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Gahlot DK, Taheri N, MacIntyre S. Diversity in Genetic Regulation of Bacterial Fimbriae Assembled by the Chaperone Usher Pathway. Int J Mol Sci 2022; 24:ijms24010161. [PMID: 36613605 PMCID: PMC9820224 DOI: 10.3390/ijms24010161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 12/24/2022] Open
Abstract
Bacteria express different types of hair-like proteinaceous appendages on their cell surface known as pili or fimbriae. These filamentous structures are primarily involved in the adherence of bacteria to both abiotic and biotic surfaces for biofilm formation and/or virulence of non-pathogenic and pathogenic bacteria. In pathogenic bacteria, especially Gram-negative bacteria, fimbriae play a key role in bacteria-host interactions which are critical for bacterial invasion and infection. Fimbriae assembled by the Chaperone Usher pathway (CUP) are widespread within the Enterobacteriaceae, and their expression is tightly regulated by specific environmental stimuli. Genes essential for expression of CUP fimbriae are organised in small blocks/clusters, which are often located in proximity to other virulence genes on a pathogenicity island. Since these surface appendages play a crucial role in bacterial virulence, they have potential to be harnessed in vaccine development. This review covers the regulation of expression of CUP-assembled fimbriae in Gram-negative bacteria and uses selected examples to demonstrate both dedicated and global regulatory mechanisms.
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Affiliation(s)
- Dharmender K. Gahlot
- School of Biological Sciences, University of Reading, Reading RG6 6EX, UK
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, 901 87 Umeå, Sweden
- Correspondence: (D.K.G.); (S.M.)
| | - Nayyer Taheri
- APC Microbiome Institute, University College Cork, T12 K8AF Cork, Ireland
| | - Sheila MacIntyre
- School of Biological Sciences, University of Reading, Reading RG6 6EX, UK
- Correspondence: (D.K.G.); (S.M.)
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Optimised Heterologous Expression and Functional Analysis of the Yersinia pestis F1-Capsular Antigen Regulator Caf1R. Int J Mol Sci 2021; 22:ijms22189805. [PMID: 34575967 PMCID: PMC8470410 DOI: 10.3390/ijms22189805] [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: 08/02/2021] [Revised: 09/02/2021] [Accepted: 09/06/2021] [Indexed: 12/14/2022] Open
Abstract
The bacterial pathogen, Yersinia pestis, has caused three historic pandemics and continues to cause small outbreaks worldwide. During infection, Y. pestis assembles a capsule-like protective coat of thin fibres of Caf1 subunits. This F1 capsular antigen has attracted much attention due to its clinical value in plague diagnostics and anti-plague vaccine development. Expression of F1 is tightly regulated by a transcriptional activator, Caf1R, of the AraC/XylS family, proteins notoriously prone to aggregation. Here, we have optimised the recombinant expression of soluble Caf1R. Expression from the native and synthetic codon-optimised caf1R cloned in three different expression plasmids was examined in a library of E. coli host strains. The functionality of His-tagged Caf1R was demonstrated in vivo, but insolubility was a problem with overproduction. High levels of soluble MBP-Caf1R were produced from codon optimised caf1R. Transcriptional-lacZ reporter fusions defined the PM promoter and Caf1R binding site responsible for transcription of the cafMA1 operon. Use of the identified Caf1R binding caf DNA sequence in an electrophoretic mobility shift assay (EMSA) confirmed correct folding and functionality of the Caf1R DNA-binding domain in recombinant MBP-Caf1R. Availability of functional recombinant Caf1R will be a valuable tool to elucidate control of expression of F1 and Caf1R-regulated pathophysiology of Y. pestis.
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Cortés-Avalos D, Martínez-Pérez N, Ortiz-Moncada MA, Juárez-González A, Baños-Vargas AA, Estrada-de Los Santos P, Pérez-Rueda E, Ibarra JA. An update of the unceasingly growing and diverse AraC/XylS family of transcriptional activators. FEMS Microbiol Rev 2021; 45:6219864. [PMID: 33837749 DOI: 10.1093/femsre/fuab020] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 03/31/2021] [Indexed: 01/09/2023] Open
Abstract
Transcriptional factors play an important role in gene regulation in all organisms, especially in Bacteria. Here special emphasis is placed in the AraC/XylS family of transcriptional regulators. This is one of the most abundant as many predicted members have been identified and more members are added because more bacterial genomes are sequenced. Given the way more experimental evidence has mounded in the past decades, we decided to update the information about this captivating family of proteins. Using bioinformatics tools on all the data available for experimentally characterized members of this family, we found that many members that display a similar functional classification can be clustered together and in some cases they have a similar regulatory scheme. A proposal for grouping these proteins is also discussed. Additionally, an analysis of surveyed proteins in bacterial genomes is presented. Altogether, the current review presents a panoramic view into this family and we hope it helps to stimulate future research in the field.
