportunities are discussed in developing such systems.
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Affiliation(s)
- Yang Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Wentao Ding
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.,Key Laboratory of Food Nutrition and Safety (Tianjin University of Science and Technology) Ministry of Education, College of Food Engineering and Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, TEDA, Tianjin, 300457, P. R. China
| | - Zhihui Wang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Shuobo Shi
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
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6
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Pérez-Arnaiz P, Dattani A, Smith V, Allers T. Haloferax volcanii-a model archaeon for studying DNA replication and repair. Open Biol 2020; 10:200293. [PMID: 33259746 PMCID: PMC7776575 DOI: 10.1098/rsob.200293] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/09/2020] [Indexed: 12/16/2022] Open
Abstract
The tree of life shows the relationship between all organisms based on their common ancestry. Until 1977, it comprised two major branches: prokaryotes and eukaryotes. Work by Carl Woese and other microbiologists led to the recategorization of prokaryotes and the proposal of three primary domains: Eukarya, Bacteria and Archaea. Microbiological, genetic and biochemical techniques were then needed to study the third domain of life. Haloferax volcanii, a halophilic species belonging to the phylum Euryarchaeota, has provided many useful tools to study Archaea, including easy culturing methods, genetic manipulation and phenotypic screening. This review will focus on DNA replication and DNA repair pathways in H. volcanii, how this work has advanced our knowledge of archaeal cellular biology, and how it may deepen our understanding of bacterial and eukaryotic processes.
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Affiliation(s)
| | | | | | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK
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7
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Brödel AK, Rodrigues R, Jaramillo A, Isalan M. Accelerated evolution of a minimal 63-amino acid dual transcription factor. SCIENCE ADVANCES 2020; 6:eaba2728. [PMID: 32577520 PMCID: PMC7286687 DOI: 10.1126/sciadv.aba2728] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 04/14/2020] [Indexed: 05/13/2023]
Abstract
Transcription factors control gene expression in all life. This raises the question of what is the smallest protein that can support such activity. In nature, Cro from bacteriophage λ is one of the smallest known repressors (66 amino acids), and activators are typically much larger (e.g., λ cI, 237 amino acids). Previous efforts to engineer a minimal activator from λ Cro resulted in no activity in vivo in cells. In this study, we show that directed evolution results in a new Cro activator-repressor that functions as efficiently as λ cI in vivo. To achieve this, we develop phagemid-assisted continuous evolution (PACEmid). We find that a peptide as small as 63 amino acids functions efficiently as an activator and/or repressor. To our knowledge, this is the smallest protein activator that enables polymerase recruitment, highlighting the capacity of transcription factors to evolve from very short peptide sequences.
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Affiliation(s)
- Andreas K. Brödel
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Rui Rodrigues
- Warwick Integrative Synthetic Biology Centre and School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Alfonso Jaramillo
- Warwick Integrative Synthetic Biology Centre and School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
- CNRS-UMR8030, Laboratoire iSSB and Université Paris-Saclay and Université d’Évry and CEA, DRF, IG, Genoscope, Évry 91000, France
- Institute for Integrative Systems Biology (I2SysBio), University of Valencia-CSIC, 46980 Paterna, Spain
| | - Mark Isalan
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
- Corresponding author.
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8
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Moore CL, Papa LJ, Shoulders MD. A Processive Protein Chimera Introduces Mutations across Defined DNA Regions In Vivo. J Am Chem Soc 2018; 140:11560-11564. [PMID: 29991261 PMCID: PMC6166643 DOI: 10.1021/jacs.8b04001] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Laboratory time scale evolution in vivo relies on the generation of large, mutationally diverse gene libraries to rapidly explore biomolecule sequence landscapes. Traditional global mutagenesis methods are problematic because they introduce many off-target mutations that are often lethal and can engender false positives. We report the development and application of the MutaT7 chimera, a potent and highly targeted in vivo mutagenesis agent. MutaT7 utilizes a DNA-damaging cytidine deaminase fused to a processive RNA polymerase to continuously direct mutations to specific, well-defined DNA regions of any relevant length. MutaT7 thus provides a mechanism for in vivo targeted mutagenesis across multi-kb DNA sequences. MutaT7 should prove useful in diverse organisms, opening the door to new types of in vivo evolution experiments.
