1
|
Andreani V, South EJ, Dunlop MJ. Generating information-dense promoter sequences with optimal string packing. PLoS Comput Biol 2024; 20:e1012276. [PMID: 39047028 PMCID: PMC11268586 DOI: 10.1371/journal.pcbi.1012276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Accepted: 06/25/2024] [Indexed: 07/27/2024] Open
Abstract
Dense arrangements of binding sites within nucleotide sequences can collectively influence downstream transcription rates or initiate biomolecular interactions. For example, natural promoter regions can harbor many overlapping transcription factor binding sites that influence the rate of transcription initiation. Despite the prevalence of overlapping binding sites in nature, rapid design of nucleotide sequences with many overlapping sites remains a challenge. Here, we show that this is an NP-hard problem, coined here as the nucleotide String Packing Problem (SPP). We then introduce a computational technique that efficiently assembles sets of DNA-protein binding sites into dense, contiguous stretches of double-stranded DNA. For the efficient design of nucleotide sequences spanning hundreds of base pairs, we reduce the SPP to an Orienteering Problem with integer distances, and then leverage modern integer linear programming solvers. Our method optimally packs sets of 20-100 binding sites into dense nucleotide arrays of 50-300 base pairs in 0.05-10 seconds. Unlike approximation algorithms or meta-heuristics, our approach finds provably optimal solutions. We demonstrate how our method can generate large sets of diverse sequences suitable for library generation, where the frequency of binding site usage across the returned sequences can be controlled by modulating the objective function. As an example, we then show how adding additional constraints, like the inclusion of sequence elements with fixed positions, allows for the design of bacterial promoters. The nucleotide string packing approach we present can accelerate the design of sequences with complex DNA-protein interactions. When used in combination with synthesis and high-throughput screening, this design strategy could help interrogate how complex binding site arrangements impact either gene expression or biomolecular mechanisms in varied cellular contexts.
Collapse
Affiliation(s)
- Virgile Andreani
- Biomedical Engineering Department, Boston University, Boston, Massachusetts, United States of America
- Biological Design Center, Boston University, Boston, Massachusetts, United States of America
| | - Eric J. South
- Biological Design Center, Boston University, Boston, Massachusetts, United States of America
- Molecular Biology, Cell Biology & Biochemistry Program, Boston University, Boston, Massachusetts, United States of America
| | - Mary J. Dunlop
- Biomedical Engineering Department, Boston University, Boston, Massachusetts, United States of America
- Biological Design Center, Boston University, Boston, Massachusetts, United States of America
- Molecular Biology, Cell Biology & Biochemistry Program, Boston University, Boston, Massachusetts, United States of America
| |
Collapse
|
2
|
Andreani V, South EJ, Dunlop MJ. Generating information-dense promoter sequences with optimal string packing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.01.565124. [PMID: 37961203 PMCID: PMC10635063 DOI: 10.1101/2023.11.01.565124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Dense arrangements of binding sites within nucleotide sequences can collectively influence downstream transcription rates or initiate biomolecular interactions. For example, natural promoter regions can harbor many overlapping transcription factor binding sites that influence the rate of transcription initiation. Despite the prevalence of overlapping binding sites in nature, rapid design of nucleotide sequences with many overlapping sites remains a challenge. Here, we show that this is an NP-hard problem, coined here as the nucleotide String Packing Problem (SPP). We then introduce a computational technique that efficiently assembles sets of DNA-protein binding sites into dense, contiguous stretches of double-stranded DNA. For the efficient design of nucleotide sequences spanning hundreds of base pairs, we reduce the SPP to an Orienteering Problem with integer distances, and then leverage modern integer linear programming solvers. Our method optimally packs libraries of 20-100 binding sites into dense nucleotide arrays of 50-300 base pairs in 0.05-10 seconds. Unlike approximation algorithms or meta-heuristics, our approach finds provably optimal solutions. We demonstrate how our method can generate large sets of diverse sequences suitable for library generation, where the frequency of binding site usage across the returned sequences can be controlled by modulating the objective function. As an example, we then show how adding additional constraints, like the inclusion of sequence elements with fixed positions, allows for the design of bacterial promoters. The nucleotide string packing approach we present can accelerate the design of sequences with complex DNA-protein interactions. When used in combination with synthesis and high-throughput screening, this design strategy could help interrogate how complex binding site arrangements impact either gene expression or biomolecular mechanisms in varied cellular contexts. Author Summary The way protein binding sites are arranged on DNA can control the regulation and transcription of downstream genes. Areas with a high concentration of binding sites can enable complex interplay between transcription factors, a feature that is exploited by natural promoters. However, designing synthetic promoters that contain dense arrangements of binding sites is a challenge. The task involves overlapping many binding sites, each typically about 10 nucleotides long, within a constrained sequence area, which becomes increasingly difficult as sequence length decreases, and binding site variety increases. We introduce an approach to design nucleotide sequences with optimally packed protein binding sites, which we call the nucleotide String Packing Problem (SPP). We show that the SPP can be solved efficiently using integer linear programming to identify the densest arrangements of binding sites for a specified sequence length. We show how adding additional constraints, like the inclusion of sequence elements with fixed positions, allows for the design of bacterial promoters. The presented approach enables the rapid design and study of nucleotide sequences with complex, dense binding site architectures.
