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Lamoureux CR, Phaneuf PV, Palsson B, Zielinski D. Escherichia coli non-coding regulatory regions are highly conserved. NAR Genom Bioinform 2024; 6:lqae041. [PMID: 38774514 PMCID: PMC11106028 DOI: 10.1093/nargab/lqae041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 04/05/2024] [Accepted: 05/15/2024] [Indexed: 05/24/2024] Open
Abstract
Microbial genome sequences are rapidly accumulating, enabling large-scale studies of sequence variation. Existing studies primarily focus on coding regions to study amino acid substitution patterns in proteins. However, non-coding regulatory regions also play a distinct role in determining physiologic responses. To investigate intergenic sequence variation on a large-scale, we identified non-coding regulatory region alleles across 2350 Escherichia coli strains. This 'alleleome' consists of 117 781 unique alleles for 1169 reference regulatory regions (transcribing 1975 genes) at single base-pair resolution. We find that 64% of nucleotide positions are invariant, and variant positions vary in a median of just 0.6% of strains. Additionally, non-coding alleles are sufficient to recover E. coli phylogroups. We find that core promoter elements and transcription factor binding sites are significantly conserved, especially those located upstream of essential or highly-expressed genes. However, variability in conservation of transcription factor binding sites is significant both within and across regulons. Finally, we contrast mutations acquired during adaptive laboratory evolution with wild-type variation, finding that the former preferentially alter positions that the latter conserves. Overall, this analysis elucidates the wealth of information found in E. coli non-coding sequence variation and expands pangenomic studies to non-coding regulatory regions at single-nucleotide resolution.
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Affiliation(s)
- Cameron R Lamoureux
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Patrick V Phaneuf
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Bernhard O Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Daniel C Zielinski
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
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2
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Yu L, Gao Y, He Y, Liu Y, Shen J, Liang H, Gong R, Duan H, Price NPJ, Song X, Deng Z, Chen W. Developing the E. coli platform for efficient production of UMP-derived chemicals. Metab Eng 2024; 83:61-74. [PMID: 38522576 DOI: 10.1016/j.ymben.2024.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 03/10/2024] [Accepted: 03/21/2024] [Indexed: 03/26/2024]
Abstract
5-Methyluridine (5-MU) is a prominent intermediate for industrial synthesis of several antiviral-drugs, however, its availability over the past decades has overwhelmingly relied on chemical and enzymatic strategies. Here, we have realized efficient production of 5-MU in E. coli, for the first time, via a designer artificial pathway consisting of a two-enzyme cascade (UMP 5-methylase and phosphatase). More importantly, we have engineered the E. coli cell factory to boost 5-MU production by systematic evaluation of multiple strategies, and as a proof of concept, we have further developed an antibiotic-free fermentation strategy to realize 5-MU production (10.71 g/L) in E. coli MB229 (a ΔthyA strain). Remarkably, we have also established a versatile and robust platform with exploitation of the engineered E. coli for efficient production of diversified UMP-derived chemicals. This study paves the way for future engineering of E. coli as a synthetic biology platform for acceleratively accessing UMP-derived chemical diversities.
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Affiliation(s)
- Le Yu
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Yaojie Gao
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Yuanyuan He
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Yang Liu
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Jianning Shen
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Han Liang
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Rong Gong
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - He Duan
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Neil P J Price
- US Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, Peoria, IL, USA
| | - Xuemin Song
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Zixin Deng
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; TaiKang Center for Life and Medical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Wenqing Chen
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China; TaiKang Center for Life and Medical Sciences, Wuhan University, Wuhan, 430071, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China.
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3
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Deal C, De Wannemaeker L, De Mey M. Towards a rational approach to promoter engineering: understanding the complexity of transcription initiation in prokaryotes. FEMS Microbiol Rev 2024; 48:fuae004. [PMID: 38383636 PMCID: PMC10911233 DOI: 10.1093/femsre/fuae004] [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: 08/31/2023] [Revised: 01/29/2024] [Accepted: 02/20/2024] [Indexed: 02/23/2024] Open
Abstract
Promoter sequences are important genetic control elements. Through their interaction with RNA polymerase they determine transcription strength and specificity, thereby regulating the first step in gene expression. Consequently, they can be targeted as elements to control predictability and tuneability of a genetic circuit, which is essential in applications such as the development of robust microbial cell factories. This review considers the promoter elements implicated in the three stages of transcription initiation, detailing the complex interplay of sequence-specific interactions that are involved, and highlighting that DNA sequence features beyond the core promoter elements work in a combinatorial manner to determine transcriptional strength. In particular, we emphasize that, aside from promoter recognition, transcription initiation is also defined by the kinetics of open complex formation and promoter escape, which are also known to be highly sequence specific. Significantly, we focus on how insights into these interactions can be manipulated to lay the foundation for a more rational approach to promoter engineering.
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Affiliation(s)
- Cara Deal
- Centre for Synthetic Biology, Ghent University. Coupure Links 653, BE-9000 Ghent, Belgium
| | - Lien De Wannemaeker
- Centre for Synthetic Biology, Ghent University. Coupure Links 653, BE-9000 Ghent, Belgium
| | - Marjan De Mey
- Centre for Synthetic Biology, Ghent University. Coupure Links 653, BE-9000 Ghent, Belgium
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4
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Picker MA, Karney MMA, Gerson TM, Karabachev A, Duhart J, McKenna J, Wing H. Localized modulation of DNA supercoiling, triggered by the Shigella anti-silencer VirB, is sufficient to relieve H-NS-mediated silencing. Nucleic Acids Res 2023; 51:3679-3695. [PMID: 36794722 PMCID: PMC10164555 DOI: 10.1093/nar/gkad088] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 01/27/2023] [Accepted: 01/31/2023] [Indexed: 02/17/2023] Open
Abstract
In Bacteria, nucleoid structuring proteins govern nucleoid dynamics and regulate transcription. In Shigella spp., at ≤30°C, the histone-like nucleoid structuring protein (H-NS) transcriptionally silences many genes on the large virulence plasmid. Upon a switch to 37°C, VirB, a DNA binding protein and key transcriptional regulator of Shigella virulence, is produced. VirB functions to counter H-NS-mediated silencing in a process called transcriptional anti-silencing. Here, we show that VirB mediates a loss of negative DNA supercoils from our plasmid-borne, VirB-regulated PicsP-lacZ reporter in vivo. The changes are not caused by a VirB-dependent increase in transcription, nor do they require the presence of H-NS. Instead, the VirB-dependent change in DNA supercoiling requires the interaction of VirB with its DNA binding site, a critical first step in VirB-dependent gene regulation. Using two complementary approaches, we show that VirB:DNA interactions in vitro introduce positive supercoils in plasmid DNA. Subsequently, by exploiting transcription-coupled DNA supercoiling, we reveal that a localized loss of negative supercoils is sufficient to alleviate H-NS-mediated transcriptional silencing independently of VirB. Together, our findings provide novel insight into VirB, a central regulator of Shigella virulence and, more broadly, a molecular mechanism that offsets H-NS-dependent silencing of transcription in bacteria.
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Affiliation(s)
- Michael A Picker
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Monika M A Karney
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Taylor M Gerson
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | | | - Juan C Duhart
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Joy A McKenna
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Helen J Wing
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
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5
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Nayarisseri A, Bhrdwaj A, Khan A, Sharma K, Shaheen U, Selvaraj C, Khan MA, Abhirami R, Pravin MA, Shri GR, Raje D, Singh SK. Promoter–motif extraction from co-regulated genes and their relevance to co-expression using E. coli as a model. Brief Funct Genomics 2023; 22:204-216. [PMID: 37053503 DOI: 10.1093/bfgp/elac043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/29/2022] [Accepted: 10/26/2022] [Indexed: 02/04/2023] Open
Abstract
Abstract
Gene expression varies due to the intrinsic stochasticity of transcription or as a reaction to external perturbations that generate cellular mutations. Co-regulation, co-expression and functional similarity of substances have been employed for indoctrinating the process of the transcriptional paradigm. The difficult process of analysing complicated proteomes and biological switches has been made easier by technical improvements, and microarray technology has flourished as a viable platform. Therefore, this research enables Microarray to cluster genes that are co-expressed and co-regulated into specific segments. Copious search algorithms have been employed to ascertain diacritic motifs or a combination of motifs that are performing regular expression, and their relevant information corresponding to the gene patterns is also documented. The associated genes co-expression and relevant cis-elements are further explored by engaging Escherichia coli as a model organism. Various clustering algorithms have also been used to generate classes of genes with similar expression profiles. A promoter database ‘EcoPromDB’ has been developed by referring RegulonDB database; this promoter database is freely available at www.ecopromdb.eminentbio.com and is divided into two sub-groups, depending upon the results of co-expression and co-regulation analyses.
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Affiliation(s)
- Anuraj Nayarisseri
- Eminent Biosciences In silico Research Laboratory, , 91, Sector-A, Mahalakshmi Nagar, Indore, 452010, Madhya Pradesh , India
- LeGene Biosciences Pvt Ltd Bioinformatics Research Laboratory, , 91, Sector-A, Mahalakshmi Nagar, Indore, 452010, Madhya Pradesh , India
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
| | - Anushka Bhrdwaj
- Eminent Biosciences In silico Research Laboratory, , 91, Sector-A, Mahalakshmi Nagar, Indore, 452010, Madhya Pradesh , India
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
| | - Arshiya Khan
- Eminent Biosciences In silico Research Laboratory, , 91, Sector-A, Mahalakshmi Nagar, Indore, 452010, Madhya Pradesh , India
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
| | - Khushboo Sharma
- Eminent Biosciences In silico Research Laboratory, , 91, Sector-A, Mahalakshmi Nagar, Indore, 452010, Madhya Pradesh , India
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
| | - Uzma Shaheen
- Eminent Biosciences In silico Research Laboratory, , 91, Sector-A, Mahalakshmi Nagar, Indore, 452010, Madhya Pradesh , India
| | - Chandrabose Selvaraj
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
| | - Mohammad Aqueel Khan
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
| | - Rajaram Abhirami
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
| | - Muthuraja Arun Pravin
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
| | - Gurunathan Rubha Shri
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
| | - Dhanjay Raje
- Eminent Biosciences In silico Research Laboratory, , 91, Sector-A, Mahalakshmi Nagar, Indore, 452010, Madhya Pradesh , India
| | - Sanjeev Kumar Singh
- Alagappa University Computer Aided Drug Designing and Molecular Modeling Lab, Department of Bioinformatics, , Karaikudi, 630003, Tamil Nadu , India
- Department of Data Sciences, Centre of Biomedical Research , SGPGIMS Campus, Raebareli Rd, Lucknow 226014, India
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6
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Selim AS, Perry JM, Nasr MA, Pimprikar JM, Shih SCC. A Synthetic Biosensor for Detecting Putrescine in Beef Samples. ACS APPLIED BIO MATERIALS 2022; 5:5487-5496. [PMID: 36356104 DOI: 10.1021/acsabm.2c00824] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Biogenic amines (BAs) are toxicological risks present in many food products. Putrescine is the most common foodborne BA and is frequently used as a quality control marker. Currently, there is a lack of regulation concerning safe putrescine limits in food as well as outdated food handling practices leading to unnecessary putrescine intake. Conventional methods used to evaluate BAs in food are generally time-consuming and resource-heavy with few options for on-site analysis. In response to this challenge, we have developed a transcription factor-based biosensor for the quantification of putrescine in beef samples. In this work, we use a naturally occurring putrescine responsive repressor-operator pair (PuuR-puuO) native to Escherichia coli. Moreover, we demonstrate the use of the cell-free putrescine biosensor on a paper-based device that enables rapid low-cost detection of putrescine in beef samples stored at different temperatures. The results presented demonstrate the potential role of using paper-based biosensors for on-site testing, particularly as an index for determining meat product stability and quality.
