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Yang Y, Zou Y, Chen X, Sun H, Hua X, Johnston L, Zeng X, Qiao S, Ye C. Metabolic engineering of Escherichia coli for the production of 5-aminolevulinic acid based on combined metabolic pathway modification and reporter-guided mutant selection (RGMS). BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:82. [PMID: 38886801 PMCID: PMC11184883 DOI: 10.1186/s13068-024-02530-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 06/10/2024] [Indexed: 06/20/2024]
Abstract
BACKGROUND 5-Aminolevulinic acid (ALA) recently received much attention due to its potential application in many fields such as medicine, nutrition and agriculture. Metabolic engineering is an efficient strategy to improve microbial production of 5-ALA. RESULTS In this study, an ALA production strain of Escherichia coli was constructed by rational metabolic engineering and stepwise improvement. A metabolic strategy to produce ALA directly from glucose in this recombinant E. coli via both C4 and C5 pathways was applied herein. The expression of a modified hemARS gene and rational metabolic engineering by gene knockouts significantly improved ALA production from 765.9 to 2056.1 mg/L. Next, we tried to improve ALA production by RGMS-directed evolution of eamA gene. After RGMS, the ALA yield of strain A2-ASK reached 2471.3 mg/L in flask. Then, we aimed to improve the oxidation resistance of cells by overexpressing sodB and katE genes and ALA yield reached 2703.8 mg/L. A final attempt is to replace original promoter of hemB gene in genome with a weaker one to decrease its expression. After 24 h cultivation, a high ALA yield of 19.02 g/L was achieved by 108-ASK in a 5 L fermenter. CONCLUSIONS These results suggested that an industrially competitive strain can be efficiently developed by metabolic engineering based on combined rational modification and optimization of gene expression.
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Affiliation(s)
- Yuting Yang
- State Key Laboratory of Animal Nutrition and Feeding, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing, 100193, China
- Beijing Key Laboratory of Bio-Feed Additives, Beijing, 100193, China
| | - Yuhong Zou
- State Key Laboratory of Animal Nutrition and Feeding, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing, 100193, China
- Beijing Key Laboratory of Bio-Feed Additives, Beijing, 100193, China
| | - Xi Chen
- State Key Laboratory for Agro-Biotechnology, Ministry of Agriculture and Rural Affairs, Key Laboratory for Pest Monitoring and Green Management, Department of Plant Pathology, China Agricultural University, Beijing, 100193, China
| | - Haidong Sun
- National Feed Engineering Technology Research Centre, Beijing, 100193, China
| | - Xia Hua
- State Key Laboratory for Agro-Biotechnology, Ministry of Agriculture and Rural Affairs, Key Laboratory for Pest Monitoring and Green Management, Department of Plant Pathology, China Agricultural University, Beijing, 100193, China
| | - Lee Johnston
- Swine Nutrition and Production, West Central Research and Outreach Center, University of Minnesota, Morris, MN, 56267, USA
| | - Xiangfang Zeng
- State Key Laboratory of Animal Nutrition and Feeding, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing, 100193, China
- Beijing Key Laboratory of Bio-Feed Additives, Beijing, 100193, China
| | - Shiyan Qiao
- State Key Laboratory of Animal Nutrition and Feeding, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing, 100193, China
- Beijing Key Laboratory of Bio-Feed Additives, Beijing, 100193, China
| | - Changchuan Ye
- State Key Laboratory of Animal Nutrition and Feeding, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing, 100193, China.
- Department of Animal Science, College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
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2
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Royzenblat SK, Freddolino L. Spatio-temporal organization of the E. coli chromosome from base to cellular length scales. EcoSal Plus 2024:eesp00012022. [PMID: 38864557 DOI: 10.1128/ecosalplus.esp-0001-2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 04/17/2024] [Indexed: 06/13/2024]
Abstract
Escherichia coli has been a vital model organism for studying chromosomal structure, thanks, in part, to its small and circular genome (4.6 million base pairs) and well-characterized biochemical pathways. Over the last several decades, we have made considerable progress in understanding the intricacies of the structure and subsequent function of the E. coli nucleoid. At the smallest scale, DNA, with no physical constraints, takes on a shape reminiscent of a randomly twisted cable, forming mostly random coils but partly affected by its stiffness. This ball-of-spaghetti-like shape forms a structure several times too large to fit into the cell. Once the physiological constraints of the cell are added, the DNA takes on overtwisted (negatively supercoiled) structures, which are shaped by an intricate interplay of many proteins carrying out essential biological processes. At shorter length scales (up to about 1 kb), nucleoid-associated proteins organize and condense the chromosome by inducing loops, bends, and forming bridges. Zooming out further and including cellular processes, topological domains are formed, which are flanked by supercoiling barriers. At the megabase-scale both large, highly self-interacting regions (macrodomains) and strong contacts between distant but co-regulated genes have been observed. At the largest scale, the nucleoid forms a helical ellipsoid. In this review, we will explore the history and recent advances that pave the way for a better understanding of E. coli chromosome organization and structure, discussing the cellular processes that drive changes in DNA shape, and what contributes to compaction and formation of dynamic structures, and in turn how bacterial chromatin affects key processes such as transcription and replication.
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Affiliation(s)
- Sonya K Royzenblat
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Lydia Freddolino
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Computational Medicine & Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA
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3
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Çöl B, Kürkçü MS, Di Bek E. Genome-Wide Screens Identify Genes Responsible for Intrinsic Boric Acid Resistance in Escherichia coli. Biol Trace Elem Res 2024:10.1007/s12011-024-04129-0. [PMID: 38466471 DOI: 10.1007/s12011-024-04129-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 02/24/2024] [Indexed: 03/13/2024]
Abstract
Boric acid (BA) has antimicrobial properties and is used to combat bacterial infections, including Enterobacteria. However, the molecular mechanisms and cellular responses to BA are still unknown. This genomics study aims to provide new information on the genes and molecular mechanisms related to the antimicrobial effect of BA in Escherichia coli. The Keio collection of E. coli was used to screen 3985 single-gene knockout strains in order to identify mutant strains that were sensitive or hypersensitive to BA at certain concentrations. The mutant strains were exposed to different concentrations of BA ranging from 0 to 120 mM in LB media. Through genome-wide screens, 92 mutants were identified that were relatively sensitive to BA at least at one concentration tested. The related biological processes in the particular cellular system were listed. This study demonstrates that intrinsic BA resistance is the result of various mechanisms acting together. Additionally, we identified eighteen out of ninety-two mutant strains (Delta_aceF, aroK, cheZ, dinJ, galS, garP, glxK, nohA, talB, torR, trmU, trpR, yddE, yfeS, ygaV, ylaC, yoaC, yohN) that exhibited sensitivity using other methods. To increase sensitivity to BA, we constructed double and triple knockout mutants of the selected sensitive mutants. In certain instances, engineered double and triple mutants exhibited significantly amplified effects. Overall, our analysis of these findings offers further understanding of the mechanisms behind BA toxicity and intrinsic resistance in E. coli.
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Affiliation(s)
- Bekir Çöl
- Faculty of Science, Department of Biology, Mugla Sitki Kocman University, Mugla, Turkey.
- Research Laboratories Center, Biotechnology Research Center, Mugla Sitki Kocman University, Mugla, Turkey.
| | - Merve Sezer Kürkçü
- Research Laboratories Center, Biotechnology Research Center, Mugla Sitki Kocman University, Mugla, Turkey
- Research and Application Center For Research Laboratories, Mugla Sitki Kocman University, Mugla, Turkey
| | - Esra Di Bek
- Research Laboratories Center, Biotechnology Research Center, Mugla Sitki Kocman University, Mugla, Turkey
- Köyceğiz Vocational School of Health Services, Department of Pharmacy Services, Mugla Sitki Kocman University, Mugla, Turkey
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4
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Doranga S, Krogfelt KA, Cohen PS, Conway T. Nutrition of Escherichia coli within the intestinal microbiome. EcoSal Plus 2024:eesp00062023. [PMID: 38417452 DOI: 10.1128/ecosalplus.esp-0006-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 11/03/2023] [Indexed: 03/01/2024]
Abstract
In this chapter, we update our 2004 review of "The Life of Commensal Escherichia coli in the Mammalian Intestine" (https://doi.org/10.1128/ecosalplus.8.3.1.2), with a change of title that reflects the current focus on "Nutrition of E. coli within the Intestinal Microbiome." The earlier part of the previous two decades saw incremental improvements in understanding the carbon and energy sources that E. coli and Salmonella use to support intestinal colonization. Along with these investigations of electron donors came a better understanding of the electron acceptors that support the respiration of these facultative anaerobes in the gastrointestinal tract. Hundreds of recent papers add to what was known about the nutrition of commensal and pathogenic enteric bacteria. The fact that each biotype or pathotype grows on a different subset of the available nutrients suggested a mechanism for succession of commensal colonizers and invasion by enteric pathogens. Competition for nutrients in the intestine has also come to be recognized as one basis for colonization resistance, in which colonized strain(s) prevent colonization by a challenger. In the past decade, detailed investigations of fiber- and mucin-degrading anaerobes added greatly to our understanding of how complex polysaccharides support the hundreds of intestinal microbiome species. It is now clear that facultative anaerobes, which usually cannot degrade complex polysaccharides, live in symbiosis with the anaerobic degraders. This concept led to the "restaurant hypothesis," which emphasizes that facultative bacteria, such as E. coli, colonize the intestine as members of mixed biofilms and obtain the sugars they need for growth locally through cross-feeding from polysaccharide-degrading anaerobes. Each restaurant represents an intestinal niche. Competition for those niches determines whether or not invaders are able to overcome colonization resistance and become established. Topics centered on the nutritional basis of intestinal colonization and gastrointestinal health are explored here in detail.
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Affiliation(s)
- Sudhir Doranga
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Karen A Krogfelt
- Department of Science and Environment, Pandemix Center Roskilde University, Roskilde, Denmark
| | - Paul S Cohen
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
| | - Tyrrell Conway
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, USA
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5
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Campbell RP, Whittington AC, Zorio DAR, Miller BG. Recruitment of a Middling Promiscuous Enzyme Drives Adaptive Metabolic Evolution in Escherichia coli. Mol Biol Evol 2023; 40:msad202. [PMID: 37708398 PMCID: PMC10519446 DOI: 10.1093/molbev/msad202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 08/29/2023] [Accepted: 09/05/2023] [Indexed: 09/16/2023] Open
Abstract
A key step in metabolic pathway evolution is the recruitment of promiscuous enzymes to perform new functions. Despite the recognition that promiscuity is widespread in biology, factors dictating the preferential recruitment of one promiscuous enzyme over other candidates are unknown. Escherichia coli contains four sugar kinases that are candidates for recruitment when the native glucokinase machinery is deleted-allokinase (AlsK), manno(fructo)kinase (Mak), N-acetylmannosamine kinase (NanK), and N-acetylglucosamine kinase (NagK). The catalytic efficiencies of these enzymes are 103- to 105-fold lower than native glucokinases, ranging from 2,400 M-1 s-1 for the most active candidate, NagK, to 15 M-1 s-1 for the least active candidate, AlsK. To investigate the relationship between catalytic activities of promiscuous enzymes and their recruitment, we performed adaptive evolution of a glucokinase-deficient E. coli strain to restore glycolytic metabolism. We observed preferential recruitment of NanK via a trajectory involving early mutations that facilitate glucose uptake and amplify nanK transcription, followed by nonsynonymous substitutions in NanK that enhance the enzyme's promiscuous glucokinase activity. These substitutions reduced the native activity of NanK and reduced organismal fitness during growth on an N-acetylated carbon source, indicating that enzyme recruitment comes at a cost for growth on other substrates. Notably, the two most active candidates, NagK and Mak, were not recruited, suggesting that catalytic activity alone does not dictate evolutionary outcomes. The results highlight our lack of knowledge regarding biological drivers of enzyme recruitment and emphasize the need for a systems-wide approach to identify factors facilitating or constraining this important adaptive process.