Collapse
|
3
|
Pfotenhauer AC, Reuter DN, Clark M, Harbison SA, Schimel TM, Stewart CN, Lenaghan SC. Development of new binary expression systems for plant synthetic biology. PLANT CELL REPORTS 2023; 43:22. [PMID: 38150091 DOI: 10.1007/s00299-023-03100-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 10/10/2023] [Indexed: 12/28/2023]
Abstract
KEY MESSAGE A novel plant binary expression system was developed from the compactin biosynthetic pathway 27 of Penicillium citrinum ML-236B. The system achieved >fivefold activation of gene expression in 28 transgenic tobacco. A diverse and well-characterized genetic toolset is fundamental to achieve the overall goals of plant synthetic biology. To properly coordinate expression of a multigene pathway, this toolset should include binary systems that control gene expression at the level of transcription. In plants, few highly functional, orthogonal transcriptional regulators have been identified. Here, we describe the process of developing synthetic plant transcription factors using regulatory elements from the Penicillium citrinum ML-236B (compactin) pathway. This pathway contains several genes including mlcA and mlcC that are transcriptionally regulated in a dose-dependent manner by the activator mlcR. In Nicotiana benthamiana, we first expressed mlcR with several cognate synthetic promoters driving expression of GFP. Synthetic promoters contained operator sequences from the compactin gene cluster. Following identification of the most active synthetic promoter, the DNA-binding domain from mlcR was used to generate chimeric transcription factors containing variable activation domains, including QF from the Neurospora crassa Q-system. Activity was measured at both protein and RNA levels which correlated with an R2 value of 0.94. A synthetic transcription factor with a QF activation domain increased gene expression from its synthetic promoter up to sixfold in N. benthamiana. Two systems were characterized in transgenic tobacco plants. The QF-based plants maintained high expression in tobacco, increasing expression from the cognate synthetic promoter by fivefold. Transgenic plants and non-transgenic plants were morphologically indistinguishable. The framework of this study can easily be adopted for other putative transcription factors to continue improvement of the plant synthetic biology toolbox.
Collapse
Affiliation(s)
- Alexander C Pfotenhauer
- Center for Agricultural Synthetic Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - D Nikki Reuter
- Center for Agricultural Synthetic Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Mikayla Clark
- Center for Agricultural Synthetic Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Stacee A Harbison
- Center for Agricultural Synthetic Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Tayler M Schimel
- Center for Agricultural Synthetic Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - C Neal Stewart
- Center for Agricultural Synthetic Biology, University of Tennessee, Knoxville, TN, 37996, USA
- Department of Plant Sciences, The University of Tennessee, Knoxville, Knoxville, TN, USA
| | - Scott C Lenaghan
- Center for Agricultural Synthetic Biology, University of Tennessee, Knoxville, TN, 37996, USA.
- Department of Food Science, The University of Tennessee, Knoxville, Knoxville, TN, USA.
| |
Collapse
|
4
|
Amarelle V, Roldán DM, Fabiano E, Guazzaroni ME. Synthetic Biology Toolbox for Antarctic Pseudomonas sp. Strains: Toward a Psychrophilic Nonmodel Chassis for Function-Driven Metagenomics. ACS Synth Biol 2023; 12:722-734. [PMID: 36862944 DOI: 10.1021/acssynbio.2c00543] [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: 03/04/2023]
Abstract
One major limitation of function-driven metagenomics is the ability of the host to express the metagenomic DNA correctly. Differences in the transcriptional, translational, and post-translational machinery between the organism to which the DNA belongs and the host strain are all factors that influence the success of a functional screening. For this reason, the use of alternative hosts is an appropriate approach to favor the identification of enzymatic activities in function-driven metagenomics. To be implemented, appropriate tools should be designed to build the metagenomic libraries in those hosts. Moreover, discovery of new chassis and characterization of synthetic biology toolbox in nonmodel bacteria is an active field of research to expand the potential of these organisms in processes of industrial interest. Here, we assessed the suitability of two Antarctic psychrotolerant Pseudomonas strains as putative alternative hosts for function-driven metagenomics using pSEVA modular vectors as scaffold. We determined a set of synthetic biology tools suitable for these hosts and, as a proof of concept, we demonstrated their fitness for heterologous protein expression. These hosts represent a step forward for the prospection and identification of psychrophilic enzymes of biotechnological interest.