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Affiliation(s)
- Alaa S Selim
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, QuébecH4B 1R6, Canada.,Centre for Applied Synthetic Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, QuébecH4B 1R6, Canada
| | - James M Perry
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, QuébecH4B 1R6, Canada.,Centre for Applied Synthetic Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, QuébecH4B 1R6, Canada
| | - Mohamed A Nasr
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, QuébecH4B 1R6, Canada.,Centre for Applied Synthetic Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, QuébecH4B 1R6, Canada
| | - Jay M Pimprikar
- Centre for Applied Synthetic Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, QuébecH4B 1R6, Canada.,Department of Electrical and Computer Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montréal, QuébecH3G 1M8, Canada
| | - Steve C C Shih
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, QuébecH4B 1R6, Canada.,Centre for Applied Synthetic Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, QuébecH4B 1R6, Canada.,Department of Electrical and Computer Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montréal, QuébecH3G 1M8, Canada
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7
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Regulation of the icl1 Gene Encoding the Major Isocitrate Lyase in Mycobacterium smegmatis. J Bacteriol 2021; 203:e0040221. [PMID: 34516281 DOI: 10.1128/jb.00402-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacterium smegmatis has two isocitrate lyase (ICL) isozymes (MSMEG_0911 and MSMEG_3706). We demonstrated that ICL1 (MSMEG_0911) is the predominantly expressed ICL in M. smegmatis and plays a major role in growth on acetate or fatty acid as the sole carbon and energy source. Expression of the icl1 gene in M. smegmatis was demonstrated to be strongly upregulated during growth on acetate relative to that in M. smegmatis grown on glucose. Expression of icl1 was shown to be positively regulated by the RamB activator, and three RamB-binding sites (RamBS1, RamBS2, and RamBS3) were identified in the upstream region of icl1 using DNase I footprinting analysis. Succinyl coenzyme A (succinyl-CoA) was shown to increase the affinity of binding of RamB to its binding sites and enable RamB to bind to RamBS2, which is the most important site for RamB-mediated induction of icl1 expression. These results suggest that succinyl-CoA serves as a coinducer molecule for RamB. Our study also showed that cAMP receptor protein (Crp1; MSMEG_6189) represses icl1 expression in M. smegmatis grown in the presence of glucose. Therefore, the strong induction of icl1 expression during growth on acetate as the sole carbon source relative to the weak expression of icl1 during growth on glucose is likely to result from combined effects of RamB-mediated induction of icl1 in the presence of acetate and Crp-mediated repression of icl1 in the presence of glucose. IMPORTANCE Carbon flux through the glyoxylate shunt has been suggested to affect virulence, persistence, and antibiotic resistance of Mycobacterium tuberculosis. Therefore, it is important to understand the precise mechanism underlying the regulation of the icl gene encoding the key enzyme of the glyoxylate shunt. Using Mycobacterium smegmatis, this study revealed the regulation mechanism underlying induction of icl1 expression in M. smegmatis when the glyoxylate shunt is required. The conservation of the cis- and trans-acting regulatory elements related to icl1 regulation in both M. smegmatis and M. tuberculosis implies that a similar regulatory mechanism operates for the regulation of icl1 expression in M. tuberculosis.
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8
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Zou Y, Li C, Zhang R, Jiang T, Liu N, Wang J, Wang X, Yan Y. Exploring the Tunability and Dynamic Properties of MarR-PmarO Sensor System in Escherichia coli. ACS Synth Biol 2021; 10:2076-2086. [PMID: 34319697 DOI: 10.1021/acssynbio.1c00245] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Transcriptional factor-based biosensors (TFBs) have been widely used in dynamic pathway control or high-throughput screening. Here, we systematically explored the tunability of a salicylic acid responsive regulator MarR from Escherichia coli aiming to explore its engineering potential. The effect of endogenous MarR in E. coli on the MarR-PmarO biosensor system was investigated. Furthermore, to investigate the function of marO binding boxes in this biosensor system, a series of hybrid promoters were constructed by placing the marO binding boxes in the strong constitutive pL promoter. The engineered hybrid promoters became responsive to MarR and salicylic acid. To further study the influence of each nucleotide in the marO box on MarR binding, we employed dynamic modeling to simulate the interaction and binding energy between each nucleotide in the marO boxes with the corresponding residues on MarR. Guided by the results of the simulation, we introduced mutations to key positions on the hybrid promoters and investigated corresponding dynamic performance. Two promoter variants I12AII4T and I12AII14T that exhibited improved responsive strengths and shifted dynamic ranges were obtained, which can be beneficial for future metabolic engineering research.
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Affiliation(s)
- Yusong Zou
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, Georgia 30602, United States
| | - Chenyi Li
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, Georgia 30602, United States
| | - Ruihua Zhang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, Georgia 30602, United States
| | - Tian Jiang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, Georgia 30602, United States
| | - Ning Liu
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, College of Engineering, The University of Georgia, Athens, Georgia 30602, United States
| | - Jian Wang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, Georgia 30602, United States
| | - Xianqiao Wang
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, College of Engineering, The University of Georgia, Athens, Georgia 30602, United States
| | - Yajun Yan
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, Georgia 30602, United States
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9
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Abstract
Metabolic engineering reprograms cells to synthesize value-added products. In doing so, endogenous genes are altered and heterologous genes can be introduced to achieve the necessary enzymatic reactions. Dynamic regulation of metabolic flux is a powerful control scheme to alleviate and overcome the competing cellular objectives that arise from the introduction of these production pathways. This review explores dynamic regulation strategies that have demonstrated significant production benefits by targeting the metabolic node corresponding to a specific challenge. We summarize the stimulus-responsive control circuits employed in these strategies that determine the criterion for actuating a dynamic response and then examine the points of control that couple the stimulus-responsive circuit to a shift in metabolic flux.
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Affiliation(s)
- Cynthia Ni
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
| | - Christina V Dinh
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
| | - Kristala L J Prather
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
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10
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Kędzierska B, Potrykus K, Szalewska-Pałasz A, Wodzikowska B. Insights into Transcriptional Repression of the Homologous Toxin-Antitoxin Cassettes yefM-yoeB and axe-txe. Int J Mol Sci 2020; 21:ijms21239062. [PMID: 33260607 PMCID: PMC7730913 DOI: 10.3390/ijms21239062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 11/16/2022] Open
Abstract
Transcriptional repression is a mechanism which enables effective gene expression switch off. The activity of most of type II toxin-antitoxin (TA) cassettes is controlled in this way. These cassettes undergo negative autoregulation by the TA protein complex which binds to the promoter/operator sequence and blocks transcription initiation of the TA operon. Precise and tight control of this process is vital to avoid uncontrolled expression of the toxin component. Here, we employed a series of in vivo and in vitro experiments to establish the molecular basis for previously observed differences in transcriptional activity and repression levels of the pyy and pat promoters which control expression of two homologous TA systems, YefM-YoeB and Axe-Txe, respectively. Transcriptional fusions of promoters with a lux reporter, together with in vitro transcription, EMSA and footprinting assays revealed that: (1) the different sequence composition of the -35 promoter element is responsible for substantial divergence in strengths of the promoters; (2) variations in repression result from the TA repressor complex acting at different steps in the transcription initiation process; (3) transcription from an additional promoter upstream of pat also contributes to the observed inefficient repression of axe-txe module. This study provides evidence that even closely related TA cassettes with high sequence similarity in the promoter/operator region may employ diverse mechanisms for transcriptional regulation of their genes.
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11
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Mejía-Almonte C, Busby SJW, Wade JT, van Helden J, Arkin AP, Stormo GD, Eilbeck K, Palsson BO, Galagan JE, Collado-Vides J. Redefining fundamental concepts of transcription initiation in bacteria. Nat Rev Genet 2020; 21:699-714. [PMID: 32665585 PMCID: PMC7990032 DOI: 10.1038/s41576-020-0254-8] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2020] [Indexed: 12/15/2022]
Abstract
Despite enormous progress in understanding the fundamentals of bacterial gene regulation, our knowledge remains limited when compared with the number of bacterial genomes and regulatory systems to be discovered. Derived from a small number of initial studies, classic definitions for concepts of gene regulation have evolved as the number of characterized promoters has increased. Together with discoveries made using new technologies, this knowledge has led to revised generalizations and principles. In this Expert Recommendation, we suggest precise, updated definitions that support a logical, consistent conceptual framework of bacterial gene regulation, focusing on transcription initiation. The resulting concepts can be formalized by ontologies for computational modelling, laying the foundation for improved bioinformatics tools, knowledge-based resources and scientific communication. Thus, this work will help researchers construct better predictive models, with different formalisms, that will be useful in engineering, synthetic biology, microbiology and genetics.
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Affiliation(s)
- Citlalli Mejía-Almonte
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Morelos, Cuernavaca, México
| | | | - Joseph T Wade
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Jacques van Helden
- Aix-Marseille University, INSERM UMR S 1090, Theory and Approaches of Genome Complexity (TAGC), Marseille, France
- CNRS, Institut Français de Bioinformatique, IFB-core, UMS 3601, Evry, France
| | - Adam P Arkin
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA
| | - Gary D Stormo
- Department of Genetics, Washington University School of Medicine, St Louis, MO, USA
| | - Karen Eilbeck
- Department of Biomedical Informatics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Bernhard O Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - James E Galagan
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Julio Collado-Vides
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Morelos, Cuernavaca, México.
- Department of Biomedical Engineering, Boston University, Boston, MA, USA.
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12
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Determination and Dissection of DNA-Binding Specificity for the Thermus thermophilus HB8 Transcriptional Regulator TTHB099. Int J Mol Sci 2020; 21:ijms21217929. [PMID: 33114549 PMCID: PMC7662524 DOI: 10.3390/ijms21217929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 10/22/2020] [Accepted: 10/24/2020] [Indexed: 01/26/2023] Open
Abstract
Transcription factors (TFs) have been extensively researched in certain well-studied organisms, but far less so in others. Following the whole-genome sequencing of a new organism, TFs are typically identified through their homology with related proteins in other organisms. However, recent findings demonstrate that structurally similar TFs from distantly related bacteria are not usually evolutionary orthologs. Here we explore TTHB099, a cAMP receptor protein (CRP)-family TF from the extremophile Thermus thermophilus HB8. Using the in vitro iterative selection method Restriction Endonuclease Protection, Selection and Amplification (REPSA), we identified the preferred DNA-binding motif for TTHB099, 5′–TGT(A/g)NBSYRSVN(T/c)ACA–3′, and mapped potential binding sites and regulated genes within the T. thermophilus HB8 genome. Comparisons with expression profile data in TTHB099-deficient and wild type strains suggested that, unlike E. coli CRP (CRPEc), TTHB099 does not have a simple regulatory mechanism. However, we hypothesize that TTHB099 can be a dual-regulator similar to CRPEc.
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13
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Monteiro LMO, Sanches-Medeiros A, Westmann CA, Silva-Rocha R. Unraveling the Complex Interplay of Fis and IHF Through Synthetic Promoter Engineering. Front Bioeng Biotechnol 2020; 8:510. [PMID: 32626694 PMCID: PMC7314903 DOI: 10.3389/fbioe.2020.00510] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 04/30/2020] [Indexed: 02/03/2023] Open
Abstract
Bacterial promoters are usually formed by multiple cis-regulatory elements recognized by a plethora of transcriptional factors (TFs). From those, global regulators are key elements since these TFs are responsible for the regulation of hundreds of genes in the bacterial genome. For instance, Fis and IHF are global regulators that play a major role in gene expression control in Escherichia coli, and usually, multiple cis-regulatory elements for these proteins are present at target promoters. Here, we investigated the relationship between the architecture of the cis-regulatory elements for Fis and IHF in E. coli. For this, we analyze 42 synthetic promoter variants harboring consensus cis-elements for Fis and IHF at different distances from the core -35/-10 region and in various numbers and combinations. We first demonstrated that although Fis preferentially recognizes its consensus cis-element, it can also recognize, to some extent, the consensus-binding site for IHF, and the same was true for IHF, which was also able to recognize Fis binding sites. However, changing the arrangement of the cis-elements (i.e., the position or number of sites) can completely abolish the non-specific binding of both TFs. More remarkably, we demonstrated that combining cis-elements for both TFs could result in Fis and IHF repressed or activated promoters depending on the final architecture of the promoters in an unpredictable way. Taken together, the data presented here demonstrate how small changes in the architecture of bacterial promoters could result in drastic changes in the final regulatory logic of the system, with important implications for the understanding of natural complex promoters in bacteria and their engineering for novel applications.