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Affiliation(s)
- Ryan P Campbell
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
| | - A Carl Whittington
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Diego A R Zorio
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Brian G Miller
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
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6
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Chen Y, Lin YCD, Luo Y, Cai X, Qiu P, Cui S, Wang Z, Huang HY, Huang HD. Quantitative model for genome-wide cyclic AMP receptor protein binding site identification and characteristic analysis. Brief Bioinform 2023; 24:7145906. [PMID: 37114659 DOI: 10.1093/bib/bbad138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 03/10/2023] [Accepted: 03/16/2023] [Indexed: 04/29/2023] Open
Abstract
Cyclic AMP receptor proteins (CRPs) are important transcription regulators in many species. The prediction of CRP-binding sites was mainly based on position-weighted matrixes (PWMs). Traditional prediction methods only considered known binding motifs, and their ability to discover inflexible binding patterns was limited. Thus, a novel CRP-binding site prediction model called CRPBSFinder was developed in this research, which combined the hidden Markov model, knowledge-based PWMs and structure-based binding affinity matrixes. We trained this model using validated CRP-binding data from Escherichia coli and evaluated it with computational and experimental methods. The result shows that the model not only can provide higher prediction performance than a classic method but also quantitatively indicates the binding affinity of transcription factor binding sites by prediction scores. The prediction result included not only the most knowns regulated genes but also 1089 novel CRP-regulated genes. The major regulatory roles of CRPs were divided into four classes: carbohydrate metabolism, organic acid metabolism, nitrogen compound metabolism and cellular transport. Several novel functions were also discovered, including heterocycle metabolic and response to stimulus. Based on the functional similarity of homologous CRPs, we applied the model to 35 other species. The prediction tool and the prediction results are online and are available at: https://awi.cuhk.edu.cn/∼CRPBSFinder.
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Affiliation(s)
- Yigang Chen
- School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
- Warshel Institute for Computational Biology, School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
| | - Yang-Chi-Dung Lin
- School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
- Warshel Institute for Computational Biology, School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
| | - Yijun Luo
- School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
| | - Xiaoxuan Cai
- School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
- Warshel Institute for Computational Biology, School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
| | - Peng Qiu
- School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
| | - Shidong Cui
- School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
- Warshel Institute for Computational Biology, School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
| | - Zhe Wang
- School of Humanities and Social Science, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
| | - Hsi-Yuan Huang
- School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
- Warshel Institute for Computational Biology, School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
| | - Hsien-Da Huang
- School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
- Warshel Institute for Computational Biology, School of Medicine, Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Longgang District, Shenzhen, Guangdong Province 518172, China
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7
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Sadler J, Brewster RC, Kjeldsen A, González AF, Nirkko JS, Varzandeh S, Wallace S. Overproduction of Native and Click-able Colanic Acid Slime from Engineered Escherichia coli. JACS AU 2023; 3:378-383. [PMID: 36873680 PMCID: PMC9976346 DOI: 10.1021/jacsau.2c00583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/27/2023] [Accepted: 01/27/2023] [Indexed: 06/18/2023]
Abstract
The fundamental biology and application of bacterial exopolysaccharides is gaining increasing attention. However, current synthetic biology efforts to produce the major component of Escherichia sp. slime, colanic acid, and functional derivatives thereof have been limited. Herein, we report the overproduction of colanic acid (up to 1.32 g/L) from d-glucose in an engineered strain of Escherichia coli JM109. Furthermore, we report that chemically synthesized l-fucose analogues containing an azide motif can be metabolically incorporated into the slime layer via a heterologous fucose salvage pathway from Bacteroides sp. and used in a click reaction to attach an organic cargo to the cell surface. This molecular-engineered biopolymer has potential as a new tool for use in chemical, biological, and materials research.
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Affiliation(s)
| | | | | | | | | | | | - Stephen Wallace
- Institute
of Quantitative Biology,
Biochemistry and Biotechnology, School of Biological Sciences, Roger
Land Building, Alexander Crum Brown Road, The King’s Buildings,
Edinburgh, EH9 3FF.
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8
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Kim YE, Cho KH, Bang I, Kim CH, Ryu YS, Kim Y, Choi EM, Nong LK, Kim D, Lee SK. Characterization of an Entner-Doudoroff pathway-activated Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:120. [PMID: 36352474 PMCID: PMC9648032 DOI: 10.1186/s13068-022-02219-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Escherichia coli have both the Embden-Meyerhof-Parnas pathway (EMPP) and Entner-Doudoroff pathway (EDP) for glucose breakdown, while the EDP primarily remains inactive for glucose metabolism. However, EDP is a more favorable route than EMPP for the production of certain products. RESULTS EDP was activated by deleting the pfkAB genes in conjunction with subsequent adaptive laboratory evolution (ALE). The evolved strains acquired mutations in transcriptional regulatory genes for glycolytic process (crp, galR, and gntR) and in glycolysis-related genes (gnd, ptsG, and talB). The genotypic, transcriptomic and phenotypic analyses of those mutations deepen our understanding of their beneficial effects on cellulosic biomass bio-conversion. On top of these scientific understandings, we further engineered the strain to produce higher level of lycopene and 3-hydroxypropionic acid. CONCLUSIONS These results indicate that the E. coli strain has innate capability to use EDP in lieu of EMPP for glucose metabolism, and this versatility can be harnessed to further engineer E. coli for specific biotechnological applications.
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Affiliation(s)
- Ye Eun Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Kyung Hyun Cho
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Ina Bang
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Chang Hee Kim
- Department of Biomedical Engineering, UNIST, Ulsan, 44919, Republic of Korea
| | - Young Shin Ryu
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Yuchan Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Eun Mi Choi
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Linh Khanh Nong
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Donghyuk Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
- Department of Biomedical Engineering, UNIST, Ulsan, 44919, Republic of Korea.
| | - Sung Kuk Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
- Department of Biomedical Engineering, UNIST, Ulsan, 44919, Republic of Korea.
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9
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Jones RA, Yee WX, Mader K, Tang CM, Cehovin A. Markerless gene editing in Neisseria gonorrhoeae. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35763318 DOI: 10.1099/mic.0.001201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Neisseria gonorrhoeae, the gonococcus, is a pathogen of major public health concern, but sophisticated approaches to gene manipulation are limited for this species. For example, there are few methods for generating markerless mutations, which allow the generation of precise point mutations and deletions without introducing additional DNA sequence. Markerless mutations are central to studying pathogenesis, the spread of antimicrobial resistance (AMR) and for vaccine development. Here we describe the use of galK as a counter-selectable marker that can be used for markerless mutagenesis in N. gonorrhoeae. galK encodes galactokinase, an enzyme that metabolizes galactose in bacteria that can utilize it as a sole carbon source. GalK can also phosphorylate a galactose analogue, 2-deoxy-galactose (2-DOG), into a toxic, non-metabolisable intermediate, 2-deoxy-galactose-1-phosphate. We utilized this property of GalK to develop a markerless approach for mutagenesis in N. gonorrhoeae. We successfully deleted both chromosomally and plasmid-encoded genes, that are important for gonococcal vaccine development and studies of AMR spread. We designed a positive-negative selection cassette, based on an antibiotic resistance marker and galK, that efficiently rendered N. gonorrhoeae susceptible to growth on 2-DOG. We then adapted the galK-based counter-selection and the use of 2-DOG for markerless mutagenesis, and applied biochemical and phenotypic analyses to confirm the absence of target genes. We show that our markerless mutagenesis method for N. gonorrhoeae has a high success rate, and should be a valuable gene editing tool in the future.
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Affiliation(s)
- Rebekah A Jones
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, UK
| | - Wearn Xin Yee
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, UK
| | - Kahlio Mader
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, UK
| | - Christoph M Tang
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, UK
| | - Ana Cehovin
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, UK
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10
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Computing within bacteria: Programming of bacterial behavior by means of a plasmid encoding a perceptron neural network. Biosystems 2022; 213:104608. [DOI: 10.1016/j.biosystems.2022.104608] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/07/2021] [Accepted: 01/11/2022] [Indexed: 01/12/2023]
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11
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Keizers M, Dobrindt U, Berger M. A Simple Biosensor-Based Assay for Quantitative Autoinducer-2 Analysis. ACS Synth Biol 2022; 11:747-759. [PMID: 35090122 DOI: 10.1021/acssynbio.1c00459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bacteria produce and react to interspecies signaling molecules in order to control the expression of genes that are particularly beneficial when they are expressed by a bacterial community. In addition to intraspecies communication, the signaling molecule autoinducer-2 (AI-2) can also serve for interspecies communication between Gram-positive and Gram-negative bacteria and is therefore of particular interest. The analysis and quantification of AI-2 are essential for understanding population density-dependent changes in bacterial behavior and pathogenicity. However, currently available bioassays for AI-2 quantification are rather complex, have narrow detection ranges, and are very sensitive to trace components of, for example, growth media. To facilitate and improve the detection of AI-2, we have developed an Escherichia coli biosensor-based assay that is sensitive, cheap, fast, robust, and reliable in the quantification of biologically active AI-2. The bioassay is based on an lsr promoter-fluorescent reporter gene fusion cassette that we chromosomally integrated in a biosensor strain, but the cassette can also be used in a low-copy number plasmid for the application in other Gram-negative bacterial species. We show here that AI-2 quantification was possible in a concentration range from 400 nM to 100 μM and that a critical interpretation of the kinetics of the measurements can reveal sugar interference. With the help of our biosensor strain, coculture experiments were done to test the capability and kinetics of AI-2 secretion by various Gram-negative bacteria in real time. Finally, calibration curves were used to calculate the absolute AI-2 concentration in cell-free bacterial samples.