Collapse
Affiliation(s)
- Vanesa Amarelle
- Departamento de Bioquímica y Genómica Microbianas. Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo 11600, Uruguay
| | - Diego M Roldán
- Departamento de Bioquímica y Genómica Microbianas. Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo 11600, Uruguay
| | - Elena Fabiano
- Departamento de Bioquímica y Genómica Microbianas. Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo 11600, Uruguay
| | - María-Eugenia Guazzaroni
- Departamento de Biologia. FFCLRP, University of São Paulo, 14049-901 Ribeirão Preto, São Paulo, Brazil
| |
Collapse
|
5
|
Gomez-Hinostroza ES, Gurdo N, Alvan Vargas MVG, Nikel PI, Guazzaroni ME, Guaman LP, Castillo Cornejo DJ, Platero R, Barba-Ostria C. Current landscape and future directions of synthetic biology in South America. Front Bioeng Biotechnol 2023; 11:1069628. [PMID: 36845183 PMCID: PMC9950111 DOI: 10.3389/fbioe.2023.1069628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/30/2023] [Indexed: 02/12/2023] Open
Abstract
Synthetic biology (SynBio) is a rapidly advancing multidisciplinary field in which South American countries such as Chile, Argentina, and Brazil have made notable contributions and have established leadership positions in the region. In recent years, efforts have strengthened SynBio in the rest of the countries, and although progress is significant, growth has not matched that of the aforementioned countries. Initiatives such as iGEM and TECNOx have introduced students and researchers from various countries to the foundations of SynBio. Several factors have hindered progress in the field, including scarce funding from both public and private sources for synthetic biology projects, an underdeveloped biotech industry, and a lack of policies to promote bio-innovation. However, open science initiatives such as the DIY movement and OSHW have helped to alleviate some of these challenges. Similarly, the abundance of natural resources and biodiversity make South America an attractive location to invest in and develop SynBio projects.
Collapse
Affiliation(s)
- E. Sebastian Gomez-Hinostroza
- Laboratorio de Investigación en Citogenética y Biomoléculas de Anfibios (LICBA), Centro de Investigación para la Salud en América Latina (CISeAL), Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | - Nicolás Gurdo
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs Lyngby, Denmark
| | | | - Pablo I. Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs Lyngby, Denmark
| | | | - Linda P. Guaman
- Centro de Investigación Biomédica (CENBIO), Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | | | - Raúl Platero
- Laboratorio de Microbiología Ambiental, Departamento de Bioquímica y Genómica Microbianas, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Carlos Barba-Ostria
- Escuela de Medicina, Colegio de Ciencias de la Salud Quito, Universidad San Francisco de Quito USFQ, Quito, Ecuador,Instituto de Microbiología, Universidad San Francisco de Quito USFQ, Quito, Ecuador,*Correspondence: Carlos Barba-Ostria,
| |
Collapse
|
6
|
Tietze L, Lale R. Importance of the 5' regulatory region to bacterial synthetic biology applications. Microb Biotechnol 2021; 14:2291-2315. [PMID: 34171170 PMCID: PMC8601185 DOI: 10.1111/1751-7915.13868] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 01/02/2023] Open
Abstract
The field of synthetic biology is evolving at a fast pace. It is advancing beyond single-gene alterations in single hosts to the logical design of complex circuits and the development of integrated synthetic genomes. Recent breakthroughs in deep learning, which is increasingly used in de novo assembly of DNA components with predictable effects, are also aiding the discipline. Despite advances in computing, the field is still reliant on the availability of pre-characterized DNA parts, whether natural or synthetic, to regulate gene expression in bacteria and make valuable compounds. In this review, we discuss the different bacterial synthetic biology methodologies employed in the creation of 5' regulatory regions - promoters, untranslated regions and 5'-end of coding sequences. We summarize methodologies and discuss their significance for each of the functional DNA components, and highlight the key advances made in bacterial engineering by concentrating on their flaws and strengths. We end the review by outlining the issues that the discipline may face in the near future.