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Affiliation(s)
- Christopher L Moore
- Department of Chemistry , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
| | - Louis J Papa
- Department of Chemistry , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
| | - Matthew D Shoulders
- Department of Chemistry , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
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9
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Standley M, Allen J, Cervantes L, Lilly J, Camps M. Fluorescence-Based Reporters for Detection of Mutagenesis in E. coli. Methods Enzymol 2017. [PMID: 28645368 DOI: 10.1016/bs.mie.2017.03.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Mutagenesis in model organisms following exposure to chemicals is used as an indicator of genotoxicity. Mutagenesis assays are also used to study mechanisms of DNA homeostasis. This chapter focuses on detection of mutagenesis in prokaryotes, which boils down to two approaches: reporter inactivation (forward mutation assay) and reversion of an inactivating mutation (reversion mutation assay). Both methods are labor intensive, involving visual screening, quantification of colonies on solid media, or determining a Poisson distribution in liquid culture. Here, we present two reversion reporters for in vivo mutagenesis that produce a quantitative output, and thus have the potential to greatly reduce the amount of test chemical and labor involved in these assays. This output is obtained by coupling a TEM β lactamase-based reversion assay with GFP fluorescence, either by placing the two genes on the same plasmid or by fusing them translationally and interrupting the N-terminus of the chimeric ORF with a stop codon. We also describe a reporter aimed at facilitating the monitoring of continuous mutagenesis in mutator strains. This reporter couples two reversion markers, allowing the temporal separation of mutation events in time, thus providing information about the dynamics of mutagenesis in mutator strains. Here, we describe these reporter systems, provide protocols for use, and demonstrate their key functional features using error-prone Pol I mutagenesis as a source of mutations.
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Affiliation(s)
- Melissa Standley
- University of California-Santa Cruz, Santa Cruz, CA, United States
| | - Jennifer Allen
- University of California-Santa Cruz, Santa Cruz, CA, United States
| | - Layla Cervantes
- University of California-Santa Cruz, Santa Cruz, CA, United States
| | - Joshua Lilly
- University of California-Santa Cruz, Santa Cruz, CA, United States
| | - Manel Camps
- University of California-Santa Cruz, Santa Cruz, CA, United States.
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10
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Zheng X, Xing XH, Zhang C. Targeted mutagenesis: A sniper-like diversity generator in microbial engineering. Synth Syst Biotechnol 2017; 2:75-86. [PMID: 29062964 PMCID: PMC5636951 DOI: 10.1016/j.synbio.2017.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 06/30/2017] [Accepted: 07/03/2017] [Indexed: 12/26/2022] Open
Abstract
Mutations, serving as the raw materials of evolution, have been extensively utilized to increase the chances of engineering molecules or microbes with tailor-made functions. Global and targeted mutagenesis are two main methods of obtaining various mutations, distinguished by the range of action they can cover. While the former one stresses the mining of novel genetic loci within the whole genomic background, targeted mutagenesis performs in a more straightforward manner, bringing evolutionary escape and error catastrophe under control. In this review, we classify the existing techniques of targeted mutagenesis into two categories in terms of whether the diversity is generated in vitro or in vivo, and briefly introduce the mechanisms and applications of them separately. The inherent connections and development trends of the two classes are also discussed to provide an insight into the next generation evolution research.