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Affiliation(s)
- Marla Keizers
- Institute of Hygiene, University of Münster, Münster 48149, Germany
| | - Ulrich Dobrindt
- Institute of Hygiene, University of Münster, Münster 48149, Germany
| | - Michael Berger
- Institute of Hygiene, University of Münster, Münster 48149, Germany
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12
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Jeon HJ, Lee Y, N MPA, Wang X, Chattoraj DK, Lim HM. sRNA-mediated regulation of gal mRNA in E. coli: Involvement of transcript cleavage by RNase E together with Rho-dependent transcription termination. PLoS Genet 2021; 17:e1009878. [PMID: 34710092 PMCID: PMC8577784 DOI: 10.1371/journal.pgen.1009878] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 11/09/2021] [Accepted: 10/14/2021] [Indexed: 11/18/2022] Open
Abstract
In bacteria, small non-coding RNAs (sRNAs) bind to target mRNAs and regulate their translation and/or stability. In the polycistronic galETKM operon of Escherichia coli, binding of the Spot 42 sRNA to the operon transcript leads to the generation of galET mRNA. The mechanism of this regulation has remained unclear. We show that sRNA-mRNA base pairing at the beginning of the galK gene leads to both transcription termination and transcript cleavage within galK, and generates galET mRNAs with two different 3'-OH ends. Transcription termination requires Rho, and transcript cleavage requires the endonuclease RNase E. The sRNA-mRNA base-paired segments required for generating the two galET species are different, indicating different sequence requirements for the two events. The use of two targets in an mRNA, each of which causes a different outcome, appears to be a novel mode of action for a sRNA. Considering the prevalence of potential sRNA targets at cistron junctions, the generation of new mRNA species by the mechanisms reported here might be a widespread mode of bacterial gene regulation.
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Affiliation(s)
- Heung Jin Jeon
- Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
- Infection Control Convergence Research Center, College of Medicine, Chungnam National University, Daejeon, Republic of Korea
| | - Yonho Lee
- Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
| | - Monford Paul Abishek N
- Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
| | - Xun Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, PR China
| | - Dhruba K. Chattoraj
- Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Heon M. Lim
- Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
- * E-mail:
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13
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Gwon DA, Seok JY, Jung GY, Lee JW. Biosensor-Assisted Adaptive Laboratory Evolution for Violacein Production. Int J Mol Sci 2021; 22:ijms22126594. [PMID: 34205463 PMCID: PMC8233975 DOI: 10.3390/ijms22126594] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/16/2021] [Accepted: 06/17/2021] [Indexed: 11/16/2022] Open
Abstract
Violacein is a naturally occurring purple pigment, widely used in cosmetics and has potent antibacterial and antiviral properties. Violacein can be produced from tryptophan, consequently sufficient tryptophan biosynthesis is the key to violacein production. However, the complicated biosynthetic pathways and regulatory mechanisms often make the tryptophan overproduction challenging in Escherichia coli. In this study, we used the adaptive laboratory evolution (ALE) strategy to improve violacein production using galactose as a carbon source. During the ALE, a tryptophan-responsive biosensor was employed to provide selection pressure to enrich tryptophan-producing cells. From the biosensor-assisted ALE, we obtained an evolved population of cells capable of effectively catabolizing galactose to tryptophan and subsequently used the population to obtain the best violacein producer. In addition, whole-genome sequencing of the evolved strain identified point mutations beneficial to the overproduction. Overall, we demonstrated that the biosensor-assisted ALE strategy could be used to rapidly and selectively evolve the producers to yield high violacein production.
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Affiliation(s)
- Da-ae Gwon
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea; (D.G.); (G.Y.J.)
| | - Joo Yeon Seok
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea;
| | - Gyoo Yeol Jung
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea; (D.G.); (G.Y.J.)
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea;
| | - Jeong Wook Lee
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea; (D.G.); (G.Y.J.)
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea;
- Correspondence:
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14
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Kinnersley M, Schwartz K, Yang DD, Sherlock G, Rosenzweig F. Evolutionary dynamics and structural consequences of de novo beneficial mutations and mutant lineages arising in a constant environment. BMC Biol 2021; 19:20. [PMID: 33541358 PMCID: PMC7863352 DOI: 10.1186/s12915-021-00954-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 01/08/2021] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Microbial evolution experiments can be used to study the tempo and dynamics of evolutionary change in asexual populations, founded from single clones and growing into large populations with multiple clonal lineages. High-throughput sequencing can be used to catalog de novo mutations as potential targets of selection, determine in which lineages they arise, and track the fates of those lineages. Here, we describe a long-term experimental evolution study to identify targets of selection and to determine when, where, and how often those targets are hit. RESULTS We experimentally evolved replicate Escherichia coli populations that originated from a mutator/nonsense suppressor ancestor under glucose limitation for between 300 and 500 generations. Whole-genome, whole-population sequencing enabled us to catalog 3346 de novo mutations that reached > 1% frequency. We sequenced the genomes of 96 clones from each population when allelic diversity was greatest in order to establish whether mutations were in the same or different lineages and to depict lineage dynamics. Operon-specific mutations that enhance glucose uptake were the first to rise to high frequency, followed by global regulatory mutations. Mutations related to energy conservation, membrane biogenesis, and mitigating the impact of nonsense mutations, both ancestral and derived, arose later. New alleles were confined to relatively few loci, with many instances of identical mutations arising independently in multiple lineages, among and within replicate populations. However, most never exceeded 10% in frequency and were at a lower frequency at the end of the experiment than at their maxima, indicating clonal interference. Many alleles mapped to key structures within the proteins that they mutated, providing insight into their functional consequences. CONCLUSIONS Overall, we find that when mutational input is increased by an ancestral defect in DNA repair, the spectrum of high-frequency beneficial mutations in a simple, constant resource-limited environment is narrow, resulting in extreme parallelism where many adaptive mutations arise but few ever go to fixation.
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Affiliation(s)
- Margie Kinnersley
- Division of Biological Sciences, The University of Montana, Missoula, MT, 59812, USA
| | - Katja Schwartz
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305-5120, USA
| | - Dong-Dong Yang
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Gavin Sherlock
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305-5120, USA.
| | - Frank Rosenzweig
- Division of Biological Sciences, The University of Montana, Missoula, MT, 59812, USA.
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
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15
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Morrison M, Razo-Mejia M, Phillips R. Reconciling kinetic and thermodynamic models of bacterial transcription. PLoS Comput Biol 2021; 17:e1008572. [PMID: 33465069 PMCID: PMC7845990 DOI: 10.1371/journal.pcbi.1008572] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 01/29/2021] [Accepted: 11/28/2020] [Indexed: 11/18/2022] Open
Abstract
The study of transcription remains one of the centerpieces of modern biology with implications in settings from development to metabolism to evolution to disease. Precision measurements using a host of different techniques including fluorescence and sequencing readouts have raised the bar for what it means to quantitatively understand transcriptional regulation. In particular our understanding of the simplest genetic circuit is sufficiently refined both experimentally and theoretically that it has become possible to carefully discriminate between different conceptual pictures of how this regulatory system works. This regulatory motif, originally posited by Jacob and Monod in the 1960s, consists of a single transcriptional repressor binding to a promoter site and inhibiting transcription. In this paper, we show how seven distinct models of this so-called simple-repression motif, based both on thermodynamic and kinetic thinking, can be used to derive the predicted levels of gene expression and shed light on the often surprising past success of the thermodynamic models. These different models are then invoked to confront a variety of different data on mean, variance and full gene expression distributions, illustrating the extent to which such models can and cannot be distinguished, and suggesting a two-state model with a distribution of burst sizes as the most potent of the seven for describing the simple-repression motif.
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Affiliation(s)
- Muir Morrison
- Department of Physics, California Institute of Technology, Pasadena, California, USA
| | - Manuel Razo-Mejia
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Rob Phillips
- Department of Physics, California Institute of Technology, Pasadena, California, USA
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
- * E-mail:
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16
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Molecular Mechanism of LEDGF/p75 Dimerization. Structure 2020; 28:1288-1299.e7. [DOI: 10.1016/j.str.2020.08.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 07/19/2020] [Accepted: 08/28/2020] [Indexed: 12/19/2022]
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17
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Banerjee D, Eng T, Lau AK, Sasaki Y, Wang B, Chen Y, Prahl JP, Singan VR, Herbert RA, Liu Y, Tanjore D, Petzold CJ, Keasling JD, Mukhopadhyay A. Genome-scale metabolic rewiring improves titers rates and yields of the non-native product indigoidine at scale. Nat Commun 2020; 11:5385. [PMID: 33097726 PMCID: PMC7584609 DOI: 10.1038/s41467-020-19171-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/30/2020] [Indexed: 01/06/2023] Open
Abstract
High titer, rate, yield (TRY), and scalability are challenging metrics to achieve due to trade-offs between carbon use for growth and production. To achieve these metrics, we take the minimal cut set (MCS) approach that predicts metabolic reactions for elimination to couple metabolite production strongly with growth. We compute MCS solution-sets for a non-native product indigoidine, a sustainable pigment, in Pseudomonas putida KT2440, an emerging industrial microbe. From the 63 solution-sets, our omics guided process identifies one experimentally feasible solution requiring 14 simultaneous reaction interventions. We implement a total of 14 genes knockdowns using multiplex-CRISPRi. MCS-based solution shifts production from stationary to exponential phase. We achieve 25.6 g/L, 0.22 g/l/h, and ~50% maximum theoretical yield (0.33 g indigoidine/g glucose). These phenotypes are maintained from batch to fed-batch mode, and across scales (100-ml shake flasks, 250-ml ambr®, and 2-L bioreactors).
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Affiliation(s)
- Deepanwita Banerjee
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Thomas Eng
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Andrew K Lau
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yusuke Sasaki
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Brenda Wang
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yan Chen
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jan-Philip Prahl
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Advanced Biofuel and Bioproduct Process Development Unit, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
| | - Vasanth R Singan
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Robin A Herbert
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yuzhong Liu
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Deepti Tanjore
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Advanced Biofuel and Bioproduct Process Development Unit, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
| | - Christopher J Petzold
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jay D Keasling
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- QB3 Institute, University of California-Berkeley, 5885 Hollis Street, 4th Floor, Emeryville, CA, 94608, USA
- Department of Chemical & Biomolecular Engineering, University of California, Berkeley, CA, 94720, USA
- Department of Bioengineering, University of California, Berkeley, CA, 94720, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University Denmark, 2970, Horsholm, Denmark
- Synthetic Biochemistry Center, Institute for Synthetic Biology, Shenzhen Institutes for Advanced Technologies, Shenzhen, China
| | - Aindrila Mukhopadhyay
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA.