Collapse
Affiliation(s)
- Lisa Tietze
- PhotoSynLabDepartment of BiotechnologyFaculty of Natural SciencesNorwegian University of Science and TechnologyTrondheimN‐7491Norway
| | - Rahmi Lale
- PhotoSynLabDepartment of BiotechnologyFaculty of Natural SciencesNorwegian University of Science and TechnologyTrondheimN‐7491Norway
| |
Collapse
|
7
|
Wang Y, Wang H, Wei L, Li S, Liu L, Wang X. Synthetic promoter design in Escherichia coli based on a deep generative network. Nucleic Acids Res 2020; 48:6403-6412. [PMID: 32424410 PMCID: PMC7337522 DOI: 10.1093/nar/gkaa325] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 04/05/2020] [Accepted: 04/22/2020] [Indexed: 01/11/2023] Open
Abstract
Promoter design remains one of the most important considerations in metabolic engineering and synthetic biology applications. Theoretically, there are 450 possible sequences for a 50-nt promoter, of which naturally occurring promoters make up only a small subset. To explore the vast number of potential sequences, we report a novel AI-based framework for de novo promoter design in Escherichia coli. The model, which was guided by sequence features learned from natural promoters, could capture interactions between nucleotides at different positions and design novel synthetic promoters in silico. We combined a deep generative model that guides the search for artificial sequences with a predictive model to preselect the most promising promoters. The AI-designed promoters were optimized based on the promoter activity in E. coli and the predictive model. After two rounds of optimization, up to 70.8% of the AI-designed promoters were experimentally demonstrated to be functional, and few of them shared significant sequence similarity with the E. coli genome. Our work provided an end-to-end approach to the de novo design of novel promoter elements, indicating the potential to apply deep learning methods to de novo genetic element design.
Collapse
Affiliation(s)
- Ye Wang
- Ministry of Education Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Bioinformatics Division, Beijing National Research Center for Information Science and Technology; Department of Automation, Tsinghua University, Beijing 100084, China
| | - Haochen Wang
- Ministry of Education Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Bioinformatics Division, Beijing National Research Center for Information Science and Technology; Department of Automation, Tsinghua University, Beijing 100084, China
| | - Lei Wei
- Ministry of Education Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Bioinformatics Division, Beijing National Research Center for Information Science and Technology; Department of Automation, Tsinghua University, Beijing 100084, China
| | - Shuailin Li
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Liyang Liu
- Ministry of Education Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Bioinformatics Division, Beijing National Research Center for Information Science and Technology; Department of Automation, Tsinghua University, Beijing 100084, China
| | - Xiaowo Wang
- Ministry of Education Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Bioinformatics Division, Beijing National Research Center for Information Science and Technology; Department of Automation, Tsinghua University, Beijing 100084, China
| |
Collapse
|
8
|
Tsigkinopoulou A, Takano E, Breitling R. Unravelling the γ-butyrolactone network in Streptomyces coelicolor by computational ensemble modelling. PLoS Comput Biol 2020; 16:e1008039. [PMID: 32649676 PMCID: PMC7384680 DOI: 10.1371/journal.pcbi.1008039] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 07/27/2020] [Accepted: 06/10/2020] [Indexed: 02/06/2023] Open
Abstract
Antibiotic production is coordinated in the Streptomyces coelicolor population through the use of diffusible signaling molecules of the γ-butyrolactone (GBL) family. The GBL regulatory system involves a small, and not completely defined two-gene network which governs a potentially bi-stable switch between the “on” and “off” states of antibiotic production. The use of this circuit as a tool for synthetic biology has been hampered by a lack of mechanistic understanding of its functionality. We here present the creation and analysis of a versatile and adaptable ensemble model of the Streptomyces GBL system (detailed information on all model mechanisms and parameters is documented in http://www.systemsbiology.ls.manchester.ac.uk/wiki/index.php/Main_Page). We use the model to explore a range of previously proposed mechanistic hypotheses, including transcriptional interference, antisense RNA interactions between the mRNAs of the two genes, and various alternative regulatory activities. Our results suggest that transcriptional interference alone is not sufficient to explain the system’s behavior. Instead, antisense RNA interactions seem to be the system's driving force, combined with an aggressive scbR promoter. The computational model can be used to further challenge and refine our understanding of the system’s activity and guide future experimentation. Streptomyces species are Gram-positive soil-dwelling bacteria, which are known as a prolific source of secondary metabolites, such as antibiotics. Antibiotic production is coordinated in the bacterial population through the use of diffusible signalling molecules of the γ-butyrolactone (GBL) family. The GBL regulatory system involves a small, yet complex two-gene network, the mechanism of which has not yet been completely defined. The complete elucidation of this system could potentially lead to the ability to design reliable and sensitive engineered cellular switches. We therefore designed a versatile model of the GBL system in order to investigate the feasibility of various hypothesized mechanisms. The ensemble modelling analysis that we performed revealed that antisense RNA interactions seem to be the system’s driving force, together with an aggressive scbR promoter. Transcriptional interference is also significant; however, it is not sufficient to explain the system’s behavior by itself. Finally, the model indicates key experiments, which could completely elucidate the role of the system and the interactions of its components and potentially lead to the design of reliable and sensitive systems with significant applications as orthologous regulatory circuits in synthetic biology and biotechnology.