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Affiliation(s)
- Daniel Cortés-Avalos
- Laboratorio de Genética Microbiana, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México
| | - Noemy Martínez-Pérez
- Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad Nacional Autónoma de México, Unidad Académica Yucatán, Mérida, Yucatán, México
| | - Mario A Ortiz-Moncada
- Laboratorio de Genética Microbiana, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México
| | - Aylin Juárez-González
- Laboratorio de Genética Microbiana, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México
| | - Arturo A Baños-Vargas
- Laboratorio de Genética Microbiana, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México
| | - Paulina Estrada-de Los Santos
- Laboratorio de Biotecnología Microbiana, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México
| | - Ernesto Pérez-Rueda
- Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad Nacional Autónoma de México, Unidad Académica Yucatán, Mérida, Yucatán, México.,Facultad de Ciencias, Centro de Genómica y Bioinformática, Universidad Mayor, Santiago, Chile
| | - J Antonio Ibarra
- Laboratorio de Genética Microbiana, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México
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A Novel Two-Component System, XygS/XygR, Positively Regulates Xyloglucan Degradation, Import, and Catabolism in Ruminiclostridium cellulolyticum. Appl Environ Microbiol 2020; 86:AEM.01357-20. [PMID: 32769189 DOI: 10.1128/aem.01357-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 07/31/2020] [Indexed: 12/27/2022] Open
Abstract
Cellulolytic microorganisms play a key role in the global carbon cycle by decomposing structurally diverse plant biopolymers from dead plant matter. These microorganisms, in particular anaerobes such as Ruminiclostridium cellulolyticum that are capable of degrading and catabolizing several different polysaccharides, require a fine-tuned regulation of the biosynthesis of their polysaccharide-degrading enzymes. In this study, we present a bacterial regulatory system involved in the regulation of genes enabling the metabolism of the ubiquitous plant polysaccharide xyloglucan. The characterization of R. cellulolyticum knockout mutants suggests that the response regulator XygR and its cognate histidine kinase XygS are essential for growth on xyloglucan. Using in vitro and in vivo analyses, we show that XygR binds to the intergenic region and activates the expression of two polycistronic transcriptional units encoding an ABC transporter dedicated to the uptake of xyloglucan oligosaccharides and the two-component system itself together with three intracellular glycoside hydrolases responsible for the sequential intracellular degradation of the imported oligosaccharides into mono- and disaccharides. Interestingly, XygR also upregulates the expression of a distant gene coding for the most active extracellular cellulosomal xyloglucanase of R. cellulolyticum by binding to the upstream intergenic region.IMPORTANCE Ruminiclostridium cellulolyticum is a Gram-positive, mesophilic, anaerobic, cellulolytic, and hemicellulolytic bacterium. The last property qualifies this species as a model species for the study of hemicellulose degradation, import of degradation products, and overall regulation of these phenomena. In this study, we focus on the regulation of xyloglucan dextrin import and intracellular degradation and show that the two components of the two-component regulation system XygSR are essential for growth on xyloglucan and that the response regulator XygR regulates the transcription of genes involved in the extracellular degradation of the polysaccharide, the import of degradation products, and their intracellular degradation.
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Liew KJ, Bruce NC, Sani RK, Chong CS, Yaakop AS, Shamsir MS, Goh KM. Global Transcriptomic Responses of Roseithermus sacchariphilus Strain RA in Media Supplemented with Beechwood Xylan. Microorganisms 2020; 8:E976. [PMID: 32610703 PMCID: PMC7409140 DOI: 10.3390/microorganisms8070976] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/23/2020] [Accepted: 06/27/2020] [Indexed: 11/17/2022] Open
Abstract
The majority of the members in order Rhodothermales are underexplored prokaryotic extremophiles. Roseithermus, a new genus within Rhodothermales, was first described in 2019. Roseithermus sacchariphilus is the only species in this genus. The current report aims to evaluate the transcriptomic responses of R. sacchariphilus strain RA when cultivated on beechwood xylan. Strain RA doubled its growth in Marine Broth (MB) containing xylan compared to Marine Broth (MB) alone. Strain RA harbors 54 potential glycosyl hydrolases (GHs) that are affiliated with 30 families, including cellulases (families GH 3, 5, 9, and 44) and hemicellulases (GH 2, 10, 16, 29, 31,43, 51, 53, 67, 78, 92, 106, 113, 130, and 154). The majority of these GHs were upregulated when the cells were grown in MB containing xylan medium and enzymatic activities for xylanase, endoglucanase, β-xylosidase, and β-glucosidase were elevated. Interestingly, with the introduction of xylan, five out of six cellulolytic genes were upregulated. Furthermore, approximately 1122 genes equivalent to one-third of the total genes for strain RA were upregulated. These upregulated genes were mostly involved in transportation, chemotaxis, and membrane components synthesis.