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Affiliation(s)
| | | | - Cauã Antunes Westmann
- Ribeirão Preto Medical School (FMRP), University of São Paulo, Ribeirão Preto, Brazil
| | - Rafael Silva-Rocha
- Ribeirão Preto Medical School (FMRP), University of São Paulo, Ribeirão Preto, Brazil
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14
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The Antiactivator of Type III Secretion, OspD1, Is Transcriptionally Regulated by VirB and H-NS from Remote Sequences in Shigella flexneri. J Bacteriol 2020; 202:JB.00072-20. [PMID: 32123035 DOI: 10.1128/jb.00072-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 02/24/2020] [Indexed: 01/08/2023] Open
Abstract
Shigella species, the causal agents of bacillary dysentery, use a type III secretion system (T3SS) to inject two waves of virulence proteins, known as effectors, into the colonic epithelium to subvert host cell machinery. Prior to host cell contact and secretion of the first wave of T3SS effectors, OspD1, an effector and antiactivator protein, prevents premature production of the second wave of effectors. Despite this important role, regulation of the ospD1 gene is not well understood. While ospD1 belongs to the large regulon of VirB, a transcriptional antisilencing protein that counters silencing mediated by the histone-like nucleoid structuring protein H-NS, it remains unclear if VirB directly or indirectly regulates ospD1 Additionally, it is not known if ospD1 is regulated by H-NS. Here, we identify the primary ospD1 transcription start site (+1) and show that the ospD1 promoter is remotely regulated by both VirB and H-NS. Our findings demonstrate that VirB regulation of ospD1 requires at least one of the two newly identified VirB regulatory sites, centered at -978 and -1270 relative to the ospD1 +1. Intriguingly, one of these sites lies on a 193-bp sequence found in three conserved locations on the large virulence plasmids of Shigella The region required for H-NS-dependent silencing of ospD1 lies between -1120 and -820 relative to the ospD1 +1. Thus, our study provides further evidence that cis-acting regulatory sequences for transcriptional antisilencers and silencers, such as VirB and H-NS, can lie far upstream of the canonical bacterial promoter region (i.e., -250 to +1).IMPORTANCE Transcriptional silencing and antisilencing mechanisms regulate virulence gene expression in many important bacterial pathogens. In Shigella species, plasmid-borne virulence genes, such as those encoding the type III secretion system (T3SS), are silenced by the histone-like nucleoid structuring protein H-NS and antisilenced by VirB. Previous work at the plasmid-borne icsP locus revealed that VirB binds to a remotely located cis-acting regulatory site to relieve transcriptional silencing mediated by H-NS. Here, we characterize a second example of remote VirB antisilencing at ospD1, which encodes a T3SS antiactivator and effector. Our study highlights that remote transcriptional silencing and antisilencing occur more frequently in Shigella than previously thought, and it raises the possibility that long-range transcriptional regulation in bacteria is commonplace.
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15
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Salgado H, Martínez-Flores I, Bustamante VH, Alquicira-Hernández K, García-Sotelo JS, García-Alonso D, Collado-Vides J. Using RegulonDB, the Escherichia coli K-12 Gene Regulatory Transcriptional Network Database. ACTA ACUST UNITED AC 2019; 61:1.32.1-1.32.30. [PMID: 30040192 DOI: 10.1002/cpbi.43] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In RegulonDB, for over 25 years, we have been gathering knowledge by manual curation from original scientific literature on the regulation of transcription initiation and genome organization in transcription units of the Escherichia coli K-12 genome. This unit describes six basic protocols that can serve as a guiding introduction to the main content of the current version (v9.4) of this electronic resource. These protocols include general navigation as well as searching for specific objects such as genes, gene products, transcription units, promoters, transcription factors, coexpression, and genetic sensory response units or GENSOR Units. In these protocols, the user will find an initial introduction to the concepts pertinent to the protocol, the content obtained when performing the given navigation, and the necessary resources for carrying out the protocol. This easy-to-follow presentation should help anyone interested in quickly seeing all that is currently offered in RegulonDB, including position weight matrices of transcription factors, coexpression values based on published microarrays, and the GENSOR Units unique to RegulonDB that offer regulatory mechanisms in the context of their signals and metabolic consequences. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Heladia Salgado
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Irma Martínez-Flores
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Víctor H Bustamante
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Kevin Alquicira-Hernández
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Jair S García-Sotelo
- Laboratorio Internacional de Investigación sobre el Genoma Humano, Universidad Nacional Autónoma de México, Santiago de Querétaro, Querétaro, México
| | - Delfino García-Alonso
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Julio Collado-Vides
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
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16
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Abstract
Proteus mirabilis, a Gram-negative rod-shaped bacterium most noted for its swarming motility and urease activity, frequently causes catheter-associated urinary tract infections (CAUTIs) that are often polymicrobial. These infections may be accompanied by urolithiasis, the development of bladder or kidney stones due to alkalinization of urine from urease-catalyzed urea hydrolysis. Adherence of the bacterium to epithelial and catheter surfaces is mediated by 17 different fimbriae, most notably MR/P fimbriae. Repressors of motility are often encoded by these fimbrial operons. Motility is mediated by flagella encoded on a single contiguous 54-kb chromosomal sequence. On agar plates, P. mirabilis undergoes a morphological conversion to a filamentous swarmer cell expressing hundreds of flagella. When swarms from different strains meet, a line of demarcation, a "Dienes line," develops due to the killing action of each strain's type VI secretion system. During infection, histological damage is caused by cytotoxins including hemolysin and a variety of proteases, some autotransported. The pathogenesis of infection, including assessment of individual genes or global screens for virulence or fitness factors has been assessed in murine models of ascending urinary tract infections or CAUTIs using both single-species and polymicrobial models. Global gene expression studies performed in culture and in the murine model have revealed the unique metabolism of this bacterium. Vaccines, using MR/P fimbria and its adhesin, MrpH, have been shown to be efficacious in the murine model. A comprehensive review of factors associated with urinary tract infection is presented, encompassing both historical perspectives and current advances.
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Wang T, Zhao X, Shi H, Sun L, Li Y, Li Q, Zhang H, Chen S, Li J. Positive and negative regulation of transferred nif genes mediated by indigenous GlnR in Gram-positive Paenibacillus polymyxa. PLoS Genet 2018; 14:e1007629. [PMID: 30265664 PMCID: PMC6191146 DOI: 10.1371/journal.pgen.1007629] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 10/16/2018] [Accepted: 08/14/2018] [Indexed: 12/29/2022] Open
Abstract
Ammonia is a major signal that regulates nitrogen fixation in most diazotrophs. Regulation of nitrogen fixation by ammonia in the Gram-negative diazotrophs is well-characterized. In these bacteria, this regulation occurs mainly at the level of nif (nitrogen fixation) gene transcription, which requires a nif-specific activator, NifA. Although Gram-positive and diazotrophic Paenibacilli have been extensively used as a bacterial fertilizer in agriculture, how nitrogen fixation is regulated in response to nitrogen availability in these bacteria remains unclear. An indigenous GlnR and GlnR/TnrA-binding sites in the promoter region of the nif cluster are conserved in these strains, indicating the role of GlnR as a regulator of nitrogen fixation. In this study, we for the first time reveal that GlnR of Paenibacillus polymyxa WLY78 is essentially required for nif gene transcription under nitrogen limitation, whereas both GlnR and glutamine synthetase (GS) encoded by glnA within glnRA operon are required for repressing nif expression under excess nitrogen. Dimerization of GlnR is necessary for binding of GlnR to DNA. GlnR in P. polymyxa WLY78 exists in a mixture of dimers and monomers. The C-terminal region of GlnR monomer is an autoinhibitory domain that prevents GlnR from binding DNA. Two GlnR-biding sites flank the -35/-10 regions of the nif promoter of the nif operon (nifBHDKENXhesAnifV). The GlnR-binding site Ⅰ (located upstream of -35/-10 regions of the nif promoter) is specially required for activating nif transcription, while GlnR-binding siteⅡ (located downstream of -35/-10 regions of the nif promoter) is for repressing nif expression. Under nitrogen limitation, GlnR dimer binds to GlnR-binding siteⅠ in a weak and transient association way and then activates nif transcription. During excess nitrogen, glutamine binds to and feedback inhibits GS by forming the complex FBI-GS. The FBI-GS interacts with the C-terminal domain of GlnR and stabilizes the binding affinity of GlnR to GlnR-binding site Ⅱ and thus represses nif transcription. GlnR is a global transcription regulator of nitrogen metabolism in Bacillus and other Gram-positive bacteria. GlnR generally functions as repressor and inhibits gene transcription under excess nitrogen. Our study for the first time reveals that GlnR simultaneously acted as an activator and a repressor for nitrogen fixation of Paenibacillus by binding to different loci of the single nif promoter region according to nitrogen availability. In excess glutamine, the feedback inhibited form of glutamine synthetase (GS) encoded by glnA within glnRA operon directly interacts with the C-terminal domain of GlnR and then controls the GlnR activity. Also, overexpression of glnR or deletion of glnA or mutagenesis of GlnR-binding site Ⅱ led to constitutive nif expression in the absence or presence of high (100 mM) concentration of ammonia. This work represents the first instance of a dual positive and negative regulatory mechanism of nitrogen fixation.
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Affiliation(s)
- Tianshu Wang
- State Key Laboratory for Agrobiotechnology, Key Laboratory of Soil Microbiology of Agriculture Ministry and College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Xiyun Zhao
- State Key Laboratory for Agrobiotechnology, Key Laboratory of Soil Microbiology of Agriculture Ministry and College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Haowen Shi
- State Key Laboratory for Agrobiotechnology, Key Laboratory of Soil Microbiology of Agriculture Ministry and College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Li Sun
- State Key Laboratory for Agrobiotechnology, Key Laboratory of Soil Microbiology of Agriculture Ministry and College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Yongbin Li
- State Key Laboratory for Agrobiotechnology, Key Laboratory of Soil Microbiology of Agriculture Ministry and College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Qin Li
- State Key Laboratory for Agrobiotechnology, Key Laboratory of Soil Microbiology of Agriculture Ministry and College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Haowei Zhang
- State Key Laboratory for Agrobiotechnology, Key Laboratory of Soil Microbiology of Agriculture Ministry and College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Sanfeng Chen
- State Key Laboratory for Agrobiotechnology, Key Laboratory of Soil Microbiology of Agriculture Ministry and College of Biological Sciences, China Agricultural University, Beijing, P. R. China
- * E-mail:
| | - Jilun Li
- State Key Laboratory for Agrobiotechnology, Key Laboratory of Soil Microbiology of Agriculture Ministry and College of Biological Sciences, China Agricultural University, Beijing, P. R. China
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18
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Santos-Zavaleta A, Sánchez-Pérez M, Salgado H, Velázquez-Ramírez DA, Gama-Castro S, Tierrafría VH, Busby SJW, Aquino P, Fang X, Palsson BO, Galagan JE, Collado-Vides J. A unified resource for transcriptional regulation in Escherichia coli K-12 incorporating high-throughput-generated binding data into RegulonDB version 10.0. BMC Biol 2018; 16:91. [PMID: 30115066 PMCID: PMC6094552 DOI: 10.1186/s12915-018-0555-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 07/25/2018] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Our understanding of the regulation of gene expression has benefited from the availability of high-throughput technologies that interrogate the whole genome for the binding of specific transcription factors and gene expression profiles. In the case of widely used model organisms, such as Escherichia coli K-12, the new knowledge gained from these approaches needs to be integrated with the legacy of accumulated knowledge from genetic and molecular biology experiments conducted in the pre-genomic era in order to attain the deepest level of understanding possible based on the available data. RESULTS In this paper, we describe an expansion of RegulonDB, the database containing the rich legacy of decades of classic molecular biology experiments supporting what we know about gene regulation and operon organization in E. coli K-12, to include the genome-wide dataset collections from 32 ChIP and 19 gSELEX publications, in addition to around 60 genome-wide expression profiles relevant to the functional significance of these datasets and used in their curation. Three essential features for the integration of this information coming from different methodological approaches are: first, a controlled vocabulary within an ontology for precisely defining growth conditions; second, the criteria to separate elements with enough evidence to consider them involved in gene regulation from isolated transcription factor binding sites without such support; and third, an expanded computational model supporting this knowledge. Altogether, this constitutes the basis for adequately gathering and enabling the comparisons and integration needed to manage and access such wealth of knowledge. CONCLUSIONS This version 10.0 of RegulonDB is a first step toward what should become the unifying access point for current and future knowledge on gene regulation in E. coli K-12. Furthermore, this model platform and associated methodologies and criteria can be emulated for gathering knowledge on other microbial organisms.