Collapse
Affiliation(s)
- Areti Tsigkinopoulou
- DTU Biosustain, Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
- Manchester Institute of Biotechnology, School of Natural Sciences, University of Manchester, Manchester, United Kingdom
| | - Eriko Takano
- Manchester Institute of Biotechnology, School of Natural Sciences, University of Manchester, Manchester, United Kingdom
| | - Rainer Breitling
- Manchester Institute of Biotechnology, School of Natural Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail:
| |
Collapse
|
9
|
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.
Collapse
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
| |
Collapse
|
10
|
Monteiro LMO, Arruda LM, Sanches-Medeiros A, Martins-Santana L, Alves LDF, Defelipe L, Turjanski AG, Guazzaroni ME, de Lorenzo V, Silva-Rocha R. Reverse Engineering of an Aspirin-Responsive Transcriptional Regulator in Escherichia coli. ACS Synth Biol 2019; 8:1890-1900. [PMID: 31362496 DOI: 10.1021/acssynbio.9b00191] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Bacterial transcription factors (TFs) are key devices for the engineering of complex circuits in many biotechnological applications, yet there are few well-characterized inducer-responsive TFs that could be used in the context of an animal or human host. We have deciphered the inducer recognition mechanism of two AraC/XylS regulators from Pseudomonas putida (BenR and XylS) for creating a novel expression system responsive to acetyl salicylate (i.e., aspirin). Using protein homology modeling and molecular docking with the cognate inducer benzoate and a suite of chemical analogues, we identified the conserved binding pocket of BenR and XylS. By means of site-directed mutagenesis, we identified a single amino acid position required for efficient inducer recognition and transcriptional activation. Whereas this modification in BenR abolishes protein activity, in XylS, it increases the response to several inducers, including acetyl salicylic acid, to levels close to those achieved by the canonical inducer. Moreover, by constructing chimeric proteins with swapped N-terminal domains, we created novel regulators with mixed promoter and inducer recognition profiles. As a result, a collection of engineered TFs was generated with an enhanced response to benzoate, 3-methylbenzoate, 2-methylbenzoate, 4-methylbenzoate, salicylic acid, aspirin, and acetylsalicylic acid molecules for eliciting gene expression in E. coli.
Collapse
Affiliation(s)
| | - Letı́cia Magalhães Arruda
- Cell and Molecular Biology Department, FMRP − University of São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil
| | - Ananda Sanches-Medeiros
- Cell and Molecular Biology Department, FMRP − University of São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil
| | - Leonardo Martins-Santana
- Cell and Molecular Biology Department, FMRP − University of São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil
| | - Luana de Fátima Alves
- Biology Department, FFCLRP − University of São Paulo, Ribeirão Preto, São Paulo 14040-901, Brazil
| | - Lucas Defelipe
- Departamento de Quı́mica Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
- IQUIBICEN/UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
| | - Adrian Gustavo Turjanski
- Departamento de Quı́mica Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
- IQUIBICEN/UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
| | | | - Vı́ctor de Lorenzo
- Systems Biology Program, National Center of Biotechnology − CSIC, Madrid 28049, Spain
| | - Rafael Silva-Rocha
- Cell and Molecular Biology Department, FMRP − University of São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil
| |
Collapse
|
11
|
de Frias UA, Pereira GKB, Guazzaroni ME, Silva-Rocha R. Boosting Secondary Metabolite Production and Discovery through the Engineering of Novel Microbial Biosensors. BIOMED RESEARCH INTERNATIONAL 2018; 2018:7021826. [PMID: 30079350 PMCID: PMC6069586 DOI: 10.1155/2018/7021826] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 02/11/2018] [Indexed: 01/05/2023]
Abstract
Bacteria are a source of a large number of secondary metabolites with several biomedical and biotechnological applications. In recent years, there has been tremendous progress in the development of novel synthetic biology approaches both to increase the production rate of secondary metabolites of interest in native producers and to mine and reconstruct novel biosynthetic gene clusters in heterologous hosts. Here, we present the recent advances toward the engineering of novel microbial biosensors to detect the synthesis of secondary metabolites in bacteria and in the development of synthetic promoters and expression systems aiming at the construction of microbial cell factories for the production of these compounds. We place special focus on the potential of Gram-negative bacteria as a source of biosynthetic gene clusters and hosts for pathway assembly, on the construction and characterization of novel promoters for native hosts, and on the use of computer-aided design of novel pathways and expression systems for secondary metabolite production. Finally, we discuss some of the potentials and limitations of the approaches that are currently being developed and we highlight new directions that could be addressed in the field.