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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18
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Evolution of an Escherichia coli PTS - strain: a study of reproducibility and dynamics of an adaptive evolutive process. Appl Microbiol Biotechnol 2020; 104:9309-9325. [PMID: 32954454 DOI: 10.1007/s00253-020-10885-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 08/12/2020] [Accepted: 09/04/2020] [Indexed: 10/23/2022]
Abstract
Adaptive laboratory evolution (ALE) has been used to study and solve pressing questions about evolution, especially for the study of the development of mutations that confer increased fitness during evolutionary processes. In this contribution, we investigated how the evolutionary process conducted with the PTS- mutant of Escherichia coli PB11 in three parallel batch cultures allowed the restoration of rapid growth with glucose as the carbon source. The significant findings showed that genomic sequence analysis of a set of newly evolved mutants isolated from ALE experiments 2-3 developed some essential mutations, which efficiently improved the fast-growing phenotypes throughout different fitness landscapes. Regulator galR was the target of several mutations such as SNPs, partial and total deletions, and insertion of an IS1 element and thus indicated the relevance of a null mutation of this gene in the adaptation of the evolving population of PB11 during the parallel ALE experiments. These mutations resulted in the selection of MglB and GalP as the primary glucose transporters by the evolving population, but further selection of at least a second adaptive mutation was also necessary. We found that mutations in the yfeO, rppH, and rng genes improved the fitness advantage of evolving PTS- mutants and resulted in amplification of leaky activity in Glk for glucose phosphorylation and upregulation of glycolytic and other growth-related genes. Notably, we determined that these mutations appeared and were fixed in the evolving populations between 48 and 72 h of cultivation, which resulted in the selection of fast-growing mutants during one ALE experiments in batch cultures of 80 h duration.Key points• ALE experiments selected evolved mutants through different fitness landscapes in which galR was the target of different mutations: SNPs, deletions, and insertion of IS.• Key mutations in evolving mutants appeared and fixed at 48-72 h of cultivation.• ALE experiments led to increased understanding of the genetics of cellular adaptation to carbon source limitation.
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19
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Barco B, Clay NK. Hierarchical and Dynamic Regulation of Defense-Responsive Specialized Metabolism by WRKY and MYB Transcription Factors. FRONTIERS IN PLANT SCIENCE 2020; 10:1775. [PMID: 32082343 PMCID: PMC7005594 DOI: 10.3389/fpls.2019.01775] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 12/19/2019] [Indexed: 05/07/2023]
Abstract
The plant kingdom produces hundreds of thousands of specialized bioactive metabolites, some with pharmaceutical and biotechnological importance. Their biosynthesis and function have been studied for decades, but comparatively less is known about how transcription factors with overlapping functions and contrasting regulatory activities coordinately control the dynamics and output of plant specialized metabolism. Here, we performed temporal studies on pathogen-infected intact host plants with perturbed transcription factors. We identified WRKY33 as the condition-dependent master regulator and MYB51 as the dual functional regulator in a hierarchical gene network likely responsible for the gene expression dynamics and metabolic fluxes in the camalexin and 4-hydroxy-indole-3-carbonylnitrile (4OH-ICN) pathways. This network may have also facilitated the regulatory capture of the newly evolved 4OH-ICN pathway in Arabidopsis thaliana by the more-conserved transcription factor MYB51. It has long been held that the plasticity of plant specialized metabolism and the canalization of development should be differently regulated; our findings imply a common hierarchical regulatory architecture orchestrated by transcription factors for specialized metabolism and development, making it an attractive target for metabolic engineering.
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Affiliation(s)
| | - Nicole K. Clay
- Department of Molecular, Cellular & Developmental Biology, Yale University, New Haven, CT, United States
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20
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Alva A, Sabido-Ramos A, Escalante A, Bolívar F. New insights into transport capability of sugars and its impact on growth from novel mutants of Escherichia coli. Appl Microbiol Biotechnol 2020; 104:1463-1479. [PMID: 31900563 DOI: 10.1007/s00253-019-10335-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/12/2019] [Accepted: 12/27/2019] [Indexed: 12/27/2022]
Abstract
The fast-growing capability of Escherichia coli strains used to produce industrially relevant metabolites relies on their capability to transport efficiently glucose or potential industrial feedstocks such as sucrose or xylose as carbon sources. E. coli imports extracellular glucose into the periplasmic space across the outer membrane porins: OmpC, OmpF, and LamB. As the internal membrane is an impermeable barrier for sugars, the cell employs several primary and secondary active transport systems, and the phosphoenolpyruvate (PEP)-sugar phosphotransferase (PTS) system for glucose transport. PTS:glucose is the preferred system by E. coli to transport and phosphorylate the periplasmic glucose; nevertheless, PTS imposes a strict metabolic control mechanism on the preferential consumption of glucose over other carbon sources in sugar mixtures such as glucose and xylose resulting from the hydrolysis of lignocellulosic biomass, by the carbon catabolite repression. In this contribution, we summarize the major sugar transport systems for glucose and disaccharide transport, the exhibited substrate plasticity, and their impact on the growth of E. coli, highlighting the relevance of PTS in the control of the expression of genes for the transport and catabolism of other sugars as xylose. We discuss the strategies developed by evolved mutants of E. coli during adaptive laboratory evolution experiments to overcome the nutritional stress condition imposed by inactivation of PTS as a strategy for the selection of fast-growing derivatives in glucose, xylose, or mixtures of glucose:xylose. This approach results in the recruitment of other primary and secondary active transporters, demonstrating relevant sugar plasticity in derivative-evolved mutants. Elucidation of the molecular and biochemical basis of sugar-transport substrate plasticity represents a consistent approach for sugar-transport system engineering for the design of efficient E. coli derivative strains with improved substrate assimilation for biotechnological purposes.
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Affiliation(s)
- Alma Alva
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Andrea Sabido-Ramos
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Unidad Cuajimalpa, Ciudad de México, México
| | - Adelfo Escalante
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
| | - Francisco Bolívar
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
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21
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Abstract
How genomes are organized within cells and how the 3D architecture of a genome influences cellular functions are significant questions in biology. A bacterial genomic DNA resides inside cells in a highly condensed and functionally organized form called nucleoid (nucleus-like structure without a nuclear membrane). The Escherichia coli chromosome or nucleoid is composed of the genomic DNA, RNA, and protein. The nucleoid forms by condensation and functional arrangement of a single chromosomal DNA with the help of chromosomal architectural proteins and RNA molecules as well as DNA supercoiling. Although a high-resolution structure of a bacterial nucleoid is yet to come, five decades of research has established the following salient features of the E. coli nucleoid elaborated below: 1) The chromosomal DNA is on the average a negatively supercoiled molecule that is folded as plectonemic loops, which are confined into many independent topological domains due to supercoiling diffusion barriers; 2) The loops spatially organize into megabase size regions called macrodomains, which are defined by more frequent physical interactions among DNA sites within the same macrodomain than between different macrodomains; 3) The condensed and spatially organized DNA takes the form of a helical ellipsoid radially confined in the cell; and 4) The DNA in the chromosome appears to have a condition-dependent 3-D structure that is linked to gene expression so that the nucleoid architecture and gene transcription are tightly interdependent, influencing each other reciprocally. Current advents of high-resolution microscopy, single-molecule analysis and molecular structure determination of the components are expected to reveal the total structure and function of the bacterial nucleoid.
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Affiliation(s)
- Subhash C. Verma
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (SCV); (SLA)
| | - Zhong Qian
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sankar L. Adhya
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (SCV); (SLA)
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22
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McAuley M, Huang M, Timson DJ. Dynamic origins of substrate promiscuity in bacterial galactokinases. Carbohydr Res 2019; 486:107839. [PMID: 31704571 DOI: 10.1016/j.carres.2019.107839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/15/2019] [Accepted: 10/15/2019] [Indexed: 12/21/2022]
Abstract
Galactokinase catalyses the ATP-dependent phosphorylation of galactose and structurally related sugars. The enzyme has attracted interest as a potential biocatalyst for the production of sugar 1-phosphates and several attempts have been made to broaden its specificity. In general, bacterial galactokinases have wider substrate ranges than mammalian ones. The enzymes from Escherichia coli and Lactococcus lactis have received particular attention and a number of variants with increased promiscuity have been identified. Here, we present a molecular dynamics study designed to investigate the molecular causes of the wider substrate ranges of these enzymes and their variants with particular reference to protein mobility. Some regions close to the active site of the enzyme have different structures in the bacterial enzymes compared to the human one. Alterations known to increase the substrate range (e.g. Y371H in the E. coli enzyme), tend to alter the conformation of a key α-helical region (residues 216-232 in the E. coli enzyme). The equivalent helix in the human enzyme has previously been predicted to be altered in variants which affect catalytic activity or protein stability. This helix appears to be a key region in galactokinases from a range of species and may represent an interesting target for future attempts to broaden the specificity of galactokinases.
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Affiliation(s)
- Margaret McAuley
- School of Biological Sciences Queen's University Belfast, Medical Biology Building, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Meilan Huang
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, UK
| | - David J Timson
- School of Biological Sciences Queen's University Belfast, Medical Biology Building, 97 Lisburn Road, Belfast, BT9 7BL, UK; School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton, BN2 4GJ, UK.
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23
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Kurgan G, Sievert C, Flores A, Schneider A, Billings T, Panyon L, Morris C, Taylor E, Kurgan L, Cartwright R, Wang X. Parallel experimental evolution reveals a novel repressive control of GalP on xylose fermentation in Escherichia coli. Biotechnol Bioeng 2019; 116:2074-2086. [PMID: 31038200 PMCID: PMC11161036 DOI: 10.1002/bit.27004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/28/2019] [Accepted: 04/25/2019] [Indexed: 12/25/2022]
Abstract
Efficient xylose utilization will facilitate microbial conversion of lignocellulosic sugar mixtures into valuable products. In Escherichia coli, xylose catabolism is controlled by carbon catabolite repression (CCR). However, in E. coli such as the succinate-producing strain KJ122 with disrupted CCR, xylose utilization is still inhibited under fermentative conditions. To probe the underlying genetic mechanisms inhibiting xylose utilization, we evolved KJ122 to enhance its xylose fermentation abilities in parallel and characterized the potential convergent genetic changes shared by multiple independently evolved strains. Whole-genome sequencing revealed that convergent mutations occurred in the galactose regulon during adaptive laboratory evolution potentially decreasing the transcriptional level or the activity of GalP, a galactose permease. We showed that deletion of galP increased xylose utilization in both KJ122 and wild-type E. coli, demonstrating a common repressive role of GalP for xylose fermentation. Concomitantly, induced expression of galP from a plasmid repressed xylose fermentation. Transcriptome analysis using RNA sequencing indicates that galP inactivation increases transcription levels of many catabolic genes for secondary sugars including xylose and arabinose. The repressive role of GalP for fermenting secondary sugars in E. coli suggests that utilization of GalP as a substitute glucose transporter is undesirable for conversion of lignocellulosic sugar mixtures.
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Affiliation(s)
- Gavin Kurgan
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Christian Sievert
- School of Life Sciences, Arizona State University, Tempe, Arizona
- The Biodesign Institute, Arizona State University, Tempe, Arizona
| | - Andrew Flores
- Chemical Engineering Program, School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona
| | - Aidan Schneider
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Thomas Billings
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Larry Panyon
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Chandler Morris
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Eric Taylor
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Logan Kurgan
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Reed Cartwright
- School of Life Sciences, Arizona State University, Tempe, Arizona
- The Biodesign Institute, Arizona State University, Tempe, Arizona
| | - Xuan Wang
- School of Life Sciences, Arizona State University, Tempe, Arizona
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Crook N, Ferreiro A, Gasparrini AJ, Pesesky MW, Gibson MK, Wang B, Sun X, Condiotte Z, Dobrowolski S, Peterson D, Dantas G. Adaptive Strategies of the Candidate Probiotic E. coli Nissle in the Mammalian Gut. Cell Host Microbe 2019; 25:499-512.e8. [PMID: 30926240 PMCID: PMC6487504 DOI: 10.1016/j.chom.2019.02.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/06/2019] [Accepted: 02/19/2019] [Indexed: 12/14/2022]
Abstract
Probiotics are living microorganisms that are increasingly used as gastrointestinal therapeutics by virtue of their innate or engineered genetic function. Unlike abiotic therapeutics, probiotics can replicate in their intended site, subjecting their genomes and therapeutic properties to natural selection. We exposed the candidate probiotic E. coli Nissle (EcN) to the mouse gastrointestinal tract over several weeks, systematically altering the diet and background microbiota complexity. In-transit EcN accumulates genetic mutations that modulate carbohydrate utilization, stress response, and adhesion to gain competitive fitness, while previous exposure to antibiotics reveals an acquisition of resistance. We then leveraged these insights to generate an EcN strain that shows therapeutic efficacy in a mouse model of phenylketonuria and found that it was genetically stable over 1 week, thereby validating EcN's utility as a chassis for engineering. Collectively, we demonstrate a generalizable pipeline that can be applied to other probiotics to better understand their safety and engineering potential.