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Key Words
- 3′-LTR, 3’-long terminal repeat
- 5-FOA, 5-fluoro-orotic acid
- CRISPR/Cas9, clustered regularly interspaced short palindromic repeats and associated protein 9
- DNA Pol III, DNA polymerase III
- DNA PolI, DNA polymerase I
- DSB, double strand break
- Evolution
- FLASH, fast ligation-based automatable solid-phase high-throughput
- HDR, homology-directed repair
- HIV, human immunodeficiency virus
- ICE, in vivo continuous evolution
- LIC, ligation-independent cloning
- MAGE, multiplex automated genome engineering
- MMEJ, microhomology-mediated end-joining
- Mutations
- NHEJ, error-prone non-homologous end-joining
- ORF, open reading frame
- PAM, protospacer-adjacent motif
- RVD, repeat variable di-residue
- Synthetic biology
- TALE, transcription activator-like effector
- TALEN, transcription activator-like effector nuclease
- TP, terminal protein
- TP-DNAP, TP-DNA polymerase fusion
- TaGTEAM, targeting glycosylase to embedded arrays for mutagenesis
- Targeted mutagenesis
- YOGE, yeast oligo-mediated genome engineering
- ZF, zinc-finger protein
- ZFN, zinc-finger nuclease
- dCas9, catalytically dead Cas9
- dNTP, deoxy-ribonucleoside triphosphate
- dsDNA, double-stranded DNA
- error-prone PCR, error-prone polymerase chain reaction
- non-GMO, non-genetically modified organism
- pre-crRNA, pre-CRISPR RNA
- sctetR, single chain tetR
- sgRNA, single-guide RNA
- ssDNA, single-stranded DNA
- tracrRNA, trans-encoded RNA
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Affiliation(s)
| | | | - Chong Zhang
- Key Laboratory for Industrial Biocatalysis, Ministry of Education, Institute of Biochemical Engineering, Department of Chemical Engineering, Center for Synthetic & Systems Biology, Tsinghua University, Beijing 100084, China
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11
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Abstract
Plasmids are autonomously replicating pieces of DNA. This article discusses theta plasmid replication, which is a class of circular plasmid replication that includes ColE1-like origins of replication popular with expression vectors. All modalities of theta plasmid replication initiate synthesis with the leading strand at a predetermined site and complete replication through recruitment of the host's replisome, which extends the leading strand continuously while synthesizing the lagging strand discontinuously. There are clear differences between different modalities of theta plasmid replication in mechanisms of DNA duplex melting and in priming of leading- and lagging-strand synthesis. In some replicons duplex melting depends on transcription, while other replicons rely on plasmid-encoded trans-acting proteins (Reps); primers for leading-strand synthesis can be generated through processing of a transcript or in other replicons by the action of host- or plasmid-encoded primases. None of these processes require DNA breaks. The frequency of replication initiation is tightly regulated to facilitate establishment in permissive hosts and to achieve a steady state. The last section of the article reviews how plasmid copy number is sensed and how this feedback modulates the frequency of replication.
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12
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Lilly J, Camps M. Mechanisms of Theta Plasmid Replication. Microbiol Spectr 2015; 3:PLAS-0029-2014. [PMID: 26005599 PMCID: PMC4441207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
Plasmids are autonomously replicating pieces of DNA. This chapter discusses theta plasmid replication, which is class of circular plasmid replication that includes ColE1-like origins of replication popular with expression vectors. All modalities of theta plasmid replication initiate synthesis with the leading-strand at a pre-determined site and complete replication through recruitment of the host's replisome, which extends the leading-strand continuously while synthesizing the lagging-strand discontinuously. There are clear differences between different modalities of theta plasmid replication in mechanisms of DNA duplex melting and in priming of leading- and lagging-strand synthesis. In some replicons duplex melting depends on transcription, while other replicons rely on plasmid-encoded trans-acting proteins (Reps); primers for leading-strand synthesis can be generated through processing of a transcript or in other replicons by the action of host- or plasmid-encoded primases. None of these processes require DNA breaks. The frequency of replication initiation is tightly regulated to facilitate establishment in permissive hosts and to achieve a steady state. The last section of the chapter reviews how plasmid copy number is sensed and how this feedback modulates the frequency of replication.
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Affiliation(s)
- Joshua Lilly
- Department of Microbiology and Environmental Toxicology, UC Santa Cruz, 1156 High Street, Santa Cruz, CA 95064
| | - Manel Camps
- Department of Microbiology and Environmental Toxicology, UC Santa Cruz, 1156 High Street, Santa Cruz, CA 95064
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13
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Plasmid-Mediated Antibiotic Resistance and Virulence in Gram-negatives: the Klebsiella pneumoniae Paradigm. Microbiol Spectr 2014; 2:1-15. [PMID: 25705573 DOI: 10.1128/microbiolspec.plas-0016-2013] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Plasmids harbor genes coding for specific functions including virulence factors and antibiotic resistance that permit bacteria to survive the hostile environment found in the host and resist treatment. Together with other genetic elements such as integrons and transposons, and using a variety of mechanisms, plasmids participate in the dissemination of these traits resulting in the virtual elimination of barriers among different kinds of bacteria. In this article we review the current information about physiology and role in virulence and antibiotic resistance of plasmids from the gram-negative opportunistic pathogen Klebsiella pneumoniae. This bacterium has acquired multidrug resistance and is the causative agent of serious communityand hospital-acquired infections. It is also included in the recently defined ESKAPE group of bacteria that cause most of US hospital infections.