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Affiliation(s)
- Alberto Santos-Zavaleta
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos México
| | - Mishael Sánchez-Pérez
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos México
| | - Heladia Salgado
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos México
| | | | - Socorro Gama-Castro
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos México
| | - Víctor H. Tierrafría
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos México
| | | | - Patricia Aquino
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts USA
| | - Xin Fang
- Department of Bioengineering, University of California San Diego, La Jolla, California USA
| | - Bernhard O. Palsson
- Department of Bioengineering, University of California San Diego, La Jolla, California USA
- Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark
| | - James E. Galagan
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts USA
| | - Julio Collado-Vides
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos México
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts USA
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19
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Weatherspoon-Griffin N, Picker MA, Pew KL, Park HS, Ginete DR, Karney MMA, Usufzy P, Castellanos MI, Duhart JC, Harrison DJ, Socea JN, Karabachev AD, Hensley CT, Howerton AJ, Ojeda-Daulo R, Immak JA, Wing HJ. Insights into transcriptional silencing and anti-silencing in Shigella flexneri: a detailed molecular analysis of the icsP virulence locus. Mol Microbiol 2018; 108:505-518. [PMID: 29453862 PMCID: PMC6311345 DOI: 10.1111/mmi.13932] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2018] [Indexed: 11/28/2022]
Abstract
Transcriptional silencing and anti-silencing mechanisms modulate bacterial physiology and virulence in many human pathogens. In Shigella species, many virulence plasmid genes are silenced by the histone-like nucleoid structuring protein H-NS and anti-silenced by the virulence gene regulator VirB. Despite the key role that these regulatory proteins play in Shigella virulence, their mechanisms of transcriptional control remain poorly understood. Here, we characterize the regulatory elements and their relative spacing requirements needed for the transcriptional silencing and anti-silencing of icsP, a locus that requires remotely located regulatory elements for both types of transcriptional control. Our findings highlight the flexibility of the regulatory elements' positions with respect to each other, and yet, a molecular roadblock docked between the VirB binding site and the upstream H-NS binding region abolishes transcriptional anti-silencing by VirB, providing insight into transcriptional anti-silencing. Our study also raises the need to re-evaluate the currently proposed VirB binding site. Models of transcriptional silencing and anti-silencing at this genetic locus are presented, and the implications for understanding these regulatory mechanisms in bacteria are discussed.
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Affiliation(s)
| | | | - Krystle L. Pew
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Hiromichi S. Park
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Daren R. Ginete
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Monika MA. Karney
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Pashtana Usufzy
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Maria I. Castellanos
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Juan Carlos Duhart
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Dustin J. Harrison
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Jillian N. Socea
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | | | | | | | - Rosa Ojeda-Daulo
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Joy A. Immak
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Helen J. Wing
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
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20
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Novel Two-Component System of Streptococcus sanguinis Affecting Functions Associated with Viability in Saliva and Biofilm Formation. Infect Immun 2018; 86:IAI.00942-17. [PMID: 29339459 DOI: 10.1128/iai.00942-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 01/08/2018] [Indexed: 02/07/2023] Open
Abstract
Streptococcus sanguinis is a pioneer species of teeth and a common opportunistic pathogen of infective endocarditis. In this study, we identified a two-component system, S. sanguinis SptRS (SptRS Ss ), affecting S. sanguinis survival in saliva and biofilm formation. Isogenic mutants of sptRSs (SKsptR) and sptSSs (SKsptS) showed reduced cell counts in ex vivo assays of viability in saliva compared to those of parent strain SK36 and complemented mutants. Reduced counts of the mutants in saliva were associated with reduced growth rates in nutrient-poor medium (RPMI) and increased susceptibility to the deposition of C3b and the membrane attach complex (MAC) of the complement system, a defense component of saliva and serum. Conversely, sptRSs and sptSSs mutants showed increased biofilm formation associated with higher levels of production of H2O2 and extracellular DNA. Reverse transcription-quantitative PCR (RT-qPCR) comparisons of strains indicated a global role of SptRS Ss in repressing genes for H2O2 production (2.5- to 15-fold upregulation of spxB, spxR, vicR, tpk, and ackA in sptRSs and sptSSs mutants), biofilm formation, and/or evasion of host immunity (2.1- to 11.4-fold upregulation of srtA, pcsB, cwdP, iga, and nt5e). Compatible with the homology of SptR Ss with AraC-type regulators, duplicate to multiple conserved repeats were identified in 1,000-bp regulatory regions of downstream genes, suggesting that SptR Ss regulates transcription by DNA looping. Significant transcriptional changes in the regulatory genes vicR, spxR, comE, comX, and mecA in the sptRSs and sptSSs mutants further indicated that SptRS Ss is part of a regulatory network that coordinates cell wall homeostasis, H2O2 production, and competence. This study reveals that SptRS Ss is involved in the regulation of crucial functions for S. sanguinis persistence in the oral cavity.
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21
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Layered dynamic regulation for improving metabolic pathway productivity in Escherichia coli. Proc Natl Acad Sci U S A 2018; 115:2964-2969. [PMID: 29507236 DOI: 10.1073/pnas.1716920115] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Microbial production of value-added chemicals from biomass is a sustainable alternative to chemical synthesis. To improve product titer, yield, and selectivity, the pathways engineered into microbes must be optimized. One strategy for optimization is dynamic pathway regulation, which modulates expression of pathway-relevant enzymes over the course of fermentation. Metabolic engineers have used dynamic regulation to redirect endogenous flux toward product formation, balance the production and consumption rates of key intermediates, and suppress production of toxic intermediates until later in the fermentation. Most cases, however, have utilized a single strategy for dynamically regulating pathway fluxes. Here we layer two orthogonal, autonomous, and tunable dynamic regulation strategies to independently modulate expression of two different enzymes to improve production of D-glucaric acid from a heterologous pathway. The first strategy uses a previously described pathway-independent quorum sensing system to dynamically knock down glycolytic flux and redirect carbon into production of glucaric acid, thereby switching cells from "growth" to "production" mode. The second strategy, developed in this work, uses a biosensor for myo-inositol (MI), an intermediate in the glucaric acid production pathway, to induce expression of a downstream enzyme upon sufficient buildup of MI. The latter, pathway-dependent strategy leads to a 2.5-fold increase in titer when used in isolation and a fourfold increase when added to a strain employing the former, pathway-independent regulatory system. The dual-regulation strain produces nearly 2 g/L glucaric acid, representing the highest glucaric acid titer reported to date in Escherichia coli K-12 strains.
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22
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Monteiro LMO, Arruda LM, Silva-Rocha R. Emergent Properties in Complex Synthetic Bacterial Promoters. ACS Synth Biol 2018; 7:602-612. [PMID: 29091423 DOI: 10.1021/acssynbio.7b00344] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Regulation of gene expression in bacteria results from the interplay between hundreds of transcriptional factors (TFs) at target promoters. However, how the arrangement of binding sites for TFs generates the regulatory logic of promoters is not well-known. Here, we generated and fully characterized a library of synthetic complex promoters for the global regulators, CRP and IHF, in Escherichia coli, which are formed by a weak -35/-10 consensus sequence preceded by four combinatorial binding sites for these two TFs. Using this approach, we found that while cis-elements for CRP preferentially activate promoters when located immediately upstream of the promoter consensus, binding sites for IHF mainly function as "UP" elements and stimulate transcription in several different architectures in the absence of this protein. However, the combination of CRP- and IHF-binding sites resulted in emergent properties in these complex promoters, where the activity of combinatorial promoters cannot be predicted from the individual behavior of its components. Taken together, the results presented here add to the information on architecture-logic of complex promoters in bacteria.
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Affiliation(s)
- Lummy Maria Oliveira Monteiro
- Systems and Synthetic Biology Lab,
Ribeirao Preto Medical School, University of São Paulo, Ribeirão
Preto, São Paulo, Brazil
| | - Letícia Magalhães Arruda
- Systems and Synthetic Biology Lab,
Ribeirao Preto Medical School, University of São Paulo, Ribeirão
Preto, São Paulo, Brazil
| | - Rafael Silva-Rocha
- Systems and Synthetic Biology Lab,
Ribeirao Preto Medical School, University of São Paulo, Ribeirão
Preto, São Paulo, Brazil
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23
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Chen Y, Ho JML, Shis DL, Gupta C, Long J, Wagner DS, Ott W, Josić K, Bennett MR. Tuning the dynamic range of bacterial promoters regulated by ligand-inducible transcription factors. Nat Commun 2018; 9:64. [PMID: 29302024 PMCID: PMC5754348 DOI: 10.1038/s41467-017-02473-5] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 12/01/2017] [Indexed: 11/09/2022] Open
Abstract
One challenge for synthetic biologists is the predictable tuning of genetic circuit regulatory components to elicit desired outputs. Gene expression driven by ligand-inducible transcription factor systems must exhibit the correct ON and OFF characteristics: appropriate activation and leakiness in the presence and absence of inducer, respectively. However, the dynamic range of a promoter (i.e., absolute difference between ON and OFF states) is difficult to control. We report a method that tunes the dynamic range of ligand-inducible promoters to achieve desired ON and OFF characteristics. We build combinatorial sets of AraC-and LasR-regulated promoters containing -10 and -35 sites from synthetic and Escherichia coli promoters. Four sequence combinations with diverse dynamic ranges were chosen to build multi-input transcriptional logic gates regulated by two and three ligand-inducible transcription factors (LacI, TetR, AraC, XylS, RhlR, LasR, and LuxR). This work enables predictable control over the dynamic range of regulatory components.