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Affiliation(s)
- Kok Jun Liew
- Faculty of Science, Universiti Teknologi Malaysia, Johor 81310, Malaysia; (K.J.L.); (C.S.C.); (M.S.S.)
| | - Neil C. Bruce
- Centre for Novel Agricultural Products, Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK;
| | - Rajesh Kumar Sani
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA;
| | - Chun Shiong Chong
- Faculty of Science, Universiti Teknologi Malaysia, Johor 81310, Malaysia; (K.J.L.); (C.S.C.); (M.S.S.)
| | - Amira Suriaty Yaakop
- School of Biological Sciences, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia;
| | - Mohd Shahir Shamsir
- Faculty of Science, Universiti Teknologi Malaysia, Johor 81310, Malaysia; (K.J.L.); (C.S.C.); (M.S.S.)
- Faculty of Applied Sciences and Technology, Universiti Tun Hussein Onn Malaysia, Pagoh Higher Education Hub, Johor 84600, Malaysia
| | - Kian Mau Goh
- Faculty of Science, Universiti Teknologi Malaysia, Johor 81310, Malaysia; (K.J.L.); (C.S.C.); (M.S.S.)
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Chhiba-Govindjee VP, van der Westhuyzen CW, Bode ML, Brady D. Bacterial nitrilases and their regulation. Appl Microbiol Biotechnol 2019; 103:4679-4692. [DOI: 10.1007/s00253-019-09776-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 12/25/2022]
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Xu T, Wu Y, Lin Z, Bertram R, Götz F, Zhang Y, Qu D. Identification of Genes Controlled by the Essential YycFG Two-Component System Reveals a Role for Biofilm Modulation in Staphylococcus epidermidis. Front Microbiol 2017; 8:724. [PMID: 28491057 PMCID: PMC5405149 DOI: 10.3389/fmicb.2017.00724] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/07/2017] [Indexed: 01/11/2023] Open
Abstract
Biofilms play a crucial role in the pathogenicity of Staphylococcus epidermidis, while little is known about whether the essential YycFG two-component signal transduction system (TCS) is involved in biofilm formation. We used antisense RNA (asRNA) to silence the yycFG TCS in order to study its regulatory functions in S. epidermidis. Strain 1457 expressing asRNAyycF exhibited a significant delay (~4–5 h) in entry to log phase, which was partially complemented by overexpressing ssaA. The expression of asRNAyycF and asRNAyycG resulted in a 68 and 50% decrease in biofilm formation at 6 h, respectively, while they had no significant inhibitory effect on 12 h biofilm formation. The expression of asRNAyycF led to a ~5-fold increase in polysaccharide intercellular adhesion (PIA) production, but it did not affect the expression of accumulation-associated protein (Aap) or the release of extracellular DNA. Consistently, quantitative real-time PCR showed that silencing yycF resulted in an increased transcription of biofilm-related genes, including icaA, arlR, sarA, sarX, and sbp. An in silico search of the YycF regulon for the conserved YycF recognition pattern and a modified motif in S. epidermidis, along with additional gel shift and DNase I footprinting assays, showed that arlR, sarA, sarX, and icaA are directly regulated by YycF. Our data suggests that YycFG modulates S. epidermidis biofilm formation in an ica-dependent manner.