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14
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Abstract
A semi-synthetic organism with an extended genetic alphabet heralds a new era in synthetic biology.
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Affiliation(s)
- Roy D Sleator
- Department of Biological Sciences; Cork Institute of Technology; Cork, Ireland
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15
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Malyshev DA, Dhami K, Lavergne T, Chen T, Dai N, Foster JM, Corrêa IR, Romesberg FE. A semi-synthetic organism with an expanded genetic alphabet. Nature 2014; 509:385-8. [PMID: 24805238 PMCID: PMC4058825 DOI: 10.1038/nature13314] [Citation(s) in RCA: 389] [Impact Index Per Article: 38.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 04/08/2014] [Indexed: 02/07/2023]
Abstract
Organisms are defined by the information encoded in their genomes, and since the evolution of life, this information has been encoded using a two base pair genetic alphabet (A-T and G-C). In vitro, the alphabet has been expanded to include several unnatural base pairs (UBPs)1–3. We have developed a class of UBPs formed between nucleotides bearing hydrophobic nucleobases, exemplified by the pair formed between d5SICS and dNaM (d5SICS-dNaM, Fig. 1a), which is efficiently PCR amplified1 and transcribed4,5in vitro, and whose unique mechanism of replication has been characterized6,7. However, expansion of a organism’s genetic alphabet presents new and unprecedented challenges: the unnatural nucleoside triphosphates must enter the cell; endogenous polymerases must be able to faithfully incorporate the unnatural triphosphates into DNA within the complex cellular milieu; and finally, the UBP must be stable in the presence of pathways that maintain the integrity of DNA. Here we show that an exogenously expressed algal nucleotide triphosphate transporter efficiently imports the triphosphates of both d5SICS and dNaM (d5SICSTP and dNaMTP) into E. coli, and that the endogenous replication machinery uses them to accurately replicate a plasmid containing d5SICS-dNaM. Neither the presence of the unnatural triphosphates nor the replication of the UBP introduces a significant growth burden. Lastly, we find that the UBP is not efficiently excised by DNA repair pathways. Thus, the resulting bacterium is the first organism to stably propagate an expanded genetic alphabet.
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Affiliation(s)
- Denis A Malyshev
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Kirandeep Dhami
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Thomas Lavergne
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Tingjian Chen
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Nan Dai
- New England Biolabs, 240 County Road, Ipswich, Massachusetts 01938, USA
| | - Jeremy M Foster
- New England Biolabs, 240 County Road, Ipswich, Massachusetts 01938, USA
| | - Ivan R Corrêa
- New England Biolabs, 240 County Road, Ipswich, Massachusetts 01938, USA
| | - Floyd E Romesberg
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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16
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Hfq protein deficiency in Escherichia coli affects ColE1-like but not λ plasmid DNA replication. Plasmid 2014; 73:10-5. [PMID: 24811974 DOI: 10.1016/j.plasmid.2014.04.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 04/21/2014] [Accepted: 04/23/2014] [Indexed: 12/19/2022]
Abstract
Hfq is a nucleic acid-binding protein involved in controlling several aspects of RNA metabolism. It achieves this regulatory function by modulating the translational activity and stability of different mRNAs, generally via interactions with stress-related small regulatory sRNAs. However, besides its role in the coordination of translation of bacterial mRNA, Hfq is also a nucleoid-associated DNA-binding protein. Motivated by the above property of Hfq, we investigated if hfq gene mutation has implications for the regulation of DNA replication. Efficiency of ColE1-like (pMB1- and p15A replicons) and bacteriophage λ-derived plasmids' replication has been investigated in wild-type strain and otherwise isogenic hfq mutant of Escherichia coli. Significant differences in plasmid amount and kinetics of plasmid DNA synthesis were observed between the two tested bacterial hosts for ColE1-like replicons, but not for λ plasmid. Furthermore, ColE1-like plasmids replicated more efficiently in wild-type cells than in the hfq mutant in the early exponential phase of growth, but less efficiently in late exponential and early stationary phases. Hfq levels in the wild-type host, estimated by Western-blotting, were increased at the latter phases relative to the former one. Moreover, effects of the hfq mutation on ColE1-like plasmid replication were impaired in the absence of the rom gene, coding for a protein enhancing RNA I-RNA II interactions during the control of the replication initiation. These results are discussed in the light of a potential mechanism by which Hfq protein may influence replication of some, but not all, replicons in E. coli.