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Affiliation(s)
- Ye Chen
- Department of Biosciences, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - Joanne M L Ho
- Department of Biosciences, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - David L Shis
- Department of Biosciences, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - Chinmaya Gupta
- Department of Mathematics, University of Houston, 4800 Calhoun Road, Houston, TX, 77204, USA
| | - James Long
- Department of Biosciences, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - Daniel S Wagner
- Department of Biosciences, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - William Ott
- Department of Mathematics, University of Houston, 4800 Calhoun Road, Houston, TX, 77204, USA
| | - Krešimir Josić
- Department of Biosciences, Rice University, 6100 Main Street, Houston, TX, 77005, USA. .,Department of Mathematics, University of Houston, 4800 Calhoun Road, Houston, TX, 77204, USA. .,Department of Biology and Biochemistry, University of Houston, 4800 Calhoun Road, Houston, TX, 77204, USA.
| | - Matthew R Bennett
- Department of Biosciences, Rice University, 6100 Main Street, Houston, TX, 77005, USA. .,Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
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24
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Schmitt G, Arndt F, Kahnt J, Heider J. Adaptations to a Loss-of-Function Mutation in the Betaproteobacterium Aromatoleum aromaticum: Recruitment of Alternative Enzymes for Anaerobic Phenylalanine Degradation. J Bacteriol 2017; 199:e00383-17. [PMID: 28784814 PMCID: PMC5637171 DOI: 10.1128/jb.00383-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 07/30/2017] [Indexed: 12/22/2022] Open
Abstract
Anaerobic phenylalanine (Phe) degradation in the betaproteobacterium Aromatoleum aromaticum involves transamination and decarboxylation to phenylacetaldehyde, followed by oxidation to phenylacetate. The latter reaction is catalyzed simultaneously by two enzymes, a highly specific phenylacetaldehyde dehydrogenase (PDH) and a rather unspecific tungsten-dependent aldehyde oxidoreductase (AOR). Attempting to establish increased synthesis of AOR, we constructed a mutant lacking the gene for PDH. This mutant still grew on phenylalanine, exhibiting increased AOR activities on medium containing tungstate. In the absence of tungstate, the mutant showed initially severe growth deficiency, but it resumed growth on Phe after longer incubation times. Moreover, the growth rates of the mutant increased during several reinoculation cycles on either tungstate-proficient or -deficient media, reaching the same values as recorded in wild-type strains. We confirmed AOR as the major alternative enzyme serving Phe degradation under tungstate-supplied conditions and identified and characterized the alternative NAD-dependent aldehyde dehydrogenase AldB taking over the function under tungstate-deficient conditions. Sequence analysis of the respective genes from adapted cultures under either growth condition revealed a mutation in the upstream region of the aor operon and a mutation within the coding region of aldB, which are likely involved in the observed adaptation of the deletion mutant to regain fast growth on Phe.IMPORTANCE The betaproteobacterium Aromatoleum aromaticum degrades many aromatic compounds under denitrifying conditions. One of the steps of phenylalanine degradation is catalyzed by two simultaneously induced enzymes, a NAD(P)-dependent phenylacetaldehyde dehydrogenase and a W-containing aldehyde oxidoreductase. We report here that the latter fully complements a constructed deletion mutant lacking the gene for phenylacetaldehyde dehydrogenase and is overproduced after several reinoculations. Moreover, an alternative NAD-dependent dehydrogenase is recruited to resume growth in tungstate-free medium, which does not allow the production of aldehyde oxidoreductase. This alternative enzyme is overproduced and seems to have acquired a point mutation in the active center. Our research illustrates the flexibility of environmentally important bacteria in adapting their metabolic pathways to new challenges within only a few generations.
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Affiliation(s)
- G Schmitt
- Laboratory for Microbial Biochemistry, Philipps University of Marburg, Marburg, Germany
| | - F Arndt
- Laboratory for Microbial Biochemistry, Philipps University of Marburg, Marburg, Germany
| | - J Kahnt
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - J Heider
- Laboratory for Microbial Biochemistry, Philipps University of Marburg, Marburg, Germany
- LOEWE Center for Synthetic Microbiology, Marburg, Germany
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25
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Ledezma-Tejeida D, Ishida C, Collado-Vides J. Genome-Wide Mapping of Transcriptional Regulation and Metabolism Describes Information-Processing Units in Escherichia coli. Front Microbiol 2017; 8:1466. [PMID: 28824593 PMCID: PMC5540944 DOI: 10.3389/fmicb.2017.01466] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 07/20/2017] [Indexed: 11/13/2022] Open
Abstract
In the face of changes in their environment, bacteria adjust gene expression levels and produce appropriate responses. The individual layers of this process have been widely studied: the transcriptional regulatory network describes the regulatory interactions that produce changes in the metabolic network, both of which are coordinated by the signaling network, but the interplay between them has never been described in a systematic fashion. Here, we formalize the process of detection and processing of environmental information mediated by individual transcription factors (TFs), utilizing a concept termed genetic sensory response units (GENSOR units), which are composed of four components: (1) a signal, (2) signal transduction, (3) genetic switch, and (4) a response. We used experimentally validated data sets from two databases to assemble a GENSOR unit for each of the 189 local TFs of Escherichia coli K-12 contained in the RegulonDB database. Further analysis suggested that feedback is a common occurrence in signal processing, and there is a gradient of functional complexity in the response mediated by each TF, as opposed to a one regulator/one pathway rule. Finally, we provide examples of other GENSOR unit applications, such as hypothesis generation, detailed description of cellular decision making, and elucidation of indirect regulatory mechanisms.
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Affiliation(s)
- Daniela Ledezma-Tejeida
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de MéxicoCuernavaca, Mexico
| | - Cecilia Ishida
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de MéxicoCuernavaca, Mexico
| | - Julio Collado-Vides
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de MéxicoCuernavaca, Mexico
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26
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Abstract
The judicious choice of promoter to drive gene expression remains one of the most important considerations for synthetic biology applications. Constitutive promoter sequences isolated from nature are often used in laboratory settings or small-scale commercial production streams, but unconventional microbial chassis for new synthetic biology applications require well-characterized, robust and orthogonal promoters. This review provides an overview of the opportunities and challenges for synthetic promoter discovery and design, including molecular methodologies, such as saturation mutagenesis of flanking regions and mutagenesis by error-prone PCR, as well as the less familiar use of computational and statistical analyses for de novo promoter design.
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27
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Aquino P, Honda B, Jaini S, Lyubetskaya A, Hosur K, Chiu JG, Ekladious I, Hu D, Jin L, Sayeg MK, Stettner AI, Wang J, Wong BG, Wong WS, Alexander SL, Ba C, Bensussen SI, Bernstein DB, Braff D, Cha S, Cheng DI, Cho JH, Chou K, Chuang J, Gastler DE, Grasso DJ, Greifenberger JS, Guo C, Hawes AK, Israni DV, Jain SR, Kim J, Lei J, Li H, Li D, Li Q, Mancuso CP, Mao N, Masud SF, Meisel CL, Mi J, Nykyforchyn CS, Park M, Peterson HM, Ramirez AK, Reynolds DS, Rim NG, Saffie JC, Su H, Su WR, Su Y, Sun M, Thommes MM, Tu T, Varongchayakul N, Wagner TE, Weinberg BH, Yang R, Yaroslavsky A, Yoon C, Zhao Y, Zollinger AJ, Stringer AM, Foster JW, Wade J, Raman S, Broude N, Wong WW, Galagan JE. Coordinated regulation of acid resistance in Escherichia coli. BMC SYSTEMS BIOLOGY 2017; 11:1. [PMID: 28061857 PMCID: PMC5217608 DOI: 10.1186/s12918-016-0376-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 12/07/2016] [Indexed: 12/29/2022]
Abstract
Background Enteric Escherichia coli survives the highly acidic environment of the stomach through multiple acid resistance (AR) mechanisms. The most effective system, AR2, decarboxylates externally-derived glutamate to remove cytoplasmic protons and excrete GABA. The first described system, AR1, does not require an external amino acid. Its mechanism has not been determined. The regulation of the multiple AR systems and their coordination with broader cellular metabolism has not been fully explored. Results We utilized a combination of ChIP-Seq and gene expression analysis to experimentally map the regulatory interactions of four TFs: nac, ntrC, ompR, and csiR. Our data identified all previously in vivo confirmed direct interactions and revealed several others previously inferred from gene expression data. Our data demonstrate that nac and csiR directly modulate AR, and leads to a regulatory network model in which all four TFs participate in coordinating acid resistance, glutamate metabolism, and nitrogen metabolism. This model predicts a novel mechanism for AR1 by which the decarboxylation enzymes of AR2 are used with internally derived glutamate. This hypothesis makes several testable predictions that we confirmed experimentally. Conclusions Our data suggest that the regulatory network underlying AR is complex and deeply interconnected with the regulation of GABA and glutamate metabolism, nitrogen metabolism. These connections underlie and experimentally validated model of AR1 in which the decarboxylation enzymes of AR2 are used with internally derived glutamate. Electronic supplementary material The online version of this article (doi:10.1186/s12918-016-0376-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Patricia Aquino
- Department of Biomedical Engineering, Boston University, Boston, USA.,BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Brent Honda
- Department of Biomedical Engineering, Boston University, Boston, USA
| | - Suma Jaini
- Department of Biomedical Engineering, Boston University, Boston, USA
| | | | - Krutika Hosur
- Department of Biomedical Engineering, Boston University, Boston, USA.,BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Joanna G Chiu
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Iriny Ekladious
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Dongjian Hu
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Lin Jin
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Marianna K Sayeg
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Arion I Stettner
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Julia Wang
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Brandon G Wong
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Winnie S Wong
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | | | - Cong Ba
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Seth I Bensussen
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - David B Bernstein
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Dana Braff
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Susie Cha
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Daniel I Cheng
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Jang Hwan Cho
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Kenny Chou
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - James Chuang
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Daniel E Gastler
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Daniel J Grasso
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | | | - Chen Guo
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Anna K Hawes
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Divya V Israni
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Saloni R Jain
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Jessica Kim
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Junyu Lei
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Hao Li
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - David Li
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Qian Li
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | | | - Ning Mao
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Salwa F Masud
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Cari L Meisel
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Jing Mi
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | | | - Minhee Park
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Hannah M Peterson
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Alfred K Ramirez
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Daniel S Reynolds
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Nae Gyune Rim
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Jared C Saffie
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Hang Su
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Wendell R Su
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Yaqing Su
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Meng Sun
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Meghan M Thommes
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Tao Tu
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | | | - Tyler E Wagner
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | | | - Rouhui Yang
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | | | - Christine Yoon
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | - Yanyu Zhao
- BE605 Course, Biomedical Engineering, Boston University, Boston, USA
| | | | - Anne M Stringer
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - John W Foster
- Department of Microbiology and Immunology, University of South Alabama College of Medicine, Mobile, AL, 36688, USA
| | - Joseph Wade
- Wadsworth Center, New York State Department of Health, Albany, NY, USA.,Department of Biomedical Sciences, University at Albany, Albany, NY, USA
| | - Sahadaven Raman
- Department of Microbiology and Immunology, University of South Alabama College of Medicine, Mobile, AL, 36688, USA
| | - Natasha Broude
- Department of Biomedical Engineering, Boston University, Boston, USA
| | - Wilson W Wong
- Department of Biomedical Engineering, Boston University, Boston, USA
| | - James E Galagan
- Department of Biomedical Engineering, Boston University, Boston, USA. .,Bioinformatics program, Boston University, Boston, USA. .,National Emerging Infectious Diseases Laboratory, Boston University, Boston, USA.
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28
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Larsen Ø, Karlsen OA. Transcriptomic profiling of Methylococcus capsulatus (Bath) during growth with two different methane monooxygenases. Microbiologyopen 2016; 5:254-67. [PMID: 26687591 PMCID: PMC4831470 DOI: 10.1002/mbo3.324] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 11/04/2015] [Accepted: 11/06/2015] [Indexed: 11/23/2022] Open
Abstract
Methylococcus capsulatus (Bath) is a methanotroph that possesses both a membrane-embedded (pMMO) and a soluble methane monooxygenase (sMMO). The expression of these two MMO's is tightly controlled by the availability of copper in the growth medium, but the underlying mechanisms and the number of genes involved in this switch in methane oxidation is not yet fully elucidated. Microarray analyses were used to assess the transcriptome in cells producing either pMMO or sMMO. A total of 137 genes were differentially expressed, with 87 genes showing a significant up-regulation during sMMO production. The majority of the differentially expressed genes could be assigned to functional roles in the energy metabolism and transport. Furthermore, three copper responding gene clusters were discovered, including an extended cluster that also harbors the genes for sMMO. Our data also indicates that major changes takes place in the respiratory chain between pMMO- and sMMO-producing cells, and that quinone are predominantly used as the electron donors for methane oxidation by pMMO. Intriguingly, a large proportion of the differentially expressed genes between pMMO- and sMMO-producing cells encode c-type cytochromes. By combining microarray- and mass spectrometry data, a total of 35 c-type cytochromes are apparently expressed in M. capsulatus when grown in nitrate mineral salt medium with methane as sole energy and carbon source, and the expression of 21 of these respond to the availability of copper. Interestingly, several of these c-type cytochromes are recovered from the cell surface, suggesting that extracellular electron transfers may occur in M. capsulatus.