Collapse
Affiliation(s)
| | | | - María-Eugenia Guazzaroni
- Faculty of Philosophy, Science and Letters of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Rafael Silva-Rocha
- Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| |
Collapse
|
12
|
Westmann CA, Alves LDF, Silva-Rocha R, Guazzaroni ME. Mining Novel Constitutive Promoter Elements in Soil Metagenomic Libraries in Escherichia coli. Front Microbiol 2018; 9:1344. [PMID: 29973927 PMCID: PMC6019500 DOI: 10.3389/fmicb.2018.01344] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 05/31/2018] [Indexed: 11/13/2022] Open
Abstract
Although functional metagenomics has been widely employed for the discovery of genes relevant to biotechnology and biomedicine, its potential for assessing the diversity of transcriptional regulatory elements of microbial communities has remained poorly explored. Here, we experimentally mined novel constitutive promoter sequences in metagenomic libraries by combining a bi-directional reporter vector, high-throughput fluorescence assays and predictive computational methods. Through the expression profiling of fluorescent clones from two independent soil sample libraries, we have analyzed the regulatory dynamics of 260 clones with candidate promoters as a set of active metagenomic promoters in the host Escherichia coli. Through an in-depth analysis of selected clones, we were able to further explore the architecture of metagenomic fragments and to report the presence of multiple promoters per fragment with a dominant promoter driving the expression profile. These approaches resulted in the identification of 33 novel active promoters from metagenomic DNA originated from very diverse phylogenetic groups. The in silico and in vivo analysis of these individual promoters allowed the generation of a constitutive promoter consensus for exogenous sequences recognizable by E. coli in metagenomic studies. The results presented here demonstrates the potential of functional metagenomics for exploring environmental bacterial communities as a source of novel regulatory genetic parts to expand the toolbox for microbial engineering.
Collapse
Affiliation(s)
- Cauã A Westmann
- Department of Cellular and Molecular Biology, FMRP, University of São Paulo, Ribeirão Preto, Brazil
| | - Luana de Fátima Alves
- Department of Biology, FFCLRP, University of São Paulo, Ribeirão Preto, Brazil.,Department of Biochemistry, FMRP, University of São Paulo, Ribeirão Preto, Brazil
| | - Rafael Silva-Rocha
- Department of Cellular and Molecular Biology, FMRP, University of São Paulo, Ribeirão Preto, Brazil
| | | |
Collapse
|
13
|
Engineering Complexity in Bacterial Regulatory Circuits for Biotechnological Applications. mSystems 2018; 3:mSystems00151-17. [PMID: 29657966 PMCID: PMC5895878 DOI: 10.1128/msystems.00151-17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/14/2018] [Indexed: 01/29/2023] Open
Abstract
Engineering microbial systems allows the generation of new technologies having significant impact in the biotechnological industry and on human health. In the past few years, several synthetic biology approaches have been implemented in bacteria to allow precise engineering of novel regulatory circuits for several applications. Engineering microbial systems allows the generation of new technologies having significant impact in the biotechnological industry and on human health. In the past few years, several synthetic biology approaches have been implemented in bacteria to allow precise engineering of novel regulatory circuits for several applications. The advent of high-throughput technologies and clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-based DNA editing techniques have been pivotal in this process. Yet, despite the tremendous advances experienced recently, there are still a number of bottlenecks that need to be overcome in order to generate high-performance redesigned living machines, and the use of novel computer-aided approaches would be essential for this task. In this perspective, we discuss some of the main advances in the field of microbial engineering and the new technologies and approaches that should allow the construction of on demand synthetic microbial factories through the redesign of regulatory complexity.
Collapse
|
14
|
Calibrating Transcriptional Activity Using Constitutive Synthetic Promoters in Mutants for Global Regulators in Escherichia coli. Int J Genomics 2018; 2018:9235605. [PMID: 29750145 PMCID: PMC5884034 DOI: 10.1155/2018/9235605] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 01/30/2018] [Indexed: 11/23/2022] Open
Abstract
The engineering of synthetic circuits in cells relies on the use of well-characterized biological parts that would perform predicted functions under the situation considered, and many efforts have been taken to set biological standards that could define the basic features of these parts. However, since most synthetic biology projects usually require a particular cellular chassis and set of growth conditions, defining standards in the field is not a simple task as gene expression measurements could be affected severely by genetic background and culture conditions. In this study, we addressed promoter parameterization in bacteria in different genetic backgrounds and growth conditions. We found that a small set of constitutive promoters of different strengths controlling a short-lived GFP reporter placed in a low-copy number plasmid produces remarkably reproducible results that allow for the calibration of promoter activity over different genetic backgrounds and physiological conditions, thus providing a simple way to set standards of promoter activity in bacteria. Based on these results, we proposed the utilization of synthetic constitutive promoters as tools for calibration for the standardization of biological parts, in a way similar to the use of DNA and protein ladders in molecular biology as references for comparison with samples of interest.