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Affiliation(s)
- Nathan Crook
- Equal Contribution
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Present address: Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27606, USA
| | - Aura Ferreiro
- Equal Contribution
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Andrew J. Gasparrini
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Present address: VL55, 55 Cambridge Pwky, Cambridge, MA 02142, USA
| | - Mitchell W. Pesesky
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Present address: Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Molly K. Gibson
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Present address: Flagship Pioneering, 55 Cambridge Pkwy, Cambridge, MA 02142, USA
| | - Bin Wang
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xiaoqing Sun
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zevin Condiotte
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Present address: Graduate School of Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stephen Dobrowolski
- Department of Pathology, Children’s Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA 15224, USA
| | - Daniel Peterson
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Present address: Eli Lilly & Company, 307 East McCarty Street, Indianapolis, IN 46225, USA
| | - Gautam Dantas
- The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Lead Contact: Gautam Dantas, Ph.D. ()
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Multiple Optimal Phenotypes Overcome Redox and Glycolytic Intermediate Metabolite Imbalances in Escherichia coli pgi Knockout Evolutions. Appl Environ Microbiol 2018; 84:AEM.00823-18. [PMID: 30054360 DOI: 10.1128/aem.00823-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 07/19/2018] [Indexed: 11/20/2022] Open
Abstract
A mechanistic understanding of how new phenotypes develop to overcome the loss of a gene product provides valuable insight on both the metabolic and regulatory functions of the lost gene. The pgi gene, whose product catalyzes the second step in glycolysis, was deleted in a growth-optimized Escherichia coli K-12 MG1655 strain. The initial knockout (KO) strain exhibited an 80% drop in growth rate that was largely recovered in eight replicate, but phenotypically distinct, cultures after undergoing adaptive laboratory evolution (ALE). Multi-omic data sets showed that the loss of pgi substantially shifted pathway usage, leading to a redox and sugar phosphate stress response. These stress responses were overcome by unique combinations of innovative mutations selected for by ALE. Thus, the coordinated mechanisms from genome to metabolome that lead to multiple optimal phenotypes after the loss of a major gene product were revealed.IMPORTANCE A mechanistic understanding of how microbes are able to overcome the loss of a gene through regulatory and metabolic changes is not well understood. Eight independent adaptive laboratory evolution (ALE) experiments with pgi knockout strains resulted in eight phenotypically distinct endpoints that were able to overcome the gene loss. Utilizing multi-omics analysis, the coordinated mechanisms from genome to metabolome that lead to multiple optimal phenotypes after the loss of a major gene product were revealed.
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Zhu F, Wang Y, San KY, Bennett GN. Metabolic engineering of Escherichia coli to produce succinate from soybean hydrolysate under anaerobic conditions. Biotechnol Bioeng 2018; 115:1743-1754. [PMID: 29508908 DOI: 10.1002/bit.26584] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 01/31/2018] [Accepted: 02/02/2018] [Indexed: 01/17/2023]
Abstract
It is of great economic interest to produce succinate from low-grade carbon sources, which can enhance the competitiveness of the biological route. In this study, succinate producer Escherichia coli CT550/pHL413KF1 was further engineered to efficiently use the mixed sugars from non-food based soybean hydrolysate to produce succinate under anaerobic conditions. Since many common E. coli strains fail to use galactose anaerobically even if they can use it aerobically, the glucose, and galactose related sugar transporters were deactivated individually and evaluated. The PTS system was found to be important for utilization of mixed sugars, and galactose uptake was activated by deactivating ptsG. In the ptsG- strain, glucose, and galactose were used simultaneously. Glucose was assimilated mainly through the mannose PTS system while galactose was transferred mainly through GalP in a ptsG- strain. A new succinate producing strain, FZ591C which can efficiently produce succinate from the mixed sugars present in soybean hydrolysate was constructed by integration of the high succinate yield producing module and the galactose utilization module into the chromosome of the CT550 ptsG- strain. The succinate yield reached 1.64 mol/mol hexose consumed (95% of maximum theoretical yield) when a mixed sugars feedstock was used as a carbon source. Based on the three monitored sugars, a nominal succinate yield of 1.95 mol/mol was observed as the strain can apparently also use some other minor sugars in the hydrolysate. In this study, we demonstrate that FZ591C can use soybean hydrolysate as an inexpensive carbon source for high yield succinate production under anaerobic conditions, giving it the potential for industrial application.
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Affiliation(s)
- Fayin Zhu
- Department of BioSciences, Rice University, Houston, Texas
| | - Yuanshan Wang
- Department of BioSciences, Rice University, Houston, Texas
- Institute of Bioengineering, Zhejiang University of Technology, Hangzhou, P. R. China
| | - Ka-Yiu San
- Department of Bioengineering, Rice University, Houston, Texas
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas
| | - George N Bennett
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas
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Bifidobacterium breve UCC2003 Employs Multiple Transcriptional Regulators To Control Metabolism of Particular Human Milk Oligosaccharides. Appl Environ Microbiol 2018; 84:AEM.02774-17. [PMID: 29500268 DOI: 10.1128/aem.02774-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/23/2018] [Indexed: 11/20/2022] Open
Abstract
Bifidobacterial carbohydrate metabolism has been studied in considerable detail for a variety of both plant- and human-derived glycans, particularly involving the bifidobacterial prototype strain Bifidobacterium breve UCC2003. We recently elucidated the metabolic pathways by which the human milk oligosaccharide (HMO) constituents lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT) and lacto-N-biose (LNB) are utilized by B. breve UCC2003. However, to date, no work has been carried out on the regulatory mechanisms that control the expression of the genetic loci involved in these HMO metabolic pathways. In this study, we describe the characterization of three transcriptional regulators and the corresponding operator and associated (inducible) promoter sequences, with the latter governing the transcription of the genetic elements involved in LN(n)T/LNB metabolism. The activity of these regulators is dependent on the release of specific monosaccharides, which are believed to act as allosteric effectors and which are derived from the corresponding HMOs targeted by the particular locus.IMPORTANCE Human milk oligosaccharides (HMOs) are a key factor in the development of the breastfed-infant microbiota. They function as prebiotics, selecting for a specific range of microbes, including a number of infant-associated species of bifidobacteria, which are thought to provide a range of health benefits to the infant host. While much research has been carried out on elucidating the mechanisms of HMO metabolism in infant-associated bifidobacteria, to date there is very little understanding of the transcriptional regulation of these pathways. This study reveals a multicomponent transcriptional regulation system that controls the recently identified pathways of HMO metabolism in the infant-associated Bifidobacterium breve prototype strain UCC2003. This not only provides insight into the regulatory mechanisms present in other infant-associated bifidobacteria but also provides an example of a network of sequential steps regulating microbial carbohydrate metabolism.
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A semi-synthetic regulon enables rapid growth of yeast on xylose. Nat Commun 2018; 9:1233. [PMID: 29581426 PMCID: PMC5964326 DOI: 10.1038/s41467-018-03645-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 03/01/2018] [Indexed: 01/27/2023] Open
Abstract
Nutrient assimilation is the first step that allows biological systems to proliferate and produce value-added products. Yet, implementation of heterologous catabolic pathways has so far relied on constitutive gene expression without consideration for global regulatory systems that may enhance nutrient assimilation and cell growth. In contrast, natural systems prefer nutrient-responsive gene regulation (called regulons) that control multiple cellular functions necessary for cell survival and growth. Here, in Saccharomyces cerevisiae, by partially- and fully uncoupling galactose (GAL)-responsive regulation and metabolism, we demonstrate the significant growth benefits conferred by the GAL regulon. Next, by adapting the various aspects of the GAL regulon for a non-native nutrient, xylose, we build a semi-synthetic regulon that exhibits higher growth rate, better nutrient consumption, and improved growth fitness compared to the traditional and ubiquitous constitutive expression strategy. This work provides an elegant paradigm to integrate non-native nutrient catabolism with native, global cellular responses to support fast growth. Efficient assimilation of nutrients is essential for the production of value-added products in microbial fermentation. Here the authors design a semi-synthetic xylose regulon to improve growth characteristics of Saccharomyces cerevisiae on this non-native sugar.
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Becker NA, Schwab TL, Clark KJ, Maher LJ. Bacterial gene control by DNA looping using engineered dimeric transcription activator like effector (TALE) proteins. Nucleic Acids Res 2018; 46:2690-2696. [PMID: 29390154 PMCID: PMC5861415 DOI: 10.1093/nar/gky047] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 01/07/2018] [Accepted: 01/18/2018] [Indexed: 01/04/2023] Open
Abstract
Genetic switches must alternate between states whose probabilities are dependent on regulatory signals. Classical examples of transcriptional control in bacteria depend on repressive DNA loops anchored by proteins whose structures are sensitive to small molecule inducers or co-repressors. We are interested in exploiting these natural principles to engineer artificial switches for transcriptional control of bacterial genes. Here, we implement designed homodimeric DNA looping proteins ('Transcription Activator-Like Effector Dimers'; TALEDs) for this purpose in living bacteria. Using well-studied FKBP dimerization domains, we build switches that mimic regulatory characteristics of classical Escherichia coli lactose, galactose and tryptophan operon promoters, including induction or co-repression by small molecules. Engineered DNA looping using TALEDs is thus a new approach to tuning gene expression in bacteria. Similar principles may also be applicable for gene control in eukaryotes.