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Affiliation(s)
- Øivind Larsen
- Uni Research EnvironmentThormøhlensgate 49bBergen5006Norway
| | - Odd A. Karlsen
- Department of Molecular BiologyUniversity of BergenBergenNorway
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29
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Abstract
Transcription factors (TFs) play a central role in regulating gene expression in all bacteria. Yet until recently, studies of TF binding were limited to a small number of factors at a few genomic locations. Chromatin immunoprecipitation followed by sequencing (ChIP-Seq) provides the ability to map binding sites globally for TFs, and the scalability of the technology enables the ability to map binding sites for every DNA binding protein in a prokaryotic organism. We have developed a protocol for ChIP-Seq tailored for use with mycobacteria and an analysis pipeline for processing the resulting data. The protocol and pipeline have been used to map over 100 TFs from Mycobacterium tuberculosis, as well as numerous TFs from related mycobacteria and other bacteria. The resulting data provide evidence that the long-accepted spatial relationship between TF binding site, promoter motif, and the corresponding regulated gene may be too simple a paradigm, failing to adequately capture the variety of TF binding sites found in prokaryotes. In this article we describe the protocol and analysis pipeline, the validation of these methods, and the results of applying these methods to M. tuberculosis.
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30
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Wolf D, Rippa V, Mobarec JC, Sauer P, Adlung L, Kolb P, Bischofs IB. The quorum-sensing regulator ComA from Bacillus subtilis activates transcription using topologically distinct DNA motifs. Nucleic Acids Res 2015; 44:2160-72. [PMID: 26582911 PMCID: PMC4797271 DOI: 10.1093/nar/gkv1242] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 10/30/2015] [Indexed: 11/27/2022] Open
Abstract
ComA-like transcription factors regulate the quorum response in numerous Gram-positive bacteria. ComA proteins belong to the tetrahelical helix-turn-helix superfamily of transcriptional activators, which bind as homodimers to inverted sequence repeats in the DNA. Here, we report that ComA from Bacillus subtilis recognizes a topologically distinct motif, in which the binding elements form a direct repeat. We provide in vitro and in vivo evidence that the canonical and non-canonical site play an important role in facilitating type I and type II promoter activation, respectively, by interacting with different subunits of RNA polymerase. We furthermore show that there is a variety of contexts in which the non-canonical site can occur and identify new direct target genes that are located within the integrative and conjugative element ICEBs1. We therefore suggest that ComA acts as a multifunctional transcriptional activator and provides a striking example for complexity in protein–DNA interactions that evolved in the context of quorum sensing.
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Affiliation(s)
- Diana Wolf
- Center for Molecular Biology (ZMBH) and Center for the Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), University of Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
| | - Valentina Rippa
- Center for Molecular Biology (ZMBH) and Center for the Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), University of Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
| | - Juan Carlos Mobarec
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marbacher Weg 6, 35032 Marburg, Germany
| | - Patricia Sauer
- Center for Molecular Biology (ZMBH) and Center for the Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), University of Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
| | - Lorenz Adlung
- Center for Molecular Biology (ZMBH) and Center for the Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), University of Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marbacher Weg 6, 35032 Marburg, Germany
| | - Ilka B Bischofs
- Center for Molecular Biology (ZMBH) and Center for the Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), University of Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
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31
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Abstract
The pathways in Escherichia coli and (largely by analogy) S. enterica remain the paradigm of bacterial lipid synthetic pathways, although recently considerable diversity among bacteria in the specific areas of lipid synthesis has been demonstrated. The structural biology of the fatty acid synthetic proteins is essentially complete. However, the membrane-bound enzymes of phospholipid synthesis remain recalcitrant to structural analyses. Recent advances in genetic technology have allowed the essentialgenes of lipid synthesis to be tested with rigor, and as expected most genes are essential under standard growth conditions. Conditionally lethal mutants are available in numerous genes, which facilitates physiological analyses. The array of genetic constructs facilitates analysis of the functions of genes from other organisms. Advances in mass spectroscopy have allowed very accurate and detailed analyses of lipid compositions as well as detection of the interactions of lipid biosynthetic proteins with one another and with proteins outside the lipid pathway. The combination of these advances has resulted in use of E. coli and S. enterica for discovery of new antimicrobials targeted to lipid synthesis and in deciphering the molecular actions of known antimicrobials. Finally,roles for bacterial fatty acids other than as membrane lipid structural components have been uncovered. For example, fatty acid synthesis plays major roles in the synthesis of the essential enzyme cofactors, biotin and lipoic acid. Although other roles for bacterial fatty acids, such as synthesis of acyl-homoserine quorum-sensing molecules, are not native to E. coli introduction of the relevant gene(s) synthesis of these foreign molecules readily proceeds and the sophisticated tools available can used to decipher the mechanisms of synthesis of these molecules.
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32
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Abstract
The biosynthesis of serine, glycine, and one-carbon (C1) units constitutes a major metabolic pathway in Escherichia coli and Salmonella enterica serovar Typhimurium. C1 units derived from serine and glycine are used in the synthesis of purines, histidine, thymine, pantothenate, and methionine and in the formylation of the aminoacylated initiator fMet-TRNAfMet used to start translation in E. coli and serovar Typhimurium. The need for serine, glycine, and C1 units in many cellular functions makes it necessary for the genes encoding enzymes for their synthesis to be carefully regulated to meet the changing demands of the cell for these intermediates. This review discusses the regulation of the following genes: serA, serB, and serC; gly gene; gcvTHP operon; lpdA; gcvA and gcvR; and gcvB genes. Threonine utilization (the Tut cycle) constitutes a secondary pathway for serine and glycine biosynthesis. L-Serine inhibits the growth of E. coli cells in GM medium, and isoleucine releases this growth inhibition. The E. coli glycine transport system (Cyc) has been shown to transport glycine, D-alanine, D-serine, and the antibiotic D-cycloserine. Transport systems often play roles in the regulation of gene expression, by transporting effector molecules into the cell, where they are sensed by soluble or membrane-bound regulatory proteins.
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33
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Regulation Mechanism of the ald Gene Encoding Alanine Dehydrogenase in Mycobacterium smegmatis and Mycobacterium tuberculosis by the Lrp/AsnC Family Regulator AldR. J Bacteriol 2015. [PMID: 26195594 DOI: 10.1128/jb.00453-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED In the presence of alanine, AldR, which belongs to the Lrp/AsnC family of transcriptional regulators and regulates ald encoding alanine dehydrogenase in Mycobacterium smegmatis, changes its quaternary structure from a homodimer to an octamer with an open-ring conformation. Four AldR-binding sites (O2, O1, O4, and O3) with a consensus sequence of GA/T-N2-NWW/WWN-N2-A/TC were identified upstream of the M. smegmatis ald gene by means of DNase I footprinting analysis. O2, O1, and O4 are required for the induction of ald expression by alanine, while O3 is directly involved in the repression of ald expression. In addition to O3, both O1 and O4 are also necessary for full repression of ald expression in the absence of alanine, due to cooperative binding of AldR dimers to O1, O4, and O3. Binding of a molecule of the AldR octamer to the ald control region was demonstrated to require two AldR-binding sites separated by three helical turns between their centers and one additional binding site that is in phase with the two AldR-binding sites. The cooperative binding of AldR dimers to DNA requires three AldR-binding sites that are aligned with a periodicity of three helical turns. The aldR gene is negatively autoregulated independently of alanine. Comparative analysis of ald expression of M. smegmatis and Mycobacterium tuberculosis in conjunction with sequence analysis of both ald control regions led us to suggest that the expression of the ald genes in both mycobacterial species is regulated by the same mechanism. IMPORTANCE In mycobacteria, alanine dehydrogenase (Ald) is the enzyme required both to utilize alanine as a nitrogen source and to grow under hypoxic conditions by maintaining the redox state of the NADH/NAD(+) pool. Expression of the ald gene was reported to be regulated by the AldR regulator that belongs to the Lrp/AsnC (feast/famine) family, but the underlying mechanism was unknown. This study revealed the regulation mechanism of ald in Mycobacterium smegmatis and Mycobacterium tuberculosis. Furthermore, a generalized arrangement pattern of cis-acting regulatory sites for Lrp/AsnC (feast/famine) family regulators is suggested in this study.
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34
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The DNA-binding network of Mycobacterium tuberculosis. Nat Commun 2015; 6:5829. [PMID: 25581030 PMCID: PMC4301838 DOI: 10.1038/ncomms6829] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 11/07/2014] [Indexed: 12/20/2022] Open
Abstract
Mycobacterium tuberculosis (MTB) infects 30% of all humans and kills someone every 20-30 s. Here we report genome-wide binding for ~80% of all predicted MTB transcription factors (TFs), and assayed global expression following induction of each TF. The MTB DNA-binding network consists of ~16,000 binding events from 154 TFs. We identify >50 TF-DNA consensus motifs and >1,150 promoter-binding events directly associated with proximal gene regulation. An additional ~4,200 binding events are in promoter windows and represent strong candidates for direct transcriptional regulation under appropriate environmental conditions. However, we also identify >10,000 'dormant' DNA-binding events that cannot be linked directly with proximal transcriptional control, suggesting that widespread DNA binding may be a common feature that should be considered when developing global models of coordinated gene expression.
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35
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Amouyal M. From adjacent activation in Escherichia coli and DNA cyclization to eukaryotic enhancers: the elements of a puzzle. Front Genet 2014; 5:371. [PMID: 25404937 PMCID: PMC4217526 DOI: 10.3389/fgene.2014.00371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 10/04/2014] [Indexed: 11/13/2022] Open
Abstract
Deoxyribonucleic acid cyclization, Escherichia coli lac repressor binding to two spaced lac operators and repression enhancement can be successfully used for a better understanding of the conditions required for interaction between eukaryotic enhancers and the machinery of transcription initiation. Chronologically, the DNA looping model has first accounted for the properties initially defining enhancers, i.e., independence of action with distance or orientation with respect to the start of transcription. It has also predicted enhancer activity or its disruption at short distance (site orientation, alignment between promoter and enhancer sites), with high-order complexes of protein, or with transcription factor concentrations close or different from the wild-type situation. In another step, histones have been introduced into the model to further adapt it to eukaryotes. They in fact favor DNA cyclization in vitro. The resulting DNA compaction might explain the difference counted in base pairs in the distance of action between eukaryotic transcription enhancers and prokaryotic repression enhancers. The lac looping system provides a potential tool for analysis of this discrepancy and of chromatin state directly in situ. Furthermore, as predicted by the model, the contribution of operators O2 and O3 to repression of the lac operon clearly depends on the lac repressor level in the cell and is prevented in strains overproducing lac repressor. By extension, gene regulation especially that linked to cell fate, should also depend on transcription factor levels, providing a potential tool for cellular therapy. In parallel, a new function of the O1–O3 loop completes the picture of lac repression. The O1–O3 loop would at the same time ensure high efficiency of repression, inducibility through the low-affinity sites and limitation of the level of repressor through self-repression of the lac repressor. Last, the DNA looping model can be successfully adapted to the enhancer auxiliary elements known as insulators.
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Affiliation(s)
- Michèle Amouyal
- Interactions à Distance, Centre National de la Recherche Scientifique Paris, France
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Guazzaroni ME, Silva-Rocha R. Expanding the logic of bacterial promoters using engineered overlapping operators for global regulators. ACS Synth Biol 2014; 3:666-75. [PMID: 25036188 DOI: 10.1021/sb500084f] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The understanding of how the architecture of cis-regulatory elements at bacterial promoters determines their final output is of central interest in modern biology. In this work, we attempt to gain insight into this process by analyzing complex promoter architectures in the model organism Escherichia coli. By focusing on the relationship between different TFs at the genomic scale in terms of their binding site arrangement and their effect on the target promoters, we found no strong constraint limiting the combinatorial assembly of TF pairs in E. coli. More strikingly, overlapping binding sites were found equally associated with both equivalent (both TFs have the same effect on the promoter) and opposite (one TF activates while the other repress the promoter) effects on gene expression. With this information on hand, we set an in silico approach to design overlapping sites for three global regulators (GRs) of E. coli, specifically CRP, Fis, and IHF. Using random sequence assembly and an evolutionary algorithm, we were able to identify potential overlapping operators for all TF pairs. In order to validate our prediction, we constructed two lac promoter variants containing overlapping sites for CRP and IHF designed in silico. By assaying the synthetic promoters using a GFP reporter system, we demonstrated that these variants were functional and activated by CRP and IHF in vivo. Taken together, presented results add new information on the mechanisms of signal integration in bacterial promoters and provide new strategies for the engineering of synthetic regulatory circuits in bacteria.