Collapse
|
15
|
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.
Collapse
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
| |
Collapse
|
16
|
Amores GR, de Las Heras A, Sanches-Medeiros A, Elfick A, Silva-Rocha R. Systematic identification of novel regulatory interactions controlling biofilm formation in the bacterium Escherichia coli. Sci Rep 2017; 7:16768. [PMID: 29196655 PMCID: PMC5711951 DOI: 10.1038/s41598-017-17114-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/22/2017] [Indexed: 01/11/2023] Open
Abstract
Here, we investigated novel interactions of three global regulators of the network that controls biofilm formation in the model bacterium Escherichia coli using computational network analysis, an in vivo reporter assay and physiological validation experiments. We were able to map critical nodes that govern planktonic to biofilm transition and identify 8 new regulatory interactions for CRP, IHF or Fis responsible for the control of the promoters of rpoS, rpoE, flhD, fliA, csgD and yeaJ. Additionally, an in vivo promoter reporter assay and motility analysis revealed a key role for IHF as a repressor of cell motility through the control of FliA sigma factor expression. This investigation of first stage and mature biofilm formation indicates that biofilm structure is strongly affected by IHF and Fis, while CRP seems to provide a fine-tuning mechanism. Taken together, the analysis presented here shows the utility of combining computational and experimental approaches to generate a deeper understanding of the biofilm formation process in bacteria.
Collapse
Affiliation(s)
| | - Aitor de Las Heras
- Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, UK
- SynthSys Research Centre, University of Edinburgh, Edinburgh, UK
| | | | - Alistair Elfick
- Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, UK
- SynthSys Research Centre, University of Edinburgh, Edinburgh, UK
| | | |
Collapse
|
17
|
Bordoy AE, Varanasi US, Courtney CM, Chatterjee A. Transcriptional Interference in Convergent Promoters as a Means for Tunable Gene Expression. ACS Synth Biol 2016; 5:1331-1341. [PMID: 27346626 DOI: 10.1021/acssynbio.5b00223] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
An important goal of synthetic biology involves the extension and standardization of novel biological elements for applications in medicine and biotechnology. Transcriptional interference, occurring in sets of convergent promoters, offers a promising mechanism for building elements for the design of tunable gene regulation. Here, we investigate the transcriptional interference mechanisms of antisense roadblock and RNA polymerase traffic in a set of convergent promoters as novel modules for synthetic biology. We show examples of elements, including antisense roadblock, relative promoter strengths, interpromoter distance, and sequence content that can be tuned to give rise to repressive as well as cooperative behaviors, therefore resulting in distinct gene expression patterns. Our approach will be useful toward engineering new biological devices and will bring new insights to naturally occurring cis-antisense systems. Therefore, we are reporting a new biological tool that can be used for synthetic biology.
Collapse
Affiliation(s)
- Antoni E. Bordoy
- Department of Chemical and Biological Engineering, ‡BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Avenue, UCB 596, Boulder, Colorado 80303, United States
| | - Usha S. Varanasi
- Department of Chemical and Biological Engineering, ‡BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Avenue, UCB 596, Boulder, Colorado 80303, United States
| | - Colleen M. Courtney
- Department of Chemical and Biological Engineering, ‡BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Avenue, UCB 596, Boulder, Colorado 80303, United States
| | - Anushree Chatterjee
- Department of Chemical and Biological Engineering, ‡BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Avenue, UCB 596, Boulder, Colorado 80303, United States
| |
Collapse
|
18
|
Arruda LM, Monteiro LMO, Silva-Rocha R. The Chromobacterium violaceum ArsR Arsenite Repressor Exerts Tighter Control on Its Cognate Promoter Than the Escherichia coli System. Front Microbiol 2016; 7:1851. [PMID: 27917165 PMCID: PMC5116461 DOI: 10.3389/fmicb.2016.01851] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/03/2016] [Indexed: 11/13/2022] Open
Abstract
Environmental bacteria are endowed with several regulatory systems that have potential applications in biotechnology. In this report, we characterize the arsenic biosensing features of the ars response system from Chromobacterium violaceum in the heterologous host Escherichia coli. We show that the native Pars/arsR system of C. violaceum outperforms the chromosomal ars copy of E. coli when exposed to micromolar concentrations of arsenite. To understand the molecular basis of this phenomenon, we analyzed the interaction between ArsR regulators and their promoter target sites as well as induction of the system at saturating concentrations of the regulators. In vivo titration experiments indicate that ArsR from C. violaceum has stronger binding affinity for its target promoter than the regulator from E. coli does. Additionally, arsenite induction experiments at saturating regulator concentration demonstrates that although the Pars/arsR system from E. coli displays a gradual response to increasing concentration of the inducer, the system from C. violaceum has a steeper response with a stronger promoter induction after a given arsenite threshold. Taken together, these data demonstrate the characterization of a novel arsenic response element from an environmental bacterium with potentially enhanced performance that could be further explored for the construction of an arsenic biosensor.