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Affiliation(s)
- Nicole A Becker
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, 200 First St. SW, Rochester, MN 55905, USA
| | - Tanya L Schwab
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, 200 First St. SW, Rochester, MN 55905, USA
| | - Karl J Clark
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, 200 First St. SW, Rochester, MN 55905, USA
| | - L. James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, 200 First St. SW, Rochester, MN 55905, USA
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30
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Rate-limiting steps in transcription dictate sensitivity to variability in cellular components. Sci Rep 2017; 7:10588. [PMID: 28878283 PMCID: PMC5587725 DOI: 10.1038/s41598-017-11257-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 08/21/2017] [Indexed: 12/28/2022] Open
Abstract
Cell-to-cell variability in cellular components generates cell-to-cell diversity in RNA and protein production dynamics. As these components are inherited, this should also cause lineage-to-lineage variability in these dynamics. We conjectured that these effects on transcription are promoter initiation kinetics dependent. To test this, first we used stochastic models to predict that variability in the numbers of molecules involved in upstream processes, such as the intake of inducers from the environment, acts only as a transient source of variability in RNA production numbers, while variability in the numbers of a molecular species controlling transcription of an active promoter acts as a constant source. Next, from single-cell, single-RNA level time-lapse microscopy of independent lineages of Escherichia coli cells, we demonstrate the existence of lineage-to-lineage variability in gene activation times and mean RNA production rates, and that these variabilities differ between promoters and inducers used. Finally, we provide evidence that this can be explained by differences in the kinetics of the rate-limiting steps in transcription between promoters and induction schemes. We conclude that cell-to-cell and consequent lineage-to-lineage variability in RNA and protein numbers are both promoter sequence-dependent and subject to regulation.
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31
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Ravcheev DA, Thiele I. Comparative Genomic Analysis of the Human Gut Microbiome Reveals a Broad Distribution of Metabolic Pathways for the Degradation of Host-Synthetized Mucin Glycans and Utilization of Mucin-Derived Monosaccharides. Front Genet 2017; 8:111. [PMID: 28912798 PMCID: PMC5583593 DOI: 10.3389/fgene.2017.00111] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 08/11/2017] [Indexed: 12/27/2022] Open
Abstract
The colonic mucus layer is a dynamic and complex structure formed by secreted and transmembrane mucins, which are high-molecular-weight and heavily glycosylated proteins. Colonic mucus consists of a loose outer layer and a dense epithelium-attached layer. The outer layer is inhabited by various representatives of the human gut microbiota (HGM). Glycans of the colonic mucus can be used by the HGM as a source of carbon and energy when dietary fibers are not sufficiently available. Both commensals and pathogens can utilize mucin glycans. Commensals are mostly involved in the cleavage of glycans, while pathogens mostly utilize monosaccharides released by commensals. This HGM-derived degradation of the mucus layer increases pathogen susceptibility and causes many other health disorders. Here, we analyzed 397 individual HGM genomes to identify pathways for the cleavage of host-synthetized mucin glycans to monosaccharides as well as for the catabolism of the derived monosaccharides. Our key results are as follows: (i) Genes for the cleavage of mucin glycans were found in 86% of the analyzed genomes, which significantly higher than a previous estimation. (ii) Genes for the catabolism of derived monosaccharides were found in 89% of the analyzed genomes. (iii) Comparative genomic analysis identified four alternative forms of the monosaccharide-catabolizing enzymes and four alternative forms of monosaccharide transporters. (iv) Eighty-five percent of the analyzed genomes may be involved in potential feeding pathways for the monosaccharides derived from cleaved mucin glycans. (v) The analyzed genomes demonstrated different abilities to degrade known mucin glycans. Generally, the ability to degrade at least one type of mucin glycan was predicted for 81% of the analyzed genomes. (vi) Eighty-two percent of the analyzed genomes can form mutualistic pairs that are able to degrade mucin glycans and are not degradable by any of the paired organisms alone. Taken together, these findings provide further insight into the inter-microbial communications of the HGM as well as into host-HGM interactions.
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Affiliation(s)
- Dmitry A Ravcheev
- Luxembourg Centre for Systems Biomedicine, University of LuxembourgEsch-sur-Alzette, Luxembourg
| | - Ines Thiele
- Luxembourg Centre for Systems Biomedicine, University of LuxembourgEsch-sur-Alzette, Luxembourg
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32
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Leng F. Protein-induced DNA linking number change by sequence-specific DNA binding proteins and its biological effects. Biophys Rev 2017; 8:123-133. [PMID: 28510217 DOI: 10.1007/s12551-016-0239-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/27/2016] [Indexed: 12/18/2022] Open
Abstract
Sequence-specific DNA-binding proteins play essential roles in many fundamental biological events such as DNA replication, recombination, and transcription. One common feature of sequence-specific DNA-binding proteins is to introduce structural changes to their DNA recognition sites including DNA-bending and DNA linking number change (ΔLk). In this article, I review recent progress in studying protein-induced ΔLk by several sequence-specific DNA-binding proteins, such as E. coli cAMP receptor protein (CRP) and lactose repressor (LacI). It was demonstrated recently that protein-induced ΔLk is an intrinsic property for sequence-specific DNA-binding proteins and does not correlate to protein-induced other structural changes, such as DNA bending. For instance, although CRP bends its DNA recognition site by 90°, it was not able to introduce a ΔLk to it. However, LacI was able to simultaneously bend and introduce a ΔLk to its DNA binding sites. Intriguingly, LacI also constrained superhelicity within LacI-lac O1 complexes if (-) supercoiled DNA templates were provided. I also discuss how protein-induced ΔLk help sequence-specific DNA-binding proteins regulate their biological functions. For example, it was shown recently that LacI utilizes the constrained superhelicity (ΔLk) in LacI-lac O1 complexes and serves as a topological barrier to constrain free, unconstrained (-) supercoils within the 401-bp DNA loop. These constrained (-) supercoils enhance LacI's binding affinity and therefore the repression of the lac promoter. Other biological functions include how DNA replication initiators λ O and DnaA use the induced ΔLk to open/melt bacterial DNA replication origins.
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Affiliation(s)
- Fenfei Leng
- Biomolecular Sciences Institute and Department of Chemistry & Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA.
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33
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Li H, Zhang L, Guo W, Xu D. Development of a genetically engineered Escherichia coli strain for plasmid transformation in Corynebacterium glutamicum. J Microbiol Methods 2016; 131:156-160. [DOI: 10.1016/j.mimet.2016.10.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 10/24/2016] [Accepted: 10/24/2016] [Indexed: 10/20/2022]
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34
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Qian Z, Trostel A, Lewis DEA, Lee SJ, He X, Stringer AM, Wade JT, Schneider TD, Durfee T, Adhya S. Genome-Wide Transcriptional Regulation and Chromosome Structural Arrangement by GalR in E. coli. Front Mol Biosci 2016; 3:74. [PMID: 27900321 PMCID: PMC5110547 DOI: 10.3389/fmolb.2016.00074] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 10/26/2016] [Indexed: 11/13/2022] Open
Abstract
The regulatory protein, GalR, is known for controlling transcription of genes related to D-galactose metabolism in Escherichia coli. Here, using a combination of experimental and bioinformatic approaches, we identify novel GalR binding sites upstream of several genes whose function is not directly related to D-galactose metabolism. Moreover, we do not observe regulation of these genes by GalR under standard growth conditions. Thus, our data indicate a broader regulatory role for GalR, and suggest that regulation by GalR is modulated by other factors. Surprisingly, we detect regulation of 158 transcripts by GalR, with few regulated genes being associated with a nearby GalR binding site. Based on our earlier observation of long-range interactions between distally bound GalR dimers, we propose that GalR indirectly regulates the transcription of many genes by inducing large-scale restructuring of the chromosome.
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Affiliation(s)
- Zhong Qian
- Laboratory of Molecular Biology, National Institutes of Health, National Cancer Institute Bethesda, MD, USA
| | - Andrei Trostel
- Laboratory of Molecular Biology, National Institutes of Health, National Cancer Institute Bethesda, MD, USA
| | - Dale E A Lewis
- Laboratory of Molecular Biology, National Institutes of Health, National Cancer Institute Bethesda, MD, USA
| | - Sang Jun Lee
- Microbiomics and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology Daejeon, Korea
| | - Ximiao He
- Laboratory of Metabolism, National Institutes of Health, National Cancer Institute Bethesda, MD, USA
| | - Anne M Stringer
- Wadsworth Center, New York State Department of Health Albany, NY, USA
| | - Joseph T Wade
- Wadsworth Center, New York State Department of HealthAlbany, NY, USA; Department of Biomedical Sciences, School of Public Health, University of AlbanyAlbany, NY, USA
| | - Thomas D Schneider
- Gene Regulation and Chromosome Biology Laboratory, National Institutes of Health, National Cancer Institute, Center for Cancer Research Frederick, MD, USA
| | | | - Sankar Adhya
- Laboratory of Molecular Biology, National Institutes of Health, National Cancer Institute Bethesda, MD, USA
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35
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Olajuyin AM, Yang M, Liu Y, Mu T, Tian J, Adaramoye OA, Xing J. Efficient production of succinic acid from Palmaria palmata hydrolysate by metabolically engineered Escherichia coli. BIORESOURCE TECHNOLOGY 2016; 214:653-659. [PMID: 27203224 DOI: 10.1016/j.biortech.2016.04.117] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 06/05/2023]
Abstract
Succinic acid, a C4 dicarboxylic acid is used in many fields such as food, agriculture, pharmaceutical and polymer industries. In this study, microbial production of succinic acid from Palmaria palmata was investigated for the first time. In engineered Escherichia coli KLPPP, lactate dehydrogenase, pyruvate formate lyase, phosphotransacetylase-acetate kinase and pyruvate oxidase genes were deleted while phosphoenolpyruvate carboxykinase was overexpressed. The recombinant exhibited higher molar yield of succinic acid on galactose (1.20±0.02mol/mol) than glucose (0.48±0.03mol/mol). The concentration and molar yield of succinic acid were 22.40±0.12g/L and 1.13±0.02mol/mol total sugar respectively after 72h dual phase fermentation from P. palmata hydrolysate which composed of glucose (12.57±0.17g/L) and galactose (18.03±0.10g/L). The results demonstrate that P. palmata red macroalgae biomass represents a novel and an economically alternative feedstock for biochemicals production.
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Affiliation(s)
- Ayobami Matthew Olajuyin
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Maohua Yang
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Yilan Liu
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Tingzhen Mu
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiangnan Tian
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | | | - Jianmin Xing
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
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36
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Leng F. Protein-induced DNA linking number change by sequence-specific DNA binding proteins and its biological effects. Biophys Rev 2016; 8:197-207. [PMID: 28510223 DOI: 10.1007/s12551-016-0204-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/27/2016] [Indexed: 12/15/2022] Open
Abstract
Sequence-specific DNA-binding proteins play essential roles in many fundamental biological events such as DNA replication, recombination, and transcription. One common feature of sequence-specific DNA-binding proteins is to introduce structural changes to their DNA recognition sites including DNA-bending and DNA linking number change (ΔLk). In this article, I review recent progress in studying protein-induced ΔLk by several sequence-specific DNA-binding proteins, such as E. coli cAMP receptor protein (CRP) and lactose repressor (LacI). It was demonstrated recently that protein-induced ΔLk is an intrinsic property for sequence-specific DNA-binding proteins and does not correlate to protein-induced other structural changes, such as DNA bending. For instance, although CRP bends its DNA recognition site by 90°, it was not able to introduce a ΔLk to it. However, LacI was able to simultaneously bend and introduce a ΔLk to its DNA binding sites. Intriguingly, LacI also constrained superhelicity within LacI-lac O1 complexes if (-) supercoiled DNA templates were provided. I also discuss how protein-induced ΔLk help sequence-specific DNA-binding proteins regulate their biological functions. For example, it was shown recently that LacI utilizes the constrained superhelicity (ΔLk) in LacI-lac O1 complexes and serves as a topological barrier to constrain free, unconstrained (-) supercoils within the 401-bp DNA loop. These constrained (-) supercoils enhance LacI's binding affinity and therefore the repression of the lac promoter. Other biological functions include how DNA replication initiators λ O and DnaA use the induced ΔLk to open/melt bacterial DNA replication origins.