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17
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Alexander DL, Lilly J, Hernandez J, Romsdahl J, Troll CJ, Camps M. Random mutagenesis by error-prone pol plasmid replication in Escherichia coli. Methods Mol Biol 2014; 1179:31-44. [PMID: 25055769 DOI: 10.1007/978-1-4939-1053-3_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Directed evolution is an approach that mimics natural evolution in the laboratory with the goal of modifying existing enzymatic activities or of generating new ones. The identification of mutants with desired properties involves the generation of genetic diversity coupled with a functional selection or screen. Genetic diversity can be generated using PCR or using in vivo methods such as chemical mutagenesis or error-prone replication of the desired sequence in a mutator strain. In vivo mutagenesis methods facilitate iterative selection because they do not require cloning, but generally produce a low mutation density with mutations not restricted to specific genes or areas within a gene. For this reason, this approach is typically used to generate new biochemical properties when large numbers of mutants can be screened or selected. Here we describe protocols for an advanced in vivo mutagenesis method that is based on error-prone replication of a ColE1 plasmid bearing the gene of interest. Compared to other in vivo mutagenesis methods, this plasmid-targeted approach allows increased mutation loads and facilitates iterative selection approaches. We also describe the mutation spectrum for this mutagenesis methodology in detail, and, using cycle 3 GFP as a target for mutagenesis, we illustrate the phenotypic diversity that can be generated using our method. In sum, error-prone Pol I replication is a mutagenesis method that is ideally suited for the evolution of new biochemical activities when a functional selection is available.
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Affiliation(s)
- David L Alexander
- Department of Biomolecular Engineering SOE2, University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
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18
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Troll C, Yoder J, Alexander D, Hernández J, Loh Y, Camps M. The mutagenic footprint of low-fidelity Pol I ColE1 plasmid replication in E. coli reveals an extensive interplay between Pol I and Pol III. Curr Genet 2013; 60:123-34. [PMID: 24185821 DOI: 10.1007/s00294-013-0415-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/16/2013] [Accepted: 10/17/2013] [Indexed: 11/24/2022]
Abstract
ColE1 plasmid replication is unidirectional and requires two DNA polymerases: DNA polymerase I (Pol I) and DNA polymerase III (Pol III). Pol I initiates leading-strand synthesis by extending an RNA primer, allowing the Pol III holoenzyme to assemble and finish replication of both strands. The goal of the present work is to study the interplay between Pol I and Pol III during ColE1 plasmid replication, to gain new insights into Pol I function in vivo. Our approach consists of using mutations generated by a low-fidelity mutant of Pol I (LF-Pol I) during replication of a ColE1 plasmid as a footprint for Pol I replication. This approach allowed mapping areas of Pol I replication on the plasmid with high resolution. In addition, we were able to approximate the strandedness of Pol I mutations throughout the plasmid, allowing us to estimate the spectrum of the LF-Pol I in vivo. Our study produced the following three mechanistic insights: (1) we identified the likely location of the polymerase switch at ~200 bp downstream of replication initiation; (2) we found evidence suggesting that Pol I can replicate both strands, supporting earlier studies indicating a functional redundancy between Pol I and Pol III (3) we found evidence pointing to a specific role of Pol I during termination of lagging-strand replication. In addition, we illustrate how our strand-specific footprinting approach can be used to dissect factors modulating Pol I fidelity in vivo.