Collapse
Affiliation(s)
- Letícia M Arruda
- Systems and Synthetic Biology Lab, Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil
| | - Lummy M O Monteiro
- Systems and Synthetic Biology Lab, Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil
| | - Rafael Silva-Rocha
- Systems and Synthetic Biology Lab, Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil
| |
Collapse
|
19
|
Abstract
Characterization of gene expression is a central tenet of the synthetic biology design cycle. Sometimes it requires high-throughput approaches that allow quantification of the gene expression of different elements in diverse conditions. Recently, several large-scale studies have highlighted the importance of posttranscriptional regulation mechanisms and their impact on correlations between mRNA and protein abundance. Here, we introduce Edwin, a robotic workstation that enables the automated propagation of microbial cells and the dynamic characterization of gene expression. We developed an automated procedure that integrates customized RNA extraction and analysis into the typical high-throughput characterization of reporter gene expression. To test the system, we engineered Escherichia coli strains carrying different promoter/ gfp fusions. We validated Edwin's abilities: (1) preparation of custom cultures of microbial cells and (2) dynamic quantification of fluorescence signal and bacterial growth and simultaneous RNA extraction and analysis at different time points. We confirmed that RNA obtained during this automated process was suitable for use in qPCR analysis. Our results established that Edwin is a powerful platform for the automated analysis of microbial gene expression at the protein and RNA level. This platform could be used in a high-throughput manner to characterize not only natural regulatory elements but also synthetic ones.
Collapse
Affiliation(s)
- Aitor de Las Heras
- 1 Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, UK.,2 SynthSys Research Centre, University of Edinburgh, Edinburgh, UK
| | - Weike Xiao
- 1 Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, UK
| | - Vlastimil Sren
- 1 Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, UK
| | - Alistair Elfick
- 1 Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, UK.,2 SynthSys Research Centre, University of Edinburgh, Edinburgh, UK
| |
Collapse
|
20
|
|
21
|
Amores GR, Guazzaroni ME, Silva-Rocha R. Engineering Synthetic cis-Regulatory Elements for Simultaneous Recognition of Three Transcriptional Factors in Bacteria. ACS Synth Biol 2015; 4:1287-94. [PMID: 26305598 DOI: 10.1021/acssynbio.5b00098] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recognition of cis-regulatory elements by transcription factors (TF) at target promoters is crucial to gene regulation in bacteria. In this process, binding of TFs to their cognate sequences depends on a set of physical interactions between these proteins and specific nucleotides in the operator region. Previously, we showed that in silico optimization algorithms are able to generate short sequences that are recognized by two different TFs of Escherichia coli, namely, CRP and IHF, thus generating an AND logic gate. Here, we expanded this approach in order to engineer DNA sequences that can be simultaneously recognized by three unrelated TFs (CRP, IHF, and Fis). Using in silico optimization and experimental validation strategies, we were able to obtain a candidate promoter (Plac-CFI1) regulated by only two TFs with an AND logic, thus demonstrating a limitation in the design. Subsequently, we modified the algorithm to allow the optimization of extended sequences, and were able to design two synthetic promoters (PCFI20-1 and PCFI22-5) that were functional in vivo. Expression assays in E. coli mutant strains for each TF revealed that while CRP positively regulates the promoter activities, IHF and Fis are strong repressors of both the promoter variants. Taken together, our results demonstrate the potential of in silico strategies in bacterial synthetic promoter engineering. Furthermore, the study also shows how small modifications in cis-regulatory elements can drastically affect the final logic of the resulting promoter.
Collapse
Affiliation(s)
| | | | - Rafael Silva-Rocha
- FMRP, University of São Paulo, Ribeirão
Preto, São Paulo 05508-020, Brazil
| |
Collapse
|