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Affiliation(s)
- Fenfei Leng
- Biomolecular Sciences Institute and Department of Chemistry & Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA.
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37
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Afroz T, Luo ML, Beisel CL. Impact of Residual Inducer on Titratable Expression Systems. PLoS One 2015; 10:e0137421. [PMID: 26348036 PMCID: PMC4562711 DOI: 10.1371/journal.pone.0137421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 08/17/2015] [Indexed: 11/19/2022] Open
Abstract
Inducible expression systems are widely employed for the titratable control of gene expression, yet molecules inadvertently present in the growth medium or synthesized by the host cells can alter the response profile of some of these systems. Here, we explored the quantitative impact of these residual inducers on the apparent response properties of inducible systems. Using a simple mathematical model, we found that the presence of residual inducer shrinks the apparent dynamic range and causes the apparent Hill coefficient to converge to one. We also found that activating systems were more sensitive than repressing systems to the presence of residual inducer and the response parameters were most heavily dependent on the original Hill coefficient. Experimental interrogation of common titratable systems based on an L-arabinose inducible promoter or a thiamine pyrophosphate-repressing riboswitch in Escherichia coli confirmed the predicted trends. We finally found that residual inducer had a distinct effect on "all-or-none" systems, which exhibited increased sensitivity to the added inducer until becoming fully induced. Our findings indicate that residual inducer or repressor alters the quantitative response properties of titratable systems, impacting their utility for scientific discovery and pathway engineering.
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Affiliation(s)
- Taliman Afroz
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Michelle L Luo
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Chase L Beisel
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, United States of America
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38
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Patterson AG, Chang JT, Taylor C, Fineran PC. Regulation of the Type I-F CRISPR-Cas system by CRP-cAMP and GalM controls spacer acquisition and interference. Nucleic Acids Res 2015; 43:6038-48. [PMID: 26007654 PMCID: PMC4499141 DOI: 10.1093/nar/gkv517] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/06/2015] [Indexed: 12/22/2022] Open
Abstract
The CRISPR-Cas prokaryotic ‘adaptive immune systems’ represent a sophisticated defence strategy providing bacteria and archaea with protection from invading genetic elements, such as bacteriophages or plasmids. Despite intensive research into their mechanism and application, how CRISPR-Cas systems are regulated is less clear, and nothing is known about the regulation of Type I-F systems. We used Pectobacterium atrosepticum, a Gram-negative phytopathogen, to study CRISPR-Cas regulation, since it contains a single Type I-F system. The CRP-cAMP complex activated the cas operon, increasing the expression of the adaptation genes cas1 and cas2–3 in addition to the genes encoding the Csy surveillance complex. Mutation of crp or cyaA (encoding adenylate cyclase) resulted in reductions in both primed spacer acquisition and interference. Furthermore, we identified a galactose mutarotase, GalM, which reduced cas operon expression in a CRP- and CyaA-dependent manner. We propose that the Type I-F system senses metabolic changes, such as sugar availability, and regulates cas genes to initiate an appropriate defence response. Indeed, elevated glucose levels reduced cas expression in a CRP- and CyaA-dependent manner. Taken together, these findings highlight that a metabolite-sensing regulatory pathway controls expression of the Type I-F CRISPR-Cas system to modulate levels of adaptation and interference.
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Affiliation(s)
- Adrian G Patterson
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - James T Chang
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Corinda Taylor
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Peter C Fineran
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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39
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Baumgärtner F, Sprenger GA, Albermann C. Galactose-limited fed-batch cultivation of Escherichia coli for the production of lacto-N-tetraose. Enzyme Microb Technol 2015; 75-76:37-43. [PMID: 26047914 DOI: 10.1016/j.enzmictec.2015.04.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/22/2015] [Indexed: 02/08/2023]
Abstract
Lacto-N-tetraose (Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc) is one of the most abundant oligosaccharide structures in human milk. We recently described the synthesis of lacto-N-tetraose by a whole-cell biotransformation with recombinant Escherichia coli cells. However, only about 5% of the lactose was converted into lacto-N-tetraose by this approach. The major product obtained was the intermediate lacto-N-triose II (GlcNAc(β1-3)Gal(β1-4)Glc). In order to improve the bioconversion of lactose to lacto-N-tetraose, we have investigated the influence of the carbon source on the formation of lacto-N-tetraose and on the intracellular availability of the glycosyltransferase substrates, UDP-N-acetylglucosamine and UDP-galactose. By growth of the recombinant E. coli cells on D-galactose, the yield of lacto-N-tetraose (810.8 mg L(-1) culture) was 3.6-times higher compared to cultivation on D-glucose. Using fed-batch cultivation with galactose as sole energy and carbon source, a large-scale synthesis of lacto-N-tetraose was demonstrated. During the 26 h feeding phase the growth rate (μ = 0.05) was maintained by an exponential galactose feed. In total, 16 g L(-1) lactose were fed and resulted in final yields of 12.72 ± 0.21 g L(-1) lacto-N-tetraose and 13.70 ± 0.10 g L(-1) lacto-N-triose II. In total, 173 g of lacto-N-tetraose were produced with a space-time yield of 0.37 g L(-1) h(-1).
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Affiliation(s)
- Florian Baumgärtner
- Institute of Microbiology, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Georg A Sprenger
- Institute of Microbiology, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Christoph Albermann
- Institute of Microbiology, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
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40
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Afroz T, Biliouris K, Boykin KE, Kaznessis Y, Beisel CL. Trade-offs in engineering sugar utilization pathways for titratable control. ACS Synth Biol 2015; 4:141-9. [PMID: 24735079 PMCID: PMC4384834 DOI: 10.1021/sb400162z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
Titratable
systems are common tools in metabolic engineering to
tune the levels of enzymes and cellular components as part of pathway
optimization. For nonmodel microorganisms with limited genetic tools,
inducible sugar utilization pathways offer built-in titratable systems.
However, these pathways can exhibit undesirable single-cell behaviors
that hamper the uniform and tunable control of gene expression. Here,
we applied mathematical modeling and single-cell measurements of l-arabinose utilization in Escherichia coli to systematically explore how sugar utilization pathways can be
altered to achieve desirable inducible properties. We found that different
pathway alterations, such as the removal of catabolism, constitutive
expression of high-affinity or low-affinity transporters, or further
deletion of the other transporters, came with trade-offs specific
to each alteration. For instance, sugar catabolism improved the uniformity
and linearity of the response at the cost of requiring higher sugar
concentrations to induce the pathway. Within these alterations, we
also found that a uniform and linear response could be achieved with
a single alteration: constitutively expressing the high-affinity transporter.
Equivalent modifications to the d-xylose utilization pathway
yielded similar responses, demonstrating the applicability of our
observations. Overall, our findings indicate that there is no ideal
set of typical alterations when co-opting natural utilization pathways
for titratable control and suggest design rules for manipulating these
pathways to advance basic genetic studies and the metabolic engineering
of microorganisms for optimized chemical production.
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Affiliation(s)
- Taliman Afroz
- Department
of Chemical and Biomolecular Engineering North Carolina State University Raleigh, North Carolina 27695, United States
| | - Konstantinos Biliouris
- Department
of Chemical Engineering and Materials Science University of Minnesota Minneapolis, Minnesota 55455, United States
| | - Kelsey E. Boykin
- Department
of Chemical and Biomolecular Engineering North Carolina State University Raleigh, North Carolina 27695, United States
| | - Yiannis Kaznessis
- Department
of Chemical Engineering and Materials Science University of Minnesota Minneapolis, Minnesota 55455, United States
| | - Chase L. Beisel
- Department
of Chemical and Biomolecular Engineering North Carolina State University Raleigh, North Carolina 27695, United States
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41
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Wang P, Lü J, Yu X. Identification of important nodes in directed biological networks: a network motif approach. PLoS One 2014; 9:e106132. [PMID: 25170616 PMCID: PMC4149525 DOI: 10.1371/journal.pone.0106132] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 08/03/2014] [Indexed: 11/18/2022] Open
Abstract
Identification of important nodes in complex networks has attracted an increasing attention over the last decade. Various measures have been proposed to characterize the importance of nodes in complex networks, such as the degree, betweenness and PageRank. Different measures consider different aspects of complex networks. Although there are numerous results reported on undirected complex networks, few results have been reported on directed biological networks. Based on network motifs and principal component analysis (PCA), this paper aims at introducing a new measure to characterize node importance in directed biological networks. Investigations on five real-world biological networks indicate that the proposed method can robustly identify actually important nodes in different networks, such as finding command interneurons, global regulators and non-hub but evolutionary conserved actually important nodes in biological networks. Receiver Operating Characteristic (ROC) curves for the five networks indicate remarkable prediction accuracy of the proposed measure. The proposed index provides an alternative complex network metric. Potential implications of the related investigations include identifying network control and regulation targets, biological networks modeling and analysis, as well as networked medicine.
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Affiliation(s)
- Pei Wang
- School of Mathematics and Information Sciences, Henan University, Kaifeng, China
- School of Electrical and Computer Engineering, RMIT University, Melbourne, Victoria, Australia
- * E-mail:
| | - Jinhu Lü
- Institute of Systems Science, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing, China
| | - Xinghuo Yu
- School of Electrical and Computer Engineering, RMIT University, Melbourne, Victoria, Australia
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42
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Rao CV, Koirala S. Black and white with some shades of grey: the diverse responses of inducible metabolic pathways in Escherichia coli. Mol Microbiol 2014; 93:1079-83. [PMID: 25069377 DOI: 10.1111/mmi.12734] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2014] [Indexed: 01/17/2023]
Abstract
The metabolic pathways for many sugars are inducible. This process has been extensively studied in the case of Escherichia coli lactose metabolism. It has long been known that gratuitous induction of the lac operon with non-metabolizable lactose analogues generates an all-or-nothing response, where some cells express the lac genes at a maximal rate and others not at all. However, the response to lactose itself is graded, where all cells express the lac genes in proportion to lactose concentrations. The mechanisms generating these distinct behaviours in lactose metabolism have been a topic of many studies. Despite this large body of work, little is known about how other pathways respond to their cognate sugars. An article of Molecular Microbiology investigated the response of eight metabolic pathways in E. coli to their cognate sugars at single-cell resolution. The authors demonstrate that these pathways exhibit diverse responses, ranging from graded to all-or-nothing responses and combinations thereof. Remarkably, they were able to interpret these responses using a simple mathematical model and identify the mechanisms likely giving rise to each.
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Affiliation(s)
- Christopher V Rao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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43
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Becker NA, Greiner AM, Peters JP, Maher LJ. Bacterial promoter repression by DNA looping without protein-protein binding competition. Nucleic Acids Res 2014; 42:5495-504. [PMID: 24598256 PMCID: PMC4027209 DOI: 10.1093/nar/gku180] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The Escherichia coli lactose operon provides a paradigm for understanding gene control by DNA looping where the lac repressor (LacI) protein competes with RNA polymerase for DNA binding. Not all promoter loops involve direct competition between repressor and RNA polymerase. This raises the possibility that positioning a promoter within a tightly constrained DNA loop is repressive per se, an idea that has previously only been considered in vitro. Here, we engineer living E. coli bacteria to measure repression due to promoter positioning within such a tightly constrained DNA loop in the absence of protein–protein binding competition. We show that promoters held within such DNA loops are repressed ∼100-fold, with up to an additional ∼10-fold repression (∼1000-fold total) dependent on topological positioning of the promoter on the inner or outer face of the DNA loop. Chromatin immunoprecipitation data suggest that repression involves inhibition of both RNA polymerase initiation and elongation. These in vivo results show that gene repression can result from tightly looping promoter DNA even in the absence of direct competition between repressor and RNA polymerase binding.
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Affiliation(s)
- Nicole A Becker
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905, USA
| | - Alexander M Greiner
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905, USA Luther College, Departments of Biology and Chemistry, Decorah, IA 52101, USA
| | - Justin P Peters
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905, USA
| | - L James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905, USA
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44
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Rydenfelt M, Cox RS, Garcia H, Phillips R. Statistical mechanical model of coupled transcription from multiple promoters due to transcription factor titration. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:012702. [PMID: 24580252 PMCID: PMC4043999 DOI: 10.1103/physreve.89.012702] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 10/04/2013] [Indexed: 06/03/2023]
Abstract
Transcription factors (TFs) with regulatory action at multiple promoter targets is the rule rather than the exception, with examples ranging from the cAMP receptor protein (CRP) in E. coli that regulates hundreds of different genes simultaneously to situations involving multiple copies of the same gene, such as plasmids, retrotransposons, or highly replicated viral DNA. When the number of TFs heavily exceeds the number of binding sites, TF binding to each promoter can be regarded as independent. However, when the number of TF molecules is comparable to the number of binding sites, TF titration will result in correlation ("promoter entanglement") between transcription of different genes. We develop a statistical mechanical model which takes the TF titration effect into account and use it to predict both the level of gene expression for a general set of promoters and the resulting correlation in transcription rates of different genes. Our results show that the TF titration effect could be important for understanding gene expression in many regulatory settings.
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Affiliation(s)
- Mattias Rydenfelt
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
| | - Robert Sidney Cox
- Technology Research Association of Highly Efficient Gene Design, Kobe University, Hyogo 657-8501, Japan
| | - Hernan Garcia
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Rob Phillips
- Department of Applied Physics, California Institute of Technology, Pasadena, California 91125, USA and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
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45
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Mäkelä J, Kandhavelu M, Oliveira SMD, Chandraseelan JG, Lloyd-Price J, Peltonen J, Yli-Harja O, Ribeiro AS. In vivo single-molecule kinetics of activation and subsequent activity of the arabinose promoter. Nucleic Acids Res 2013; 41:6544-52. [PMID: 23644285 PMCID: PMC3711423 DOI: 10.1093/nar/gkt350] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Using a single-RNA detection technique in live Escherichia coli cells, we measure, for each cell, the waiting time for the production of the first RNA under the control of PBAD promoter after induction by arabinose, and subsequent intervals between transcription events. We find that the kinetics of the arabinose intake system affect mean and diversity in RNA numbers, long after induction. We observed the same effect on Plac/ara-1 promoter, which is inducible by arabinose or by IPTG. Importantly, the distribution of waiting times of Plac/ara-1 is indistinguishable from that of PBAD, if and only if induced by arabinose alone. Finally, RNA production under the control of PBAD is found to be a sub-Poissonian process. We conclude that inducer-dependent waiting times affect mean and cell-to-cell diversity in RNA numbers long after induction, suggesting that intake mechanisms have non-negligible effects on the phenotypic diversity of cell populations in natural, fluctuating environments.
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Affiliation(s)
- Jarno Mäkelä
- Laboratory of Biosystem Dynamics, Computational Systems Biology Research Group, Department of Signal Processing, Tampere University of Technology, FI-33101 Tampere, Finland
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46
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Karton-Lifshin N, Vogel U, Sella E, Seeberger PH, Shabat D, Lepenies B. Enzyme-mediated nutrient release: glucose-precursor activation by β-galactosidase to induce bacterial growth. Org Biomol Chem 2013; 11:2903-10. [PMID: 23519143 DOI: 10.1039/c3ob27385g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bacteria will gain an advantage if they are able to metabolize nutrients that are inaccessible for other bacteria. To demonstrate this principle, we developed a simple model system, which mimics how bacteria exploit natural carbon sources. A masked glucose precursor that is activated by β-galactosidase was used as a carbon source for bacterial growth in a glucose-deficient medium. No bacterial growth was observed in the presence of control substances in which β-galactosidase mediated cleavage did not lead to glucose release. This study represents a proof-of-principle example in which a bacterium can grow in a nutrient-free medium by inducible, enzyme-mediated nutrient release from a precursor.
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Affiliation(s)
- Naama Karton-Lifshin
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences and Tel Aviv University, Tel Aviv, 69978, Israel
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47
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Solomon KV, Moon TS, Ma B, Sanders TM, Prather KLJ. Tuning primary metabolism for heterologous pathway productivity. ACS Synth Biol 2013; 2:126-35. [PMID: 23656436 DOI: 10.1021/sb300055e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tuning expression of competing endogenous pathways has been identified as an effective strategy in the optimization of heterologous production pathways. However, intervention at the first step of glycolysis, where no alternate routes of carbon utilization exist, remains unexplored. In this work we have engineered a viable E. coli host that decouples glucose transport and phosphorylation, enabling independent control of glucose flux to a heterologous pathway of interest through glucokinase (glk) expression. Using community sourced and curated promoters, glk expression was varied over a 3-fold range while maintaining cellular viability. The effects of glk expression on the productivity of a model glucose-consuming pathway were also studied. Through control of glycolytic flux we were able to explore a number of cellular phenotypes and vary the yield of our model pathway by up to 2-fold in a controllable manner.
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Affiliation(s)
- Kevin V. Solomon
- Department of Chemical Engineering,
Synthetic Biology Engineering Research Center (SynBERC), Massachusetts Institute of Technology, Cambridge, Massachusetts
02139, United States
| | - Tae Seok Moon
- Department of Chemical Engineering,
Synthetic Biology Engineering Research Center (SynBERC), Massachusetts Institute of Technology, Cambridge, Massachusetts
02139, United States
| | - Brian Ma
- Department of Chemical Engineering,
Synthetic Biology Engineering Research Center (SynBERC), Massachusetts Institute of Technology, Cambridge, Massachusetts
02139, United States
- California
Institute of Technology
Summer Undergraduate Research Fellow (SURF), Department of Bioengineering, California Institute of Technology, Pasadena, California
91125, United States
| | - Tarielle M. Sanders
- Department of Chemical Engineering,
Synthetic Biology Engineering Research Center (SynBERC), Massachusetts Institute of Technology, Cambridge, Massachusetts
02139, United States
- Amgen
Scholars Program, Department
of Chemistry, Norfolk State University,
Norfolk, Virginia 23504, United States
| | - Kristala L. J. Prather
- Department of Chemical Engineering,
Synthetic Biology Engineering Research Center (SynBERC), Massachusetts Institute of Technology, Cambridge, Massachusetts
02139, United States
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48
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Surface Growth of a Motile Bacterial Population Resembles Growth in a Chemostat. J Mol Biol 2012; 424:180-91. [DOI: 10.1016/j.jmb.2012.09.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 09/02/2012] [Accepted: 09/06/2012] [Indexed: 11/17/2022]
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49
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Galactose repressor mediated intersegmental chromosomal connections in Escherichia coli. Proc Natl Acad Sci U S A 2012; 109:11336-41. [PMID: 22733746 DOI: 10.1073/pnas.1208595109] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
By microscopic analysis of fluorescent-labeled GalR, a regulon-specific transcription factor in Escherichia coli, we observed that GalR is present in the cell as aggregates (one to three fluorescent foci per cell) in nongrowing cells. To investigate whether these foci represent GalR-mediated association of some of the GalR specific DNA binding sites (gal operators), we used the chromosome conformation capture (3C) method in vivo. Our 3C data demonstrate that, in stationary phase cells, many of the operators distributed around the chromosome are interacted. By the use of atomic force microscopy, we showed that the observed remote chromosomal interconnections occur by direct interactions between DNA-bound GalR not involving any other factors. Mini plasmid DNA circles with three or five operators positioned at defined loci showed GalR-dependent loops of expected sizes of the intervening DNA segments. Our findings provide unique evidence that a transcription factor participates in organizing the chromosome in a three-dimensional structure. We believe that these chromosomal connections increase local concentration of GalR for coordinating the regulation of widely separated target genes, and organize the chromosome structure in space, thereby likely contributing to chromosome compaction.
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50
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Didelot X, Méric G, Falush D, Darling AE. Impact of homologous and non-homologous recombination in the genomic evolution of Escherichia coli. BMC Genomics 2012; 13:256. [PMID: 22712577 PMCID: PMC3505186 DOI: 10.1186/1471-2164-13-256] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 05/30/2012] [Indexed: 11/10/2022] Open
Abstract
Background Escherichia coli is an important species of bacteria that can live as a harmless inhabitant of the guts of many animals, as a pathogen causing life-threatening conditions or freely in the non-host environment. This diversity of lifestyles has made it a particular focus of interest for studies of genetic variation, mainly with the aim to understand how a commensal can become a deadly pathogen. Many whole genomes of E. coli have been fully sequenced in the past few years, which offer helpful data to help understand how this important species evolved. Results We compared 27 whole genomes encompassing four phylogroups of Escherichia coli (A, B1, B2 and E). From the core-genome we established the clonal relationships between the isolates as well as the role played by homologous recombination during their evolution from a common ancestor. We found strong evidence for sexual isolation between three lineages (A+B1, B2, E), which could be explained by the ecological structuring of E. coli and may represent on-going speciation. We identified three hotspots of homologous recombination, one of which had not been previously described and contains the aroC gene, involved in the essential shikimate metabolic pathway. We also described the role played by non-homologous recombination in the pan-genome, and showed that this process was highly heterogeneous. Our analyses revealed in particular that the genomes of three enterohaemorrhagic (EHEC) strains within phylogroup B1 have converged from originally separate backgrounds as a result of both homologous and non-homologous recombination. Conclusions Recombination is an important force shaping the genomic evolution and diversification of E. coli, both by replacing fragments of genes with an homologous sequence and also by introducing new genes. In this study, several non-random patterns of these events were identified which correlated with important changes in the lifestyle of the bacteria, and therefore provide additional evidence to explain the relationship between genomic variation and ecological adaptation.
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Affiliation(s)
- Xavier Didelot
- Department of Infectious Disease Epidemiology, Imperial College, Norfolk Place, London W2 1PG, UK.
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