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Shong J, Collins CH. Quorum sensing-modulated AND-gate promoters control gene expression in response to a combination of endogenous and exogenous signals. ACS Synth Biol 2014; 3:238-46. [PMID: 24175658 DOI: 10.1021/sb4000965] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have constructed and characterized two synthetic AND-gate promoters that require both a quorum-sensing (QS) signal and an exogenously added inducer to turn on gene expression. The engineered promoters, LEE and TTE, contain binding sites for the QS-dependent repressor, EsaR, and either LacI or TetR, and they are induced by an acyl-homoserine lactone (AHL) signal and IPTG or aTc. Although repression of both LEE and TTE by wild-type EsaR was observed, induction of gene expression at physiologically relevant concentrations of AHL required the use of an EsaR variant with higher signal sensitivity. Gene expression from both LEE and TTE was shown to require both signal molecules, and gene expression above background levels was not observed with either signal alone. We added endogenous production of AHL to evaluate the ability of the promoters to function in a QS-dependent manner and observed that gene expression increased as a function of cell density only in the presence of exogenously added IPTG or aTc. Cell-cell communication-dependent AND-gate behaviors were demonstrated using an agar plate assay, where cells containing the engineered promoters were shown to respond to AHL produced by a second E. coli strain only in the presence of exogenously added IPTG or aTc. The promoters described in this work demonstrate that EsaR and its target DNA sequence can be used to engineer new promoters to respond to cell density or cell-cell communication. Further, the AND-gate promoters described here may serve as a template for new regulatory systems that integrate QS and the presence of key metabolites or other environmental cues to enable dynamic changes in gene expression for metabolic engineering applications.
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Affiliation(s)
- Jasmine Shong
- Department of Chemical
and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy New York 12180 United States of America
- Center for Biotechnology
and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy New York 12180 United States of America
| | - Cynthia H. Collins
- Department of Chemical
and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy New York 12180 United States of America
- Center for Biotechnology
and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy New York 12180 United States of America
- Department of Biology, Rensselaer Polytechnic Institute, 110 8th Street, Troy New
York 12180 United States of America
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Shimada T, Yamazaki Y, Tanaka K, Ishihama A. The whole set of constitutive promoters recognized by RNA polymerase RpoD holoenzyme of Escherichia coli. PLoS One 2014; 9:e90447. [PMID: 24603758 PMCID: PMC3946193 DOI: 10.1371/journal.pone.0090447] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 02/01/2014] [Indexed: 01/08/2023] Open
Abstract
The promoter selectivity of Escherichia coli RNA polymerase is determined by the sigma subunit with promoter recognition activity. The model prokaryote Escherichia coli contains seven species of the sigma subunit, each recognizing a specific set of promoters. The major sigma subunit, sigma-70 encoded by rpoD, plays a major role in transcription of growth-related genes. Concomitant with the increase in detection of promoters functioning in vivo under various stressful conditions, the variation is expanding in the consensus sequence of RpoD promoters. In order to identify the canonical sequence of "constitutive promoters" that are recognized by the RNA polymerase holoenzyme containing RpoD sigma in the absence of supporting transcription factors, an in vitro mixed transcription assay was carried out using a whole set of variant promoters, each harboring one base replacement, within the model promoter with the conserved -35 and -10 sequences of RpoD promoters. The consensus sequences, TTGACA(-35) and TATAAT(-10), were identified to be ideal for the maximum level of open complex formation and the highest rate of promoter opening, respectively. For identification of the full range of constitutive promoters on the E. coli genome, a total of 2,701 RpoD holoenzyme-binding sites were identified by Genomic SELEX screening, and using the reconfirmed consensus promoter sequence, a total of maximum 669 constitutive promoters were identified, implying that the majority of hitherto identified promoters represents the TF-dependent "inducible promoters". One unique feature of the constitutive promoters is the high level of promoter sequence conservation, about 85% carrying five-out-of-six agreements with -35 or -10 consensus sequence. The list of constitutive promoters provides the community resource toward estimation of the inducible promoters that operate under various stressful conditions in nature.
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Affiliation(s)
- Tomohiro Shimada
- Department of Frontier Biosience, Hosei University, Koganai, Tokyo, Japan
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, Japan
- Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuda, Yokohama, Japan
| | - Yukiko Yamazaki
- Genetics Strains Research Institute, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Kan Tanaka
- Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuda, Yokohama, Japan
| | - Akira Ishihama
- Department of Frontier Biosience, Hosei University, Koganai, Tokyo, Japan
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, Japan
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van Heeswijk WC, Westerhoff HV, Boogerd FC. Nitrogen assimilation in Escherichia coli: putting molecular data into a systems perspective. Microbiol Mol Biol Rev 2013; 77:628-95. [PMID: 24296575 PMCID: PMC3973380 DOI: 10.1128/mmbr.00025-13] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We present a comprehensive overview of the hierarchical network of intracellular processes revolving around central nitrogen metabolism in Escherichia coli. The hierarchy intertwines transport, metabolism, signaling leading to posttranslational modification, and transcription. The protein components of the network include an ammonium transporter (AmtB), a glutamine transporter (GlnHPQ), two ammonium assimilation pathways (glutamine synthetase [GS]-glutamate synthase [glutamine 2-oxoglutarate amidotransferase {GOGAT}] and glutamate dehydrogenase [GDH]), the two bifunctional enzymes adenylyl transferase/adenylyl-removing enzyme (ATase) and uridylyl transferase/uridylyl-removing enzyme (UTase), the two trimeric signal transduction proteins (GlnB and GlnK), the two-component regulatory system composed of the histidine protein kinase nitrogen regulator II (NRII) and the response nitrogen regulator I (NRI), three global transcriptional regulators called nitrogen assimilation control (Nac) protein, leucine-responsive regulatory protein (Lrp), and cyclic AMP (cAMP) receptor protein (Crp), the glutaminases, and the nitrogen-phosphotransferase system. First, the structural and molecular knowledge on these proteins is reviewed. Thereafter, the activities of the components as they engage together in transport, metabolism, signal transduction, and transcription and their regulation are discussed. Next, old and new molecular data and physiological data are put into a common perspective on integral cellular functioning, especially with the aim of resolving counterintuitive or paradoxical processes featured in nitrogen assimilation. Finally, we articulate what still remains to be discovered and what general lessons can be learned from the vast amounts of data that are available now.
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Synthetic promoters functional in Francisella novicida and Escherichia coli. Appl Environ Microbiol 2013; 80:226-34. [PMID: 24141126 DOI: 10.1128/aem.02793-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this work, we describe the identification of synthetic, controllable promoters that function in the bacterial pathogen Francisella novicida, a model facultative intracellular pathogen. Synthetic DNA fragments consisting of the tetracycline operator (tetO) flanked by a random nucleotide sequence were inserted into a Francisella novicida shuttle plasmid upstream of a promoterless artificial operon containing the reporter genes cat and lacZ. Fragments able to promote transcription were selected for based on their ability to drive expression of the cat gene, conferring chloramphenicol resistance. Promoters of various strengths were found, many of which were repressed in the presence of the tetracycline repressor (TetR) and promoted transcription only in the presence of the TetR inducer anhydrotetracycline. A subset of both constitutive and inducible synthetic promoters were characterized to find their induction ratios and to identify their transcription start sites. In cases where tetO was located between or downstream of the -10 and -35 regions of the promoter, control by TetR was observed. If the tetO region was upstream of the -35 region by more than 9 bp, it did not confer TetR control. We found that three of three promoters isolated in F. novicida functioned at a comparable level in E. coli; however, none of the 10 promoters isolated in E. coli functioned at a significant level in F. novicida. Our results allowed us to isolate minimal F. novicida promoters of 47 and 48 bp in length.
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Shong J, Collins CH. Engineering the esaR promoter for tunable quorum sensing- dependent gene expression. ACS Synth Biol 2013; 2:568-75. [PMID: 23879176 DOI: 10.1021/sb4000433] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Quorum sensing (QS) systems enable bacteria to coordinate their behavior as a function of local population density and are often used in synthetic systems that require cell−cell communication. We have engineered the esaR promoter, P(esaR), which is repressed by the QS regulator E(saR). E(saR)-dependent gene expression from P(esaR) is induced by 3-oxo-hexanoyl-homoserine lactone (3OC6HSL). Here, we report a set of modified P(esaR) promoters that contain a second E(saR) binding site. We observed changes in gene expression levels, regulatory range, 3OC6HSL sensitivity, and the regulatory role of E(saR) that are dependent on the position of the second binding site. Combining the new promoters with endogenous 3OC6HSL production led to QS-dependent systems that exhibit a range of expression levels and timing. These promoters represent a new set of tools for modulating QS-dependent gene expression and may be used to tune the regulation of multiple genes in response to a single QS signal.
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Affiliation(s)
- Jasmine Shong
- Department of Chemical and Biological
Engineering, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180, United States
| | - Cynthia H. Collins
- Department of Chemical and Biological
Engineering, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180, United States
- Department of Biology, Rensselaer Polytechnic Institute, 110 Eighth Street,
Troy, New York 12180, United States
- Center for Biotechnology and Interdisciplinary
Studies, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180, United States
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Kakei Y, Ogo Y, Itai RN, Kobayashi T, Yamakawa T, Nakanishi H, Nishizawa NK. Development of a novel prediction method of cis-elements to hypothesize collaborative functions of cis-element pairs in iron-deficient rice. RICE (NEW YORK, N.Y.) 2013; 6:22. [PMID: 24279975 PMCID: PMC4883709 DOI: 10.1186/1939-8433-6-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 09/13/2013] [Indexed: 05/20/2023]
Abstract
BACKGROUND Cis-acting elements are essential genomic sequences that control gene expression. In higher eukaryotes, a series of cis-elements function cooperatively. However, further studies are required to examine the co-regulation of multiple cis-elements on a promoter. The aim of this study was to propose a model of cis-element networks that cooperatively regulate gene expression in rice under iron (Fe) deficiency. RESULTS We developed a novel clustering-free method, microarray-associated motif analyzer (MAMA), to predict novel cis-acting elements based on weighted sequence similarities and gene expression profiles in microarray analyses. Simulation of gene expression was performed using a support vector machine and based on the presence of predicted motifs and motif pairs. The accuracy of simulated gene expression was used to evaluate the quality of prediction and to optimize the parameters used in this method. Based on sequences of Oryza sativa genes upregulated by Fe deficiency, MAMA returned experimentally identified cis-elements responsible for Fe deficiency in O. sativa. When this method was applied to O. sativa subjected to zinc deficiency and Arabidopsis thaliana subjected to salt stress, several novel candidate cis-acting elements that overlap with known cis-acting elements, such as ZDRE, ABRE, and DRE, were identified. After optimization, MAMA accurately simulated more than 87% of gene expression. Predicted motifs strongly co-localized in the upstream regions of regulated genes and sequences around transcription start sites. Furthermore, in many cases, the separation (in bp) between co-localized motifs was conserved, suggesting that predicted motifs and the separation between them were important in the co-regulation of gene expression. CONCLUSIONS Our results are suggestive of a typical sequence model for Fe deficiency-responsive promoters and some strong candidate cis-elements that function cooperatively with known cis-elements.