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Affiliation(s)
- Christopher Troll
- Department of Microbiology and Environmental Toxicology, University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
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19
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Reyes-Lamothe R, Tran T, Meas D, Lee L, Li AM, Sherratt DJ, Tolmasky ME. High-copy bacterial plasmids diffuse in the nucleoid-free space, replicate stochastically and are randomly partitioned at cell division. Nucleic Acids Res 2013; 42:1042-51. [PMID: 24137005 PMCID: PMC3902917 DOI: 10.1093/nar/gkt918] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Bacterial plasmids play important roles in the metabolism, pathogenesis and bacterial evolution and are highly versatile biotechnological tools. Stable inheritance of plasmids depends on their autonomous replication and efficient partition to daughter cells at cell division. Active partition systems have not been identified for high-copy number plasmids, and it has been generally believed that they are partitioned randomly at cell division. Nevertheless, direct evidence for the cellular location of replicating and nonreplicating plasmids, and the partition mechanism has been lacking. We used as model pJHCMW1, a plasmid isolated from Klebsiella pneumoniae that includes two β-lactamase and two aminoglycoside resistance genes. Here we report that individual ColE1-type plasmid molecules are mobile and tend to be excluded from the nucleoid, mainly localizing at the cell poles but occasionally moving between poles along the long axis of the cell. As a consequence, at the moment of cell division, most plasmid molecules are located at the poles, resulting in efficient random partition to the daughter cells. Complete replication of individual molecules occurred stochastically and independently in the nucleoid-free space throughout the cell cycle, with a constant probability of initiation per plasmid.
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Affiliation(s)
- Rodrigo Reyes-Lamothe
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK, Department of Biology, McGill University, Montreal, Quebec H3G 0B1, Canada and Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, CA 92834-6850, USA
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20
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Hayes S, Erker C, Horbay MA, Marciniuk K, Wang W, Hayes C. Phage Lambda P protein: trans-activation, inhibition phenotypes and their suppression. Viruses 2013; 5:619-53. [PMID: 23389467 PMCID: PMC3640518 DOI: 10.3390/v5020619] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 01/21/2013] [Accepted: 01/29/2013] [Indexed: 11/16/2022] Open
Abstract
The initiation of bacteriophage λ replication depends upon interactions between the oriλ DNA site, phage proteins O and P, and E. coli host replication proteins. P exhibits a high affinity for DnaB, the major replicative helicase for unwinding double stranded DNA. The concept of P-lethality relates to the hypothesis that P can sequester DnaB and in turn prevent cellular replication initiation from oriC. Alternatively, it was suggested that P-lethality does not involve an interaction between P and DnaB, but is targeted to DnaA. P-lethality is assessed by examining host cells for transformation by ColE1-type plasmids that can express P, and the absence of transformants is attributed to a lethal effect of P expression. The plasmid we employed enabled conditional expression of P, where under permissive conditions, cells were efficiently transformed. We observed that ColE1 replication and plasmid establishment upon transformation is extremely sensitive to P, and distinguish this effect from P-lethality directed to cells. We show that alleles of dnaB protect the variant cells from P expression. P-dependent cellular filamentation arose in ΔrecA or lexA[Ind-] cells, defective for SOS induction. Replication propagation and restart could represent additional targets for P interference of E. coli replication, beyond the oriC-dependent initiation step.
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Affiliation(s)
- Sidney Hayes
- Department of Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, S7N 5E5, Canada.
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21
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Million-Weaver S, Alexander DL, Allen JM, Camps M. Quantifying plasmid copy number to investigate plasmid dosage effects associated with directed protein evolution. Methods Mol Biol 2012; 834:33-48. [PMID: 22144351 PMCID: PMC3804865 DOI: 10.1007/978-1-61779-483-4_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Our laboratory specializes in directed protein evolution, i.e., evolution of proteins under defined selective pressures in the laboratory. Our target genes are encoded in ColE1 plasmids to facilitate the generation of libraries in vivo. We have observed that when random mutations are not restricted to the coding sequence of the target genes, directed evolution results in a strong positive selection of plasmid origin of replication (ori) mutations. Surprisingly, this is true even during evolution of new biochemical activities, when the activity that is being selected was not originally present. The selected plasmid ori mutations are diverse and produce a range of plasmid copy numbers, suggesting a complex interplay between ori and coding mutations rather than a simple enhancement of level of expression of the target gene. Thus, plasmid dosage may contribute significantly to evolution by fine-tuning levels of activity. Here, we present examples illustrating these observations as well as our methods for efficient quantification of plasmid copy number.
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Affiliation(s)
- Samuel Million-Weaver
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, CA, USA
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