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Affiliation(s)
- Tao Xu
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Fudan UniversityShanghai, China.,Key Laboratory of Medical Molecular Virology, Huashan Hospital, Shanghai Medical College of Fudan UniversityShanghai, China
| | - Yang Wu
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Fudan UniversityShanghai, China
| | - Zhiwei Lin
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Fudan UniversityShanghai, China
| | - Ralph Bertram
- Klinikum Nürnberg Medical School GmbH, Research Department, Paracelsus Medical UniversityNuremberg, Germany.,Department of Microbial Genetics, Faculty of Science, Interfaculty Institute of Microbiology and Infection Medicine Tübingen, University of TübingenTübingen, Germany
| | - Friedrich Götz
- Department of Microbial Genetics, Faculty of Science, Interfaculty Institute of Microbiology and Infection Medicine Tübingen, University of TübingenTübingen, Germany
| | - Ying Zhang
- Key Laboratory of Medical Molecular Virology, Huashan Hospital, Shanghai Medical College of Fudan UniversityShanghai, China.,Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins UniversityBaltimore, MD, USA
| | - Di Qu
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Fudan UniversityShanghai, China
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Dhanyalakshmi KH, Naika MBN, Sajeevan RS, Mathew OK, Shafi KM, Sowdhamini R, N. Nataraja K. An Approach to Function Annotation for Proteins of Unknown Function (PUFs) in the Transcriptome of Indian Mulberry. PLoS One 2016; 11:e0151323. [PMID: 26982336 PMCID: PMC4794119 DOI: 10.1371/journal.pone.0151323] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 02/27/2016] [Indexed: 01/23/2023] Open
Abstract
The modern sequencing technologies are generating large volumes of information at the transcriptome and genome level. Translation of this information into a biological meaning is far behind the race due to which a significant portion of proteins discovered remain as proteins of unknown function (PUFs). Attempts to uncover the functional significance of PUFs are limited due to lack of easy and high throughput functional annotation tools. Here, we report an approach to assign putative functions to PUFs, identified in the transcriptome of mulberry, a perennial tree commonly cultivated as host of silkworm. We utilized the mulberry PUFs generated from leaf tissues exposed to drought stress at whole plant level. A sequence and structure based computational analysis predicted the probable function of the PUFs. For rapid and easy annotation of PUFs, we developed an automated pipeline by integrating diverse bioinformatics tools, designated as PUFs Annotation Server (PUFAS), which also provides a web service API (Application Programming Interface) for a large-scale analysis up to a genome. The expression analysis of three selected PUFs annotated by the pipeline revealed abiotic stress responsiveness of the genes, and hence their potential role in stress acclimation pathways. The automated pipeline developed here could be extended to assign functions to PUFs from any organism in general. PUFAS web server is available at http://caps.ncbs.res.in/pufas/ and the web service is accessible at http://capservices.ncbs.res.in/help/pufas.
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Affiliation(s)
- K. H. Dhanyalakshmi
- Department of Crop Physiology, University of Agricultural Sciences, GKVK, Bengaluru, 560065, India
| | | | - R. S. Sajeevan
- Department of Crop Physiology, University of Agricultural Sciences, GKVK, Bengaluru, 560065, India
| | - Oommen K. Mathew
- National Centre for Biological Sciences, TIFR, GKVK campus, Bengaluru, 560065, India
| | - K. Mohamed Shafi
- National Centre for Biological Sciences, TIFR, GKVK campus, Bengaluru, 560065, India
| | - Ramanathan Sowdhamini
- National Centre for Biological Sciences, TIFR, GKVK campus, Bengaluru, 560065, India
- * E-mail: ; (KNN); (RS)
| | - Karaba N. Nataraja
- Department of Crop Physiology, University of Agricultural Sciences, GKVK, Bengaluru, 560065, India
- * E-mail: ; (KNN); (RS)
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Hoffmann J, Altenbuchner J. Functional Characterization of the Mannitol Promoter of Pseudomonas fluorescens DSM 50106 and Its Application for a Mannitol-Inducible Expression System for Pseudomonas putida KT2440. PLoS One 2015; 10:e0133248. [PMID: 26207762 PMCID: PMC4514859 DOI: 10.1371/journal.pone.0133248] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 06/24/2015] [Indexed: 01/29/2023] Open
Abstract
A new pBBR1MCS-2-derived vector containing the Pseudomonas fluorescens DSM10506 mannitol promoter PmtlE and mtlR encoding its AraC/XylS type transcriptional activator was constructed and optimized for low basal expression. Mannitol, arabitol, and glucitol-inducible gene expression was demonstrated with Pseudomonas putida and eGFP as reporter gene. The new vector was applied for functional characterization of PmtlE. Identification of the DNA binding site of MtlR was achieved by in vivo eGFP measurement with PmtlE wild type and mutants thereof. Moreover, purified MtlR was applied for detailed in vitro investigations using electrophoretic mobility shift assays and DNaseI footprinting experiments. The obtained data suggest that MtlR binds to PmtlE as a dimer. The proposed DNA binding site of MtlR is AGTGC-N5-AGTAT-N7-AGTGC-N5-AGGAT. The transcription activation mechanism includes two binding sites with different binding affinities, a strong upstream binding site and a weaker downstream binding site. The presence of the weak downstream binding site was shown to be necessary to sustain mannitol-inducibility of PmtlE. Two possible functions of mannitol are discussed; the effector might stabilize binding of the second monomer to the downstream half site or promote transcription activation by inducing a conformational change of the regulator that influences the contact to the RNA polymerase.