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Affiliation(s)
- Yusuke Kakei
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
- />Plant Biotechnology Division, Yokohama City University, Kihara Institute for Biological Research Maiokacho, 641-12, Totsuka, Yokohama, Kanagawa 244-0813 Japan
| | - Yuko Ogo
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
- />Functional Transgenic Crops Research Unit, Genetically Modified Organism Research Center National Institute of Agrobiological Sciences, Kannondai 2-1-2, 305-8602 Tsukuba, Ibaraki Japan
| | - Reiko N Itai
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
| | - Takanori Kobayashi
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
- />Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, 921-8836 Nonoichi-machi, Ishikawa Japan
- />Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, 921-8836 Nonoichi-machi, Ishikawa Japan
| | - Takashi Yamakawa
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
| | - Hiromi Nakanishi
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
| | - Naoko K Nishizawa
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
- />Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, 921-8836 Nonoichi-machi, Ishikawa Japan
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Balderas-Martínez YI, Savageau M, Salgado H, Pérez-Rueda E, Morett E, Collado-Vides J. Transcription factors in Escherichia coli prefer the holo conformation. PLoS One 2013; 8:e65723. [PMID: 23776535 PMCID: PMC3680503 DOI: 10.1371/journal.pone.0065723] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 04/26/2013] [Indexed: 11/18/2022] Open
Abstract
The transcriptional regulatory network of Escherichia coli K-12 is among the best studied gene networks of any living cell. Transcription factors bind to DNA either with their effector bound (holo conformation), or as a free protein (apo conformation) regulating transcription initiation. By using RegulonDB, the functional conformations (holo or apo) of transcription factors, and their mode of regulation (activator, repressor, or dual) were exhaustively analyzed. We report a striking discovery in the architecture of the regulatory network, finding a strong under-representation of the apo conformation (without allosteric metabolite) of transcription factors when binding to their DNA sites to activate transcription. This observation is supported at the level of individual regulatory interactions on promoters, even if we exclude the promoters regulated by global transcription factors, where three-quarters of the known promoters are regulated by a transcription factor in holo conformation. This genome-scale analysis enables us to ask what are the implications of these observations for the physiology and for our understanding of the ecology of E. coli. We discuss these ideas within the framework of the demand theory of gene regulation.
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Affiliation(s)
- Yalbi Itzel Balderas-Martínez
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- * E-mail: (YIB-M); (JC-V)
| | - Michael Savageau
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
| | - Heladia Salgado
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Ernesto Pérez-Rueda
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Enrique Morett
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Julio Collado-Vides
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- * E-mail: (YIB-M); (JC-V)
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Regulation of the ald gene encoding alanine dehydrogenase by AldR in Mycobacterium smegmatis. J Bacteriol 2013; 195:3610-20. [PMID: 23749971 DOI: 10.1128/jb.00482-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The regulatory gene aldR was identified 95 bp upstream of the ald gene encoding L-alanine dehydrogenase in Mycobacterium smegmatis. The AldR protein shows sequence similarity to the regulatory proteins of the Lrp/AsnC family. Using an aldR deletion mutant, we demonstrated that AldR serves as both activator and repressor for the regulation of ald gene expression, depending on the presence or absence of L-alanine. The purified AldR protein exists as a homodimer in the absence of L-alanine, while it adopts the quaternary structure of a homohexamer in the presence of L-alanine. The binding affinity of AldR for the ald control region was shown to be increased significantly by L-alanine. Two AldR binding sites (O1 and O2) with the consensus sequence GA-N₂-ATC-N₂-TC and one putative AldR binding site with the sequence GA-N₂-GTT-N₂-TC were identified upstream of the ald gene. Alanine and cysteine were demonstrated to be the effector molecules directly involved in the induction of ald expression. The cellular level of L-alanine was shown to be increased in M. smegmatis cells grown under hypoxic conditions, and the hypoxic induction of ald expression appears to be mediated by AldR, which senses the intracellular level of alanine.
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Characterization of the ospZ promoter in Shigella flexneri and its regulation by VirB and H-NS. J Bacteriol 2013; 195:2562-72. [PMID: 23543709 DOI: 10.1128/jb.00212-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
OspZ is an effector protein of the type III secretion system in Shigella spp. that downregulates the human inflammatory response during bacterial infection. The ospZ gene is located on the large virulence plasmid of Shigella. Many genes on this plasmid are transcriptionally repressed by the nucleoid structuring protein H-NS and derepressed by VirB, a DNA-binding protein that displays homology to the plasmid partitioning proteins ParB and SopB. In this study, we characterized the ospZ promoter and investigated its regulation by H-NS and VirB in Shigella flexneri. We show that H-NS represses and VirB partially derepresses the ospZ promoter. H-NS-mediated repression requires sequences located between -731 and -412 relative to the beginning of the ospZ gene. Notably, the VirB-dependent derepression of ospZ requires the same VirB binding sites as are required for the VirB-dependent derepression of the divergent icsP gene. These sites are centered 425 bp upstream of the ospZ gene but over 1 kb upstream of the icsP transcription start site. Although these VirB binding sites lie closer to ospZ than icsP, the VirB-dependent increase in ospZ promoter activity is lower than that observed at the icsP promoter. This indicates that the proximity of VirB binding sites to Shigella promoters does not necessarily correlate with the level of VirB-dependent derepression. These findings have implications for virulence gene regulation in Shigella and other pathogens that control gene expression using mechanisms of transcriptional repression and derepression.
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Salgado H, Peralta-Gil M, Gama-Castro S, Santos-Zavaleta A, Muñiz-Rascado L, García-Sotelo JS, Weiss V, Solano-Lira H, Martínez-Flores I, Medina-Rivera A, Salgado-Osorio G, Alquicira-Hernández S, Alquicira-Hernández K, López-Fuentes A, Porrón-Sotelo L, Huerta AM, Bonavides-Martínez C, Balderas-Martínez YI, Pannier L, Olvera M, Labastida A, Jiménez-Jacinto V, Vega-Alvarado L, Del Moral-Chávez V, Hernández-Alvarez A, Morett E, Collado-Vides J. RegulonDB v8.0: omics data sets, evolutionary conservation, regulatory phrases, cross-validated gold standards and more. Nucleic Acids Res 2012. [PMID: 23203884 PMCID: PMC3531196 DOI: 10.1093/nar/gks1201] [Citation(s) in RCA: 351] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
This article summarizes our progress with RegulonDB (http://regulondb.ccg.unam.mx/) during the past 2 years. We have kept up-to-date the knowledge from the published literature regarding transcriptional regulation in Escherichia coli K-12. We have maintained and expanded our curation efforts to improve the breadth and quality of the encoded experimental knowledge, and we have implemented criteria for the quality of our computational predictions. Regulatory phrases now provide high-level descriptions of regulatory regions. We expanded the assignment of quality to various sources of evidence, particularly for knowledge generated through high-throughput (HT) technology. Based on our analysis of most relevant methods, we defined rules for determining the quality of evidence when multiple independent sources support an entry. With this latest release of RegulonDB, we present a new highly reliable larger collection of transcription start sites, a result of our experimental HT genome-wide efforts. These improvements, together with several novel enhancements (the tracks display, uploading format and curational guidelines), address the challenges of incorporating HT-generated knowledge into RegulonDB. Information on the evolutionary conservation of regulatory elements is also available now. Altogether, RegulonDB version 8.0 is a much better home for integrating knowledge on gene regulation from the sources of information currently available.
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Affiliation(s)
- Heladia Salgado
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, A.P. 565-A, Cuernavaca, Morelos 62100
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Amouyal M. TFC6 (TFIIIC Subunit): A Bridge between Prokaryotic and Eukaryotic Gene Regulation. Front Genet 2012; 3:64. [PMID: 22536206 PMCID: PMC3334521 DOI: 10.3389/fgene.2012.00064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 04/04/2012] [Indexed: 11/13/2022] Open
Affiliation(s)
- Michèle Amouyal
- Interactions à Distance, Centre National de la Recherche ScientifiqueParis, France,*Correspondence:
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Ishihama A. Prokaryotic genome regulation: a revolutionary paradigm. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2012; 88:485-508. [PMID: 23138451 PMCID: PMC3511978 DOI: 10.2183/pjab.88.485] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 08/31/2012] [Indexed: 06/01/2023]
Abstract
After determination of the whole genome sequence, the research frontier of bacterial molecular genetics has shifted to reveal the genome regulation under stressful conditions in nature. The gene selectivity of RNA polymerase is modulated after interaction with two groups of regulatory proteins, 7 sigma factors and 300 transcription factors. For identification of regulation targets of transcription factors in Escherichia coli, we have developed Genomic SELEX system and subjected to screening the binding sites of these factors on the genome. The number of regulation targets by a single transcription factor was more than those hitherto recognized, ranging up to hundreds of promoters. The number of transcription factors involved in regulation of a single promoter also increased to as many as 30 regulators. The multi-target transcription factors and the multi-factor promoters were assembled into complex networks of transcription regulation. The most complex network was identified in the regulation cascades of transcription of two master regulators for planktonic growth and biofilm formation.
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Affiliation(s)
- Akira Ishihama
- Department of Frontier Bioscience and Micro-Nano Technology Research Center, Hosei University, Koganei, Tokyo 184-8584, Japan.
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49
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Brucella melitensis cyclic di-GMP phosphodiesterase BpdA controls expression of flagellar genes. J Bacteriol 2011; 193:5683-91. [PMID: 21856843 DOI: 10.1128/jb.00428-11] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Brucella melitensis encounters a variety of conditions and stimuli during its life cycle--including environmental growth, intracellular infection, and extracellular dissemination--which necessitates flexibility of bacterial signaling to promote virulence. Cyclic-di-GMP is a bacterial secondary signaling molecule that plays an important role in adaptation to changing environments and altering virulence in a number of bacteria. To investigate the role of cyclic-di-GMP in B. melitensis, all 11 predicted cyclic-di-GMP-metabolizing proteins were separately deleted and the effect on virulence was determined. Three of these cyclic-di-GMP-metabolizing proteins were found to alter virulence. Deletion of the bpdA and bpdB genes resulted in attenuation of virulence of the bacterium, while deletion of the cgsB gene produced a hypervirulent strain. In a Vibrio reporter system to monitor apparent alteration in levels of cyclic-di-GMP, both BpdA and BpdB displayed a phenotype consistent with cyclic-di-GMP-specific phosphodiesterases, while CgsB displayed a cyclic-di-GMP synthase phenotype. Further analysis found that deletion of bpdA resulted in a dramatic decrease in flagellar promoter activities, and a flagellar mutant showed similar phenotypes to the bpdA and bpdB mutant strains in mouse models of infection. These data indicate a potential role for regulation of flagella in Brucella melitensis via cyclic-di-GMP.
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Evidence-based annotation of transcripts and proteins in the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough. J Bacteriol 2011; 193:5716-27. [PMID: 21840973 DOI: 10.1128/jb.05563-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We used high-resolution tiling microarrays and 5' RNA sequencing to identify transcripts in Desulfovibrio vulgaris Hildenborough, a model sulfate-reducing bacterium. We identified the first nucleotide position for 1,124 transcripts, including 54 proteins with leaderless transcripts and another 72 genes for which a major transcript initiates within the upstream protein-coding gene, which confounds measurements of the upstream gene's expression. Sequence analysis of these promoters showed that D. vulgaris prefers -10 and -35 boxes different from those preferred by Escherichia coli. A total of 549 transcripts ended at intrinsic (rho-independent) terminators, but most of the other transcripts seemed to have variable ends. We found low-level antisense expression of most genes, and the 5' ends of these transcripts mapped to promoter-like sequences. Because antisense expression was reduced for highly expressed genes, we suspect that elongation of nonspecific antisense transcripts is suppressed by transcription of the sense strand. Finally, we combined the transcript results with comparative analysis and proteomics data to make 505 revisions to the original annotation of 3,531 proteins: we removed 255 (7.5%) proteins, changed 123 (3.6%) start codons, and added 127 (3.7%) proteins that had been missed. Tiling data had higher coverage than shotgun proteomics and hence led to most of the corrections, but many errors probably remain. Our data are available at http://genomics.lbl.gov/supplemental/DvHtranscripts2011/.
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