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Affiliation(s)
- Jana Hoffmann
- Institut für Industrielle Genetik, Universität Stuttgart, Allmandring 31, 70569, Stuttgart, Germany
| | - Josef Altenbuchner
- Institut für Industrielle Genetik, Universität Stuttgart, Allmandring 31, 70569, Stuttgart, Germany
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The yesN gene encodes a carbohydrate utilization regulatory protein in Lactobacillus plantarum. ANN MICROBIOL 2015. [DOI: 10.1007/s13213-014-0842-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Graf N, Altenbuchner J. Functional characterization and application of a tightly regulated MekR/P mekA expression system in Escherichia coli and Pseudomonas putida. Appl Microbiol Biotechnol 2013; 97:8239-51. [PMID: 23771781 DOI: 10.1007/s00253-013-5030-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 05/28/2013] [Accepted: 05/30/2013] [Indexed: 01/30/2023]
Abstract
A methyl ethyl ketone (MEK)-inducible system based on the broad-host-range plasmid pBBR1MCS2 and on the P mekA promoter region of the MEK degradation operon of Pseudomonas veronii MEK700 was characterized in Escherichia coli JM109 and Pseudomonas putida KT2440. For validation, β-galactosidase (lacZ) was used as a reporter. The novel system, which is positively regulated by MekR, a member of the AraC/XylS family of regulators, was shown to be subject to carbon catabolite repression by glucose, which, however, could not be attributed to the single action of the global regulators Crc and PtsN. An advantage is its extremely tight regulation accompanied with three magnitudes of fold increase of gene expression after treatment with MEK. The transcriptional start site of P mekA was identified by primer extension, thereby revealing a potential stem-loop structure at the 5' end of the mRNA. Since MekR was highly insoluble, its putative binding site was identified through sequence analysis. The operator seems to be composed of a 15-bp tandem repeat (CACCN5CTTCAA) separated by a 6-bp spacer region, which resembles known binding patterns of other members of the AraC/XylS family. Subsequent mutational modifications of the putative operator region confirmed its importance for transcriptional activation. As the -35 promoter element seems to be overlapped by the putative operator, a class II activation mechanism is assumed.
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Affiliation(s)
- Nadja Graf
- Institut für Industrielle Genetik, Universität Stuttgart, Allmandring 31, 70569, Stuttgart, Germany
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A two-component system (XydS/R) controls the expression of genes encoding CBM6-containing proteins in response to straw in Clostridium cellulolyticum. PLoS One 2013; 8:e56063. [PMID: 23418511 PMCID: PMC3572039 DOI: 10.1371/journal.pone.0056063] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 01/03/2013] [Indexed: 12/17/2022] Open
Abstract
The composition of the cellulosomes (multi enzymatic complexes involved in the degradation of plant cell wall polysaccharides) produced by Clostridium cellulolyticum differs according to the growth substrate. In particular, the expression of a cluster of 14 hemicellulase-encoding genes (called xyl-doc) seems to be induced by the presence of straw and not of cellulose. Genes encoding a putative two-component regulation system (XydS/R) were found upstream of xyl-doc. First evidence for the involvement of the response regulator, XydR, part of this two-component system, in the expression of xyl-doc genes was given by the analysis of the cellulosomes produced by a regulator overproducing strain when grown on cellulose. Nano-LC MS/MS analysis allowed the detection of the products of all xyl-doc genes and of the product of the gene at locus Ccel_1656 predicted to bear a carbohydrate binding domain targeting hemicellulose. RT-PCR experiments further demonstrated that the regulation occurs at the transcriptional level and that all xyl-doc genes are transcriptionally linked. mRNA quantification in a regulator knock-out strain and in its complemented derivative confirmed the involvement of the regulator in the expression of xyl-doc genes and of the gene at locus Ccel_1656 in response to straw. Electrophoretic mobility shift assays using the purified regulator further demonstrated that the regulator binds to DNA regions located upstream of the first gene of the xyl-doc gene cluster and upstream of the gene at locus Ccel_1